Annual report

UK Wave and Sea Temperature Almanac 2023

A comparison of hourly-normalized observations from UK coastal and marine wave stations. The report uses only sufficiently complete station-years for each comparison and publishes the station evidence alongside every chart.

Data snapshot updated 21 August 2026. Published 21 August 2026.

Executive summary

In Southwest England, the regional monthly mean was highest in December at 1.63 m and lowest in June at 0.50 m. Other regions follow their own seasonal pattern.
The largest accepted significant wave height was 11.7 m at Bideford Bay in April. A sustained sequence around the peak supports it as a storm event rather than an isolated spike.
The highest monthly mean sea temperature was 19.4 °C at Rustington; the lowest was 5.7 °C at Chapel Point.
The Copernicus gridded sea-surface temperature anomaly for UK and nearby waters was +0.60 °C against the 1991–2020 monthly climatology.
Automated checks examined 1,500,906 values at wave-eligible stations and excluded 4,443, or 0.30%.

Station-years represented: 41
Wave-comparison stations: 22
Temperature stations: 21
Minimum day coverage: 95%

Regional seasonal wave patterns

Combining all UK stations would mix different wave climates and overstate regions with more buoys. Each panel therefore shows one region. A monthly value first summarizes one accepted value per station per UTC hour, then gives every eligible station in that region equal weight. The shaded band averages the station-level 10th and 90th percentiles using the same equal weighting. Every panel uses the same zero-based vertical scale, so line heights can be compared directly between regions.

Region links open the current wave-buoy map. If a historical region no longer exists, the map shows all regions.

Regional seasonal patterns are shown separately. The shaded area is the equal-weighted average of each station's monthly 10th–90th percentile range. For example, Southwest England ranged from 0.50 m in June to 1.63 m in December. All panels use the same zero-based vertical scale, so their absolute heights can be compared directly. Download chart as SVG.

View chart values for average significant wave height by month and region

Regional monthly wave-height chart values
Region	Month	Mean significant wave height	10th–90th percentile range	Stations
Southwest England	January	1.50 m	0.55–2.82 m	6
Southwest England	February	0.97 m	0.48–1.43 m	6
Southwest England	March	1.45 m	0.63–2.40 m	6
Southwest England	April	0.97 m	0.38–1.70 m	6
Southwest England	May	0.63 m	0.27–1.20 m	6
Southwest England	June	0.50 m	0.23–1.00 m	6
Southwest England	July	0.88 m	0.40–1.45 m	6
Southwest England	August	0.78 m	0.32–1.48 m	6
Southwest England	September	0.92 m	0.30–1.77 m	6
Southwest England	October	1.08 m	0.48–1.88 m	6
Southwest England	November	1.48 m	0.45–2.65 m	6
Southwest England	December	1.63 m	0.60–2.72 m	6
South Coast England	January	0.94 m	0.26–1.92 m	5
South Coast England	February	0.50 m	0.24–0.82 m	5
South Coast England	March	0.96 m	0.40–1.64 m	5
South Coast England	April	0.64 m	0.28–1.14 m	5
South Coast England	May	0.40 m	0.16–0.80 m	5
South Coast England	June	0.40 m	0.18–0.70 m	5
South Coast England	July	0.70 m	0.32–1.24 m	5
South Coast England	August	0.56 m	0.24–1.00 m	5
South Coast England	September	0.60 m	0.20–1.30 m	5
South Coast England	October	0.82 m	0.36–1.50 m	5
South Coast England	November	0.98 m	0.26–1.78 m	5
South Coast England	December	1.12 m	0.42–2.02 m	5
Southeast England	January	1.06 m	0.28–2.20 m	5
Southeast England	February	0.54 m	0.22–1.08 m	5
Southeast England	March	0.96 m	0.38–1.72 m	5
Southeast England	April	0.68 m	0.26–1.24 m	5
Southeast England	May	0.44 m	0.24–0.70 m	5
Southeast England	June	0.44 m	0.20–0.74 m	5
Southeast England	July	0.84 m	0.28–1.54 m	5
Southeast England	August	0.62 m	0.22–1.08 m	5
Southeast England	September	0.64 m	0.18–1.48 m	5
Southeast England	October	0.90 m	0.40–1.66 m	5
Southeast England	November	1.26 m	0.44–2.22 m	5
Southeast England	December	1.30 m	0.42–2.20 m	5
Lincolnshire and East Anglia	January	0.85 m	0.30–1.45 m	2
Lincolnshire and East Anglia	February	0.65 m	0.25–1.15 m	2
Lincolnshire and East Anglia	March	0.95 m	0.50–1.40 m	2
Lincolnshire and East Anglia	April	0.85 m	0.40–1.45 m	2
Lincolnshire and East Anglia	May	0.75 m	0.30–1.25 m	2
Lincolnshire and East Anglia	June	0.60 m	0.20–1.00 m	2
Lincolnshire and East Anglia	July	0.65 m	0.35–1.05 m	2
Lincolnshire and East Anglia	August	0.60 m	0.30–1.10 m	2
Lincolnshire and East Anglia	September	0.65 m	0.25–1.30 m	2
Lincolnshire and East Anglia	October	0.95 m	0.50–1.65 m	2
Lincolnshire and East Anglia	November	0.95 m	0.50–1.60 m	2
Lincolnshire and East Anglia	December	1.00 m	0.55–1.70 m	2
Northeast England	January	0.97 m	0.40–1.60 m	3
Northeast England	February	0.90 m	0.37–1.73 m	3
Northeast England	March	1.27 m	0.57–1.97 m	3
Northeast England	April	1.03 m	0.47–1.97 m	3
Northeast England	May	0.73 m	0.30–1.30 m	3
Northeast England	June	0.57 m	0.20–0.97 m	3
Northeast England	July	0.70 m	0.30–1.17 m	3
Northeast England	August	0.77 m	0.20–1.57 m	3
Northeast England	September	0.60 m	0.23–1.17 m	3
Northeast England	October	1.53 m	0.40–3.00 m	3
Northeast England	November	1.23 m	0.57–2.10 m	3
Northeast England	December	1.27 m	0.50–2.27 m	3
Northwest England	January	1.30 m	0.50–2.30 m	1
Northwest England	February	0.90 m	0.30–1.60 m	1
Northwest England	March	0.80 m	0.20–1.60 m	1
Northwest England	April	0.60 m	0.20–1.20 m	1
Northwest England	May	0.50 m	0.20–0.90 m	1
Northwest England	June	0.40 m	0.20–1.00 m	1
Northwest England	July	1.00 m	0.40–1.70 m	1
Northwest England	August	0.80 m	0.40–1.30 m	1
Northwest England	September	0.80 m	0.10–1.80 m	1
Northwest England	October	0.80 m	0.30–1.80 m	1
Northwest England	November	1.10 m	0.30–2.00 m	1
Northwest England	December	1.50 m	0.40–2.70 m	1

