Climate averages 1991–2020
Portsmouth weather
in December.
A cool, wet month: the 10th warmest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cool month in Portsmouth: daytime highs average 8.4°C and nights cool to about 4.3°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 92 mm of rain on roughly 13 days, which makes December a wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 8 h 03 min on an average December day.
The nearest other city in this atlas is Southampton (25 km away). In December its highs average 8.3°C, about as warm as Portsmouth, with 71 mm of rain.
Among the 143 cities listed in the United Kingdom, Portsmouth ranks joint 7th of 143 for the warmest December highs and 116th of 143 for the driest December (rainfall, lowest first). The mean December high of those 143 cities is 7.2°C; Portsmouth is 1.3°C warmer than that mean.
From December to January, average highs fall by 0.5°C to 7.9°C, and monthly rainfall falls from 92 mm to 83 mm.
The annual picture
December in context
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
Portsmouth climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 7.9°C3.7°C | 3.7°C | 83 | 13.4 | 8.58 h |
| February | 8.1°C3.3°C | 3.3°C | 61 | 10.6 | 10.010 h |
| March | 10.3°C4.4°C | 4.4°C | 50 | 10.0 | 11.812 h |
| April | 12.9°C6.0°C | 6.0°C | 52 | 9.7 | 13.814 h |
| May | 16.0°C9.0°C | 9.0°C | 50 | 9.1 | 15.515 h |
| June | 18.7°C11.8°C | 11.8°C | 51 | 9.4 | 16.416 h |
| July | 20.8°C14.0°C | 14.0°C | 52 | 9.6 | 16.016 h |
| August | 20.6°C14.1°C | 14.1°C | 64 | 9.9 | 14.515 h |
| September | 18.3°C12.2°C | 12.2°C | 62 | 10.2 | 12.713 h |
| October | 14.7°C9.7°C | 9.7°C | 96 | 13.4 | 10.811 h |
| November | 11.0°C6.5°C | 6.5°C | 99 | 13.8 | 9.09 h |
| December, selected | 8.4°C4.3°C | 4.3°C | 92 | 13.4 | 8.08 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
December in nearby cities
- Southampton in DecemberUnited Kingdom · 25 kmHigh 8.3°C · Low 4.2°C · 71 mm rain
- Worthing in DecemberUnited Kingdom · 50 kmHigh 8.5°C · Low 4.8°C · 99 mm rain
- Basingstoke in DecemberUnited Kingdom · 52 kmHigh 7.4°C · Low 2.7°C · 64 mm rain
- Bournemouth in DecemberUnited Kingdom · 56 kmHigh 8.7°C · Low 5.3°C · 78 mm rain
- Guildford in DecemberUnited Kingdom · 61 kmHigh 7.8°C · Low 2.9°C · 62 mm rain
- Poole in DecemberUnited Kingdom · 64 kmHigh 8.9°C · Low 5.4°C · 78 mm rain
- Hove in DecemberUnited Kingdom · 65 kmHigh 8.4°C · Low 4.7°C · 103 mm rain
- Brighton in DecemberUnited Kingdom · 67 kmHigh 8.3°C · Low 4.6°C · 103 mm rain
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 limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Portsmouth) is explained once on the Portsmouth year overview and on the Sources, method and limits page.