Climate averages 1991–2020
Saint Helier weather
by month.
See how the year changes. August has the highest average daily maximum; July has the lowest average monthly rainfall.
Long-term climate patterns, not a forecast for a particular trip.
Across the year Saint Helier averages a daytime high of 13.3°C and a nighttime low of 10.9°C, with about 1,000 mm of rain on roughly 149 days. August is the warmest month (average high 18.5°C) and February the coolest (8.7°C). December is the wettest month with 138 mm; July is the driest with 48 mm.
The annual picture
A year in Saint Helier
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Saint Helier climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 9.1°C6.8°C | 6.8°C | 110 | 15.8 | 8.79 h |
| February | 8.7°C6.3°C | 6.3°C | 82 | 13.0 | 10.110 h |
| March | 9.7°C7.3°C | 7.3°C | 69 | 12.4 | 11.912 h |
| April | 11.3°C8.6°C | 8.6°C | 57 | 10.5 | 13.714 h |
| May | 13.7°C11.0°C | 11.0°C | 53 | 9.4 | 15.315 h |
| June | 16.1°C13.4°C | 13.4°C | 50 | 8.7 | 16.216 h |
| July | 17.9°C15.4°C | 15.4°C | 48 | 9.1 | 15.816 h |
| August | 18.5°C16.1°C | 16.1°C | 63 | 9.8 | 14.414 h |
| September | 17.5°C15.1°C | 15.1°C | 77 | 11.0 | 12.713 h |
| October | 15.2°C12.9°C | 12.9°C | 122 | 15.5 | 10.811 h |
| November | 12.2°C10.0°C | 10.0°C | 132 | 17.6 | 9.29 h |
| December | 10.0°C7.7°C | 7.7°C | 138 | 16.7 | 8.38 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
Nearby cities
- RennesFrance · 124 kmHigh 15.7°C · Low 8.3°C · 688 mm rain a year
- CaenFrance · 127 kmHigh 15.1°C · Low 8.4°C · 713 mm rain a year
- Le HavreFrance · 164 kmHigh 14.3°C · Low 9.2°C · 950 mm rain a year
- PooleUnited Kingdom · 170 kmHigh 13.7°C · Low 9.0°C · 736 mm rain a year
- BournemouthUnited Kingdom · 171 kmHigh 13.7°C · Low 8.9°C · 736 mm rain a year
- PortsmouthUnited Kingdom · 193 kmHigh 14.0°C · Low 8.3°C · 812 mm rain a year
- Brest, FranceFrance · 196 kmHigh 14.0°C · Low 10.3°C · 858 mm rain a year
- PlymouthUnited Kingdom · 197 kmHigh 13.6°C · Low 8.8°C · 947 mm rain a year
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsWhat do the high and low temperatures mean?
We average the daily maximum and daily minimum for each calendar month over 1991–2020. They are not record extremes, a forecast range or temperatures at a fixed time of day.
How is a rain day counted?
A local calendar day (standard time, UTC±0, no daylight saving) with at least 1 mm of total precipitation counts as one rain day. We count these for each year and month, then average across 30 years. The average does not predict which days will be wet.
Where do the numbers come from?
ERA5-Land (temperature) and ERA5 (precipitation) reanalysis from the Copernicus Climate Change Service, read from the Open-Meteo open-data archive. Temperature comes from the 0.1° model cell at 49.20°, -2.20° (7 km from the city centre). Rain comes from the 0.25° cell at 49.25°, -2.00°. These are model estimates, not weather-station readings; coast, hills and city streets can differ.
Does this page show sunshine, humidity or sea temperature?
No. The data used here contain air temperature and precipitation only. Daylight hours are calculated from the city's latitude (sunrise to sunset), not measured sunshine.