Regional comparison

Each range bar shows the regional 10th–90th percentile bounds, with the annual mean marked in gold. Regions with one station describe that station alone. Offshore and nearshore regions should not be compared as equivalent measures of surf conditions.

Annual means and percentile bounds are equal-weighted across eligible stations in each region. The range is the average of the station-level annual P10 and P90 values, and the gold marker is the annual mean. Download chart as SVG.

View chart values for average significant wave height by region

Regional wave-height chart values
Region	Annual mean	10th–90th percentile range	Stations
Southwest England	1.07 m	0.33–2.07 m	6
South Coast England	0.72 m	0.24–1.44 m	5
Southeast England	0.80 m	0.25–1.68 m	5
Lincolnshire and East Anglia	0.79 m	0.32–1.36 m	2
Northeast England	0.98 m	0.33–1.81 m	3
Northwest England	0.88 m	0.21–1.83 m	1

Largest accepted height by region

Largest accepted significant wave height by region
Region	Station	Largest height
Southwest England	Bideford Bay	11.7 m
South Coast England	Chesil	6.3 m
Southeast England	Seaford	5.1 m
Lincolnshire and East Anglia	Lowestoft	4.6 m
Northeast England	Newbiggin	8.3 m
Northwest England	Cleveleys	4.6 m

Sea temperatures

Monthly means are used for the range comparison. This reduces the influence of a single bad sensor reading while preserving the annual cycle. The chart shows the 15 eligible stations with the highest annual mean; all eligible stations remain in the supporting table.

Each teal bar spans the lowest to highest monthly mean, and the gold marker shows the annual mean. This is not a chart of raw recorded extrema. Download chart as SVG.

