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Saint Helier, Jersey climate
Cfb Oceanic / temperate
Saint Helier has a mildly seasonal cool-temperate climate (Oceanic / temperate, Köppen Cfb). The hottest month is August with an average daily high near 21°C, while the coldest is February averaging around 4°C at night. Around 895 mm of precipitation falls each year, peaking in December (122 mm) and easing off in July (47 mm).
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresHours of sunshine per day
Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)Saint Helier climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 9 | 9 | 11 | 13 | 16 | 19 | 21 | 21 | 19 | 15 | 12 | 10 |
| Avg temp (°C) | 7 | 7 | 8 | 10 | 13 | 15 | 17 | 18 | 16 | 13 | 10 | 8 |
| Avg low (°C) | 5 | 4 | 6 | 7 | 10 | 12 | 14 | 14 | 13 | 11 | 8 | 5 |
| Precipitation (mm) | 93 | 76 | 62 | 56 | 52 | 50 | 47 | 60 | 61 | 103 | 113 | 122 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 9 | 9 | 11 | 13 | 16 | 19 |
| Avg temp (°C) | 7 | 7 | 8 | 10 | 13 | 15 |
| Avg low (°C) | 5 | 4 | 6 | 7 | 10 | 12 |
| Precipitation (mm) | 93 | 76 | 62 | 56 | 52 | 50 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 21 | 21 | 19 | 15 | 12 | 10 |
| Avg temp (°C) | 17 | 18 | 16 | 13 | 10 | 8 |
| Avg low (°C) | 14 | 14 | 13 | 11 | 8 | 5 |
| Precipitation (mm) | 47 | 60 | 61 | 103 | 113 | 122 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 20 | 17 | 15 | 14 | 12 | 11 | 11 | 12 | 12 | 18 | 20 | 20 |
| Days with high ≥ 32°C (days) | — | — | — | — | — | 0.0 | 0.1 | 0.1 | — | — | — | — |
| Days with low ≤ 0°C (days) | 3 | 3 | 0.8 | 0.0 | — | — | — | — | — | — | 0.4 | 2 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 20 | 17 | 15 | 14 | 12 | 11 |
| Days with high ≥ 32°C (days) | — | — | — | — | — | 0.0 |
| Days with low ≤ 0°C (days) | 3 | 3 | 0.8 | 0.0 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 11 | 12 | 12 | 18 | 20 | 20 |
| Days with high ≥ 32°C (days) | 0.1 | 0.1 | — | — | — | — |
| Days with low ≤ 0°C (days) | — | — | — | — | 0.4 | 2 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 83 | 81 | 77 | 69 | 68 | 66 | 64 | 67 | 67 | 77 | 82 | 83 |
| Relative humidity (%) | 84 | 84 | 85 | 84 | 85 | 86 | 86 | 84 | 82 | 82 | 83 | 84 |
| Wind speed (mph) | 15.6 | 14.4 | 12.8 | 11.3 | 10.5 | 9.7 | 9.6 | 10.0 | 11.7 | 13.8 | 15.1 | 15.8 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 83 | 81 | 77 | 69 | 68 | 66 |
| Relative humidity (%) | 84 | 84 | 85 | 84 | 85 | 86 |
| Wind speed (mph) | 15.6 | 14.4 | 12.8 | 11.3 | 10.5 | 9.7 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 64 | 67 | 67 | 77 | 82 | 83 |
| Relative humidity (%) | 86 | 84 | 82 | 82 | 83 | 84 |
| Wind speed (mph) | 9.6 | 10.0 | 11.7 | 13.8 | 15.1 | 15.8 |
Methodology & sources
Temperature & precipitation — 1991–2020 normals computed from 30 years of daily observations at Jersey: Airport, a weather station, about 8 km from the city centre. The underlying daily records come from NOAA's global station network.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.