Weather in London in May

A good month. May works. It is not the peak, but nothing about it fights you. Highs average 17.3 °C, lows 7.6 °C, and rain falls on 11 days — nothing in the month is working against you.

May ranks 5 of 12 in London: past the worst of the year but short of September, which is the month to book if the dates are open.

Rain on 11 days, 1 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 17.3 °C days and 7.6 °C nights; the spread matters more here than any single number.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest May day reached 26.8 °C and the coldest night fell to -0.1 °C, and the wettest single day dropped 28 mm — roughly 51% of the month's rain in one day.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 109 mm against 4 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 55 mm average is a reasonable planning figure, not a promise.

Wind is light at 11.4 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 79%, high enough to notice on the warm days without dominating them.

How May sits in the year

The month is on the way up: 3 °C warmer than April, and June adds another 3.2 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in May

15.6 hours of daylight, gaining 1.5 hours across the month. That is between London's extremes of 16.6 and 7.9 hours, so days are long enough not to constrain the plan.

An inland climate

Despite being inland, the year stays fairly even: 21.1 °C between the year's warmest afternoons and coldest nights.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

May in London versus nearby

If London is one option among several, the nearby comparison is worth making. Birmingham is close enough to be a coin toss — within a degree on temperature, 1 day more rain. Le Havre is close enough to be a coin toss — within a degree on temperature, 1 day more rain.

So: May works, with September the better month by 12 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in London

See all twelve months in London, or where else to go in May.