View chart values for monthly sea temperature range at the 15 warmest stations

Sea-temperature chart values
Station	Lowest monthly mean	Annual mean	Highest monthly mean
Perranporth	9.9 °C	13.6 °C	17.6 °C
Sandown Bay	8.1 °C	13.6 °C	19.2 °C
Rustington	7.8 °C	13.6 °C	19.4 °C
Bracklesham Bay	7.6 °C	13.6 °C	19.4 °C
Bideford Bay	8.9 °C	13.5 °C	18.3 °C
Seaford	7.9 °C	13.5 °C	19.4 °C
Looe Bay	9.5 °C	13.4 °C	17.6 °C
Weymouth	8.6 °C	13.4 °C	18.6 °C
Boscombe	8.0 °C	13.4 °C	18.9 °C
Folkestone	7.9 °C	13.4 °C	19.1 °C
Pevensey Bay	7.8 °C	13.4 °C	19.2 °C
Porthleven	10.0 °C	13.3 °C	17.2 °C
Start Bay	9.2 °C	13.3 °C	17.8 °C
West Bay	8.6 °C	13.3 °C	18.0 °C
Chesil	8.7 °C	13.3 °C	18.3 °C

Copernicus sea-temperature anomaly

Why does a 1 °C sea-temperature anomaly matter?

A degree can sound small because air temperature changes quickly. The ocean is different: water needs a great deal of energy to warm, and it releases that heat slowly. The IPCC estimates that ocean warming accounted for 91% of the heating of the climate system between 2006 and 2018.

One cubic metre of seawater

about 1.1 kWh per 1 °C

One square kilometre, 1 m deep

about 1.1 GWh per 1 °C

That second amount is roughly the energy used by a 1 kW household appliance running continuously for 127 years. Watts describe the rate of energy use; kilowatt-hours describe the total energy. The calculation uses seawater's approximate specific heat capacity of 4,000 joules per kilogram per degree Celsius.

Stored ocean heat expands seawater and raises sea level. A warmer starting point also makes damaging marine heatwaves more likely and can stress ecosystems and fisheries. These effects become more widespread with each additional increment of warming.

This is an illustration of scale, not an estimate of the heat in the chart area: a sea-surface anomaly does not mean the whole upper metre warmed uniformly. The report compares one year in UK and nearby waters with its 1991–2020 monthly baseline. It is not the global long-term warming threshold, and individual years also include natural variability.

This separate gridded view shows how warm or cool the wider sea surface was relative to the 1991–2020 monthly climatology. Positive values mean warmer than the baseline for that calendar month. The analysis covers valid ocean cells from 48–62°N and 12°W–4°E and does not alter the observed buoy findings above.

Annual SST anomaly: +0.60 °C
Largest warm anomaly: Jun +1.7 °C
Largest cool anomaly: Dec +0.21 °C
Gridded minus buoy median: -0.27 °C

Monthly anomalies compare 2023 with the matching 1991–2020 calendar-month mean. The annual anomaly is the mean of the 12 monthly anomalies, not a comparison with one annual threshold. Download chart as SVG.

View chart values for copernicus monthly sea-temperature anomaly

Copernicus monthly sea-temperature anomaly chart values
Month	Anomaly	2023 gridded mean	1991–2020 mean	Valid days
Jan	+0.40 °C	9.33 °C	8.93 °C	31
Feb	+0.46 °C	8.79 °C	8.34 °C	28
Mar	+0.41 °C	8.58 °C	8.17 °C	31
Apr	+0.51 °C	9.27 °C	8.76 °C	30
May	+0.56 °C	10.82 °C	10.26 °C	31
Jun	+1.73 °C	14.13 °C	12.40 °C	30
Jul	+0.76 °C	15.05 °C	14.29 °C	31
Aug	+0.31 °C	15.47 °C	15.16 °C	31
Sept	+1.10 °C	15.45 °C	14.35 °C	30
Oct	+0.57 °C	13.41 °C	12.84 °C	31
Nov	+0.23 °C	11.46 °C	11.22 °C	30
Dec	+0.21 °C	10.11 °C	9.89 °C	31

The gridded field had 100.0% daily coverage for this calculation. At 21 eligible buoy sites, 252 matched station-months had a mean absolute difference of 0.29 °C. The nearest valid ocean cells were no more than 2.7 km from a buoy.

Source: Copernicus Marine C3S reprocessed SST dataset C3S-GLO-SST-L4-REP-OBS-SST_202506, DOI 10.48670/moi-00169.

Coverage and quality control

A station needs observations on at least 95% of days and accepted measurements in at least 90% of annual hours to enter that metric's comparison. Stations below the threshold are still listed for transparency.

Day coverage counts any UTC day with an observation. Metric-hour coverage is tested separately before wave-height or temperature comparisons are made. Download chart as SVG.

