Weather in United Kingdom in May

May climate overview

Daytime highs across United Kingdom in May run from 14.9°C (Cornwall) to 16.6°C (London). Even in London only 1% of days reach 25°C. Nights average 8.8°C; the coldest 10% of nights in Cornwall fall to 6°C or below.

Rainfall in May

Expect around 11 rainy days (1 mm or more) in May, with London the driest (10 days) and Cornwall the wettest (13 days). The wettest May at London between 1991 and 2020 was 2007 with 107 mm; the driest was 2020 with 5 mm.

Sea temperature

The sea averages 11.8°C around United Kingdom in May. That is cold for swimming without a wetsuit.

Sunshine and daylight

Around 5.2 hours of sunshine a day on average, out of 15.4 hours of daylight (sunshine estimated from cloud cover).

May against the rest of the year in United Kingdom

May is the 5th warmest month of the twelve in United Kingdom. It is 2.8°C warmer than April and 2.7°C warmer in June. The hottest month here is July (20°C) and the coolest January (8°C).

Which part of United Kingdom in May?

• Most sunshine: Cornwall, 5.3 h a day.
• Driest: London, about 10 rainy days.
• Warmest sea: Cornwall, 12°C.
• Hottest: London, 17°C by day.
• Coolest (better for walking and cities): Cornwall, 15°C.

What to pack for United Kingdom in May

Based on the averages: proper layers and a jacket - daytime highs average only 16°C; a warm layer for evenings, when it drops to around 9°C; a rain jacket - roughly 11 wet days.

Similar weather elsewhere in May

Within 1.5°C of United Kingdom's May daytime average: Amsterdam (16°C, sea 13°C). See the full ranking for May.

London for warmer days and less rain

London suits travellers who want the warmer option without expecting hot weather. Its May daytime average is 17°C, making a light layer a sensible starting point for time outdoors. Nights average 8°C, so keep something warmer for evenings rather than assuming daytime comfort will last. With 10 rainy days, London has less frequent rain than Cornwall, but a waterproof jacket and flexible outdoor plans still make sense. Heat is not the main concern: only 1% of days exceed 25°C. Choose London over Cornwall if a little extra daytime warmth and fewer rainy days matter more to you than being beside the sea.

Cornwall for coastal time, not warm-water swimming

Cornwall is the cooler choice by day, averaging 15°C, though its nights are slightly milder than London's at 9°C. That makes it better suited to travellers happy to spend time by the coast in layers than those seeking a summer-style beach holiday. Rain occurs on 13 days, so leave room to adjust outdoor plans and bring a waterproof outer layer. The sea averages 12°C: do not mistake a comfortable spell on land for warm swimming conditions. If swimming is central to your holiday, May is a poor fit for warm-water expectations. If coastal time matters more than heat, the cooler conditions may suit you.