Weather in United Kingdom in December

December climate overview

Daytime highs across United Kingdom in December run from 7.7°C (London) to 9.7°C (Cornwall). Days over 25°C are rare anywhere in United Kingdom in December. Nights average 4.3°C; the coldest 10% of nights in London fall to -2°C or below.

Rainfall in December

Expect around 13 rainy days (1 mm or more) in December, with London the driest (11 days) and Cornwall the wettest (16 days). The wettest December at Cornwall between 1991 and 2020 was 2020 with 201 mm; the driest was 2016 with 25 mm.

Sea temperature

The sea averages 11.0°C around United Kingdom in December. That is cold for swimming without a wetsuit.

Sunshine and daylight

Around 2.2 hours of sunshine a day on average, out of 7.8 hours of daylight (sunshine estimated from cloud cover).

December against the rest of the year in United Kingdom

December is the 10th warmest month of the twelve in United Kingdom. It is 2.3°C cooler than November and 0.4°C cooler in January. The hottest month here is July (20°C) and the coolest January (8°C).

Which part of United Kingdom in December?

• Most sunshine: Cornwall, 2.2 h a day.
• Driest: London, about 11 rainy days.
• Warmest sea: Cornwall, 11°C.
• Hottest: Cornwall, 10°C by day.
• Coolest (better for walking and cities): London, 8°C.

What to pack for United Kingdom in December

Based on the averages: proper layers and a jacket - daytime highs average only 9°C; a warm layer for evenings, when it drops to around 4°C; a rain jacket - roughly 13 wet days.

Similar weather elsewhere in December

Within 1.5°C of United Kingdom's December daytime average: Istanbul (10°C, sea 11°C), Florence (10°C), Madrid (10°C), Lido di Jesolo (8°C, sea 12°C), Sunny Beach (8°C, sea 10°C). See the full ranking for December.

Cornwall for milder weather, London for fewer rainy days

Cornwall is the warmer choice, averaging 10°C by day and 6°C at night. That makes it a better fit if you want outdoor time without quite such cold evenings, but its 16 rainy days mean you should keep plans flexible. London is cooler at 8°C by day and 3°C at night, so a warm coat matters, especially when staying out after dark. Its 11 rainy days give it the advantage if avoiding wet weather is your priority, though dry conditions are far from assured. The choice is a trade-off: Cornwall for milder air, London for less frequent rain, rather than either destination for dependable outdoor weather.

Expect limited sunshine and dress for damp days

With average sunshine of 2.2 hours, December is not a month to plan around long spells in the sun. Keep outdoor plans movable and have an indoor alternative rather than committing to a full day outside regardless of conditions. Wear layers beneath a waterproof coat, with footwear that can cope with rain; gloves and a warm hat are sensible for evenings. Cornwall's sea temperature of 11°C also puts beach-holiday expectations out of reach for most travellers. Coastal time is better approached as a walk dressed for the weather than a casual swim. This month suits travellers comfortable adapting their plans, not those seeking warmth.