View chart values for observation day coverage by station

Station coverage chart values
Day coverage band	Stations
Under 50%	2
50-79%	4
80-94%	13
95-99%	5
100%	17

Largest station-month peaks

These are the largest accepted monthly maxima among eligible stations. Repeated entries for a station reflect separate stormy months, not duplicate observations.

Largest accepted station-month significant wave heights
Month	Station	Region	Maximum
April	Bideford Bay	Southwest England	11.7 m
October	Newbiggin	Northeast England	8.3 m
March	Porthleven	Southwest England	7.9 m
October	Scarborough	Northeast England	7.5 m
November	Porthleven	Southwest England	7.2 m
April	Perranporth	Southwest England	6.9 m
November	Perranporth	Southwest England	6.7 m
November	Chesil	South Coast England	6.3 m

Supporting station table

This table contains every station-year considered. A dash means the metric was unavailable. “Included” indicates that the station met the day and metric-hour thresholds for that comparison.

All UK stations considered in the 2023 almanac
Station	Region	Day coverage	Wave status	Wave hours	Mean Hs	Median Hs	Annual Hs P10–P90	Maximum Hs	Temperature status	Annual temperature	Monthly mean range	Excluded values
St Mary's SoundChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	91.0%331 days	Below threshold	7,90290.2%	1.31 m	1.13 m	0.52–2.41 m	5.3 m	Below threshold	13.3 °C	10.2 °C to 15.9 °C	1700.30%
SevenstonesLegacy SurfHog archive	Southwest England	79.0%289 days	Below threshold	5,01557.2%	1.62 m	1.40 m	0.61–2.99 m	8.2 m	Below threshold	14.2 °C	10.2 °C to 16.9 °C	550.30%
PerranporthChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	99.0%360 days	Included	8,58198.0%	1.65 m	1.46 m	0.52–3.05 m	6.9 m	Included	13.6 °C	9.9 °C to 17.6 °C	1980.30%
Port IsaacChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	95.0%347 days	Included	8,26194.3%	0.46 m	0.37 m	0.12–0.91 m	2.3 m	Below threshold	Not available	Not available	3591.10%
PenzanceChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	85.0%311 days	Below threshold	7,44785.0%	0.70 m	0.55 m	0.21–1.40 m	4.1 m	Below threshold	13.8 °C	9.7 °C to 17.3 °C	2700.50%
PorthlevenChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	100.0%365 days	Included	8,75299.9%	1.34 m	1.07 m	0.43–2.77 m	7.9 m	Included	13.3 °C	10.0 °C to 17.2 °C	2750.40%
Looe BayChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	100.0%365 days	Included	8,760100.0%	0.94 m	0.76 m	0.30–1.83 m	5.0 m	Included	13.4 °C	9.5 °C to 17.6 °C	2410.30%
MineheadChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	58.0%213 days	Below threshold	5,06557.8%	0.58 m	0.49 m	0.18–1.07 m	2.3 m	Below threshold	13.4 °C	8.0 °C to 18.5 °C	1100.30%
Bideford BayChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	100.0%365 days	Included	8,74999.9%	1.28 m	1.04 m	0.37–2.50 m	11.7 m	Included	13.5 °C	8.9 °C to 18.3 °C	2560.40%
Weston BayChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	76.0%279 days	Below threshold	6,65576.0%	0.43 m	0.34 m	0.09–0.91 m	2.3 m	Below threshold	12.3 °C	7.1 °C to 18.7 °C	500.10%
Start BayChannel Coastal Observatory, Legacy SurfHog archive	Southwest England	100.0%365 days	Included	8,71999.5%	0.73 m	0.58 m	0.24–1.37 m	3.5 m	Included	13.3 °C	9.2 °C to 17.8 °C	2780.40%
DawlishChannel Coastal Observatory	Southwest England	91.0%333 days	Below threshold	7,87489.9%	0.55 m	0.43 m	0.18–1.07 m	3.3 m	Below threshold	13.8 °C	8.9 °C to 18.3 °C	2880.50%
West BayChannel Coastal Observatory, Legacy SurfHog archive	South Coast England	100.0%365 days	Included	8,75599.9%	0.94 m	0.70 m	0.30–1.92 m	6.3 m	Included	13.3 °C	8.6 °C to 18.0 °C	3520.50%
WeymouthChannel Coastal Observatory, Legacy SurfHog archive	South Coast England	100.0%365 days	Included	8,756100.0%	0.49 m	0.40 m	0.18–0.91 m	2.6 m	Included	13.4 °C	8.6 °C to 18.6 °C	2010.30%
BoscombeChannel Coastal Observatory, Legacy SurfHog archive	South Coast England	100.0%365 days	Included	8,73799.7%	0.58 m	0.46 m	0.21–1.13 m	3.8 m	Included	13.4 °C	8.0 °C to 18.9 °C	2500.40%
ChesilChannel Coastal Observatory	South Coast England	100.0%365 days	Included	8,75599.9%	1.07 m	0.82 m	0.34–2.23 m	6.3 m	Included	13.3 °C	8.7 °C to 18.3 °C	2000.30%
Sandown BayChannel Coastal Observatory	South Coast England	100.0%365 days	Included	8,67599.0%	0.52 m	0.43 m	0.18–1.04 m	3.9 m	Included	13.6 °C	8.1 °C to 19.2 °C	1520.20%
