Sunbury-on-Thames, United Kingdom Climate
The warmest month is July, with an average high of 23°C; the coldest is February, with an average low of 1°C. A normal year brings 747 mm of precipitation.
Temperature through the year
The normal daily high and low. The line marks today.
- Normal low
- Normal high
- Reanalysis extreme high
- Reanalysis extreme low
Normals for Sep 25
- Normal high
- 19°C
- Normal low
- 9°C
- Reanalysis high
- 22°Cin 1998
- Reanalysis low
- 4°Cin 2010
- Chance of a wet day
- 42%
- Daylight
- 12 h 01 min
Month by month
Averages for 1991-2020. Wet days have at least 1 mm of precipitation in the reanalysis. Each month links to its own page.
| Month | Avg high | Avg low | Warmest | Coldest | Precipitation | Wet days |
|---|---|---|---|---|---|---|
| January | 7°C | 1°C | 13°C (2016) | -8°C (2009) | 68 mm | 12.4 |
| February | 7°C | 1°C | 17°C (2019) | -9°C (2012) | 54 mm | 11.3 |
| March | 10°C | 2°C | 19°C (2012) | -5°C (2018) | 50 mm | 12.4 |
| April | 13°C | 4°C | 25°C (2018) | -4°C (1996) | 51 mm | 12.0 |
| May | 17°C | 7°C | 27°C (2005) | -2°C (1996) | 56 mm | 12.4 |
| June | 20°C | 10°C | 31°C (2017) | 1°C (1991) | 60 mm | 12.0 |
| July | 23°C | 12°C | 35°C (2019) | 6°C (1993) | 56 mm | 12.4 |
| August | 23°C | 12°C | 35°C (2003) | 5°C (2014) | 65 mm | 12.4 |
| September | 20°C | 10°C | 30°C (2016) | 3°C (2003) | 57 mm | 12.0 |
| October | 15°C | 7°C | 28°C (2011) | -4°C (2008) | 78 mm | 12.4 |
| November | 10°C | 4°C | 18°C (1996) | -5°C (2010) | 78 mm | 15.0 |
| December | 7°C | 2°C | 14°C (2015) | -7°C (1995) | 74 mm | 12.4 |
| Year | 14°C | 6°C | 747 mm | 149 |
Precipitation
Rain and melted snow together. The chance of a wet day is the share of days with at least 1 mm of precipitation in the reanalysis.
747 mm in a normal year, most in October.
Chance of a wet day
- Chance of a wet day
Humidity and comfort
NASA POWER reanalysis, 1991-2020, for the grid cell around Sunbury-on-Thames.
Days with a mean dew point of 18°C or more are rare here in every month.
| Month | Dew point | Humidity | Dry | Comfortable | Humid | Muggy | Oppressive | Miserable |
|---|---|---|---|---|---|---|---|---|
| January | 3°C | 94% | 100% | 0% | 0% | 0% | 0% | 0% |
| February | 3°C | 92% | 100% | 0% | 0% | 0% | 0% | 0% |
| March | 4°C | 88% | 100% | 0% | 0% | 0% | 0% | 0% |
| April | 6°C | 83% | 100% | 0% | 0% | 0% | 0% | 0% |
| May | 8°C | 80% | 94% | 6% | 0% | 0% | 0% | 0% |
| June | 11°C | 78% | 79% | 18% | 3% | 0% | 0% | 0% |
| July | 12°C | 74% | 57% | 37% | 7% | 0% | 0% | 0% |
| August | 12°C | 75% | 58% | 34% | 9% | 0% | 0% | 0% |
| September | 11°C | 80% | 77% | 22% | 2% | 0% | 0% | 0% |
| October | 9°C | 87% | 91% | 9% | 0% | 0% | 0% | 0% |
| November | 6°C | 93% | 100% | 0% | 0% | 0% | 0% | 0% |
| December | 4°C | 95% | 100% | 0% | 0% | 0% | 0% | 0% |
Comfort is judged by the day's mean dew point: dry below 13°C, comfortable to 16°C, humid to 18°C, muggy to 21°C, oppressive to 24°C, miserable above.
Clouds
Average share of the sky covered, from satellite (CERES and GEWEX SRB) by way of NASA POWER, 1991-2020.
The clearest month is September, with the sky 69 percent covered on average; the cloudiest is November, at 74 percent.
Wind
The mean wind speed over the whole day, from the MERRA-2 reanalysis by way of NASA POWER. Gusts run well above it.
The windiest month is January, averaging 20.9 km/h at 10 meters (33 feet) above the ground.
Daylight and sunshine
The longest day is Jun 18, with 16 h 38 min of daylight; the shortest is Dec 19, with 7 h 50 min.
- Day length
Solar energy
Average daily sunshine reaching the ground on a flat surface, in kilowatt-hours per square meter, clouds included.
Month pages
The weather in Sunbury-on-Thames in each month, day by day.
What this means
A normal is the average of the thirty years 1991 to 2020, the period the World Meteorological Organization and NOAA use for comparison. It is an average, not a forecast: most days depart from it, and some by a long way.
Where no station record is within reach, the extremes shown are the highest and lowest the reanalysis produced for the date in 1991-2020, not measured records.
Cloud, humidity, wind and sunshine come from a reanalysis: a weather model run over the past with every observation fed in, averaged over a grid cell about 50 km across. It is consistent everywhere on Earth; it smooths local detail such as a lake shore or a valley.
More for this place
Nearby
Sources
Cloud, humidity, wind and sunshine, and temperature and precipitation: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.