RustingtonChannel Coastal Observatory, Legacy SurfHog archive	Southeast England	96.0%350 days	Included	8,34595.3%	0.88 m	0.73 m	0.30–1.80 m	4.8 m	Included	13.6 °C	7.8 °C to 19.4 °C	1720.30%
SeafordChannel Coastal Observatory, Legacy SurfHog archive	Southeast England	100.0%364 days	Included	8,65698.8%	0.88 m	0.61 m	0.21–1.98 m	5.1 m	Included	13.5 °C	7.9 °C to 19.4 °C	1720.20%
FolkestoneChannel Coastal Observatory, Legacy SurfHog archive	Southeast England	99.0%362 days	Included	8,59498.1%	0.58 m	0.49 m	0.21–1.13 m	3.8 m	Included	13.4 °C	7.9 °C to 19.1 °C	1170.20%
Pevensey BayChannel Coastal Observatory, Legacy SurfHog archive	Southeast England	100.0%365 days	Included	8,65998.8%	0.85 m	0.67 m	0.27–1.71 m	4.4 m	Included	13.4 °C	7.8 °C to 19.2 °C	1200.20%
Bracklesham BayChannel Coastal Observatory	Southeast England	100.0%365 days	Included	8,73299.7%	0.82 m	0.64 m	0.24–1.77 m	3.8 m	Included	13.6 °C	7.6 °C to 19.4 °C	2370.30%
Chapel PointChannel Coastal Observatory	Lincolnshire and East Anglia	98.0%359 days	Included	8,58998.0%	0.76 m	0.70 m	0.30–1.28 m	3.3 m	Included	11.9 °C	5.7 °C to 18.2 °C	1750.30%
HappisburghChannel Coastal Observatory	Lincolnshire and East Anglia	81.0%295 days	Below threshold	7,05280.5%	0.70 m	0.58 m	0.27–1.28 m	3.6 m	Below threshold	10.4 °C	5.5 °C to 18.2 °C	1460.30%
LowestoftChannel Coastal Observatory	Lincolnshire and East Anglia	100.0%365 days	Included	8,73999.8%	0.82 m	0.73 m	0.34–1.43 m	4.6 m	Included	12.1 °C	5.9 °C to 18.7 °C	830.10%
NewbigginChannel Coastal Observatory, Legacy SurfHog archive	Northeast England	100.0%365 days	Included	8,74899.9%	1.01 m	0.79 m	0.30–1.89 m	8.3 m	Included	10.3 °C	6.9 °C to 14.1 °C	1850.30%
ScarboroughChannel Coastal Observatory, Legacy SurfHog archive	Northeast England	100.0%365 days	Included	8,72599.6%	1.10 m	0.88 m	0.37–2.04 m	7.5 m	Included	10.7 °C	7.0 °C to 14.6 °C	1730.20%
WhitbyChannel Coastal Observatory, Legacy SurfHog archive	Northeast England	94.0%342 days	Below threshold	8,18593.4%	1.04 m	0.85 m	0.30–2.04 m	7.3 m	Below threshold	10.7 °C	6.5 °C to 14.4 °C	1580.20%
HornseaChannel Coastal Observatory	Northeast England	100.0%365 days	Included	8,72899.6%	0.82 m	0.70 m	0.30–1.49 m	5.2 m	Included	11.0 °C	6.9 °C to 15.5 °C	1710.20%
CleveleysChannel Coastal Observatory, Legacy SurfHog archive	Northwest England	100.0%365 days	Included	8,75299.9%	0.88 m	0.67 m	0.21–1.83 m	4.6 m	Included	12.2 °C	6.8 °C to 17.9 °C	760.10%
Morecambe BayChannel Coastal Observatory, Legacy SurfHog archive	Northwest England	84.0%307 days	Below threshold	7,33883.8%	0.76 m	0.61 m	0.18–1.58 m	4.0 m	Below threshold	12.1 °C	6.7 °C to 18.0 °C	910.20%
Rhyl FlatsLegacy SurfHog archive	Wales	0.0%0 days	Below threshold	00.0%	Not available	Not available	Not available	Not available	Below threshold	Not available	Not available	00.00%
K7Legacy SurfHog archive	West Scotland	88.0%320 days	Below threshold	1,05212.0%	0.00 m	0.00 m	0.00–0.00 m	0.0 m	Below threshold	10.7 °C	9.4 °C to 12.8 °C	1,72012.90%
SandettieLegacy SurfHog archive	English Channel	88.0%320 days	Below threshold	7,60986.9%	0.67 m	0.49 m	0.21–1.40 m	4.0 m	Below threshold	14.0 °C	8.6 °C to 18.7 °C	430.10%
Ch. LightshipLegacy SurfHog archive	English Channel	88.0%320 days	Below threshold	7748.8%	0.00 m	0.00 m	0.00–0.00 m	0.0 m	Below threshold	14.2 °C	10.3 °C to 17.1 °C	2,2639.50%
F3Legacy SurfHog archive	Southern North Sea	68.0%247 days	Below threshold	5,91367.5%	0.67 m	0.49 m	0.21–1.40 m	3.6 m	Below threshold	15.3 °C	10.7 °C to 18.8 °C	10.00%
GreenwichLegacy SurfHog archive	Southern North Sea	88.0%320 days	Below threshold	7,61887.0%	0.91 m	0.61 m	0.30–2.01 m	5.8 m	Below threshold	13.9 °C	9.2 °C to 18.1 °C	300.10%
Anasuria AWSLegacy SurfHog archive	Central and Northern North Sea	88.0%320 days	Below threshold	1,26814.5%	0.00 m	0.00 m	0.00–0.00 m	0.0 m	Below threshold	Not available	Not available	1,2477.10%
Beryl A AWSLegacy SurfHog archive	Central and Northern North Sea	88.0%320 days	Below threshold	7,15481.7%	2.19 m	1.89 m	0.79–3.99 m	10.4 m	Below threshold	Not available	Not available	420.10%
Cormorant AWSLegacy SurfHog archive	Central and Northern North Sea	88.0%320 days	Below threshold	7,50485.7%	2.44 m	2.10 m	1.01–4.30 m	11.5 m	Below threshold	Not available	Not available	330.10%
Eider AWSLegacy SurfHog archive	Central and Northern North Sea	0.0%0 days	Below threshold	00.0%	Not available	Not available	Not available	Not available	Below threshold	Not available	Not available	00.00%

Method and limitations

The analysis uses the newest stored 2023 annual snapshot for each station in the defined UK coastal and marine regions. Measurements are normalized to one accepted value per station per UTC hour without filling gaps. Regional and monthly comparisons weight eligible stations equally. Temperatures in the findings are monthly means, while wave peaks are accepted individual significant wave heights.

Offshore and nearshore stations are not directly comparable as measures of surf conditions. Coverage does not guarantee sensor accuracy, and automated checks can miss sustained faults. Source availability and later corrections can change a rebuilt annual snapshot. See the full data and methodology notes for source terms, hard limits, unit conversions and the observed-versus-calculated distinction.

Copernicus anomalies are calculated independently from the buoy summaries. Daily 0.05° analysed SST is averaged across valid ocean grid cells using cosine-latitude area weights, then summarized to monthly means. Each monthly anomaly is measured against the matching 1991–2020 monthly climatology, and the annual anomaly is the mean of those 12 differences. The rectangular 48–62°N, 12°W–4°E window is a reproducible analysis area, not a legal or forecast-region boundary. Buoy comparisons use the nearest valid ocean grid cell within 20 km, so coastal position and grid-cell footprint can produce genuine differences.

Cite and share this report

Suggested citation: SurfHog (2026), “UK Wave and Sea Temperature Almanac 2023”, data updated 21 August 2026, https://www.surfhog.co.uk/reports/uk-wave-sea-temperature-almanac-2023

Cite the original observation providers as well as SurfHog when using a specific station finding. Provider and reuse details are listed in the data and methodology page.