May is one of the best months to visit London: days are long and often sunny, average highs reach about 18°C, and the parks are at their greenest. In 2027 the month has two bank holiday weekends (3 May and 31 May) and the RHS Chelsea Flower Show on 18-22 May, so plan around those dates if you want quieter streets.
The weather in May is milder and more settled than in spring, although it is not yet summer. Sunshine hours are almost as high as in June, but nights are still fresh and a cool, grey day is always possible.
Crowds are moderate for most of the month. They build on the two long weekends and in the last days of May, when London's schools break up for their half-term holiday. For the rest of the time, May gives you summer-like conditions without summer prices.
Key facts for May 2027
- Average high / low
- 18.4°C / 9.1°C (Met Office, Heathrow, 1991-2020)
- Sunshine
- About 207 hours
- Rain
- 45.9 mm on about 8 days
- Bank holidays
- Monday 3 May (Early May) and Monday 31 May (Spring)
- Half-term
- Monday 31 May to Friday 4 June in Lambeth (dates vary by borough)
- Main event
- RHS Chelsea Flower Show, 18-22 May 2027
Warm afternoons, fresh evenings: May's weather in figures
The Met Office's long-term averages for Heathrow show a May average high of 18.4°C and an average low of 9.1°C, more than three degrees warmer than April by day. Frost has virtually disappeared. Sunshine averages about 207 hours, only a fraction less than June's 208.
Rain falls on about eight days in the month, adding up to 45.9 mm. That is not much, but May weather can change within a day: a warm, bright lunchtime in a park can be followed by a chilly evening at 10°C. If you plan to eat or drink outside after dark, take a layer.
Central London usually runs a little warmer than Heathrow. For the whole-year picture, see our guide to London's climate and what to wear.
Two long weekends: 3 May and 31 May 2027
England has two bank holidays in May, both on Mondays. In 2027 they are the Early May bank holiday on 3 May and the Spring bank holiday on 31 May. On both weekends many Londoners go away, while visitors from the rest of the UK come in, so central attractions tend to be busy and trains out of London fill up on the Friday evening.
Most sights open on bank holidays, often with weekend hours. The free Sky Garden, for example, uses its weekend hours (11:00-21:00) on bank holidays, and its free tickets, normally released every Monday, are not released on bank holiday Mondays. Shops, banks and some transport services run differently, which our guide to bank holiday opening hours explains.
Sky Garden bookings shift in bank holiday weeks. Free tickets are released on Monday mornings three weeks ahead, but not when that Monday is a bank holiday. If you want a slot in early June 2027, look at the official booking page for the release date rather than assuming it is Monday 31 May.
The RHS Chelsea Flower Show, 18-22 May 2027
The Chelsea Flower Show is the best-known garden show in Britain, held by the Royal Horticultural Society in the grounds of the Royal Hospital Chelsea. Designers build show gardens that last only a week, and nurseries fill the Great Pavilion with plants.
In 2027 it runs from Tuesday 18 to Saturday 22 May. The first two days (18 and 19 May) are for RHS members only; the public days are Thursday 20 to Saturday 22 May. Tickets go on sale in October 2026, so book as early as you can. Our guide to the Chelsea Flower Show covers tickets, times and how to get there.
Public days run from 08:00 to 20:00, except the last day, when the show closes at 17:30 and ends with the Great Plant Sell Off (16:00-17:30). There is also an evening Chelsea Late on Friday 21 May, 17:30-22:00. Expect Chelsea and the streets around the Royal Hospital to be crowded all week. If you do not get a ticket, Columbia Road's Sunday flower market in east London is a cheaper way to spend a morning among plants.
Half-term at the end of the month
London's schools take a one-week break at the end of May. In Lambeth it runs from Monday 31 May to Friday 4 June 2027; other boroughs and private schools set their own dates. Because it starts on the Spring bank holiday, the last weekend of May becomes the start of a nine-day holiday for many families.
During half-term, family attractions, the free museums in South Kensington and the zoo are much busier than in the rest of May. If you have a choice, come in the middle of the month. If you are travelling with children, half-term is still manageable with pre-booked tickets and an early start.
Parks, lidos and outdoor swimming
May is when London starts living outdoors. Lunchtime crowds spread across the lawns, park cafés put tables outside and the long evenings (sunset is around 21:00 by the end of the month) make a picnic after work a common sight.
In Hyde Park and Kensington Gardens, the Serpentine Lido usually opens for weekend sessions from mid-May, before the full season from June. In 2026 an adult full-day ticket cost £8.40; the Royal Parks publishes current prices and dates. The Diana Memorial Playground stays open until 19:45 from May to August.
For wilder swimming, the bathing ponds on Hampstead Heath are popular on warm days. Their online booking system was closed in autumn 2026 and was due to reopen in spring 2027, so check the City of London's swimming pages before you go.
Rules for dogs and deer from 1 May
May to July is the season when deer give birth in Richmond Park and Bushy Park. From 1 May to 31 July, dogs must be kept on leads in all areas of Richmond Park. Everyone should stay at least 50 metres from the deer. The Royal Parks advises dog walkers to keep to the edges of the park in this season and avoid long grass and bracken, where newborn deer may be hidden.
Feeding the deer is illegal all year. If you want photographs, use a zoom lens and stay on the main paths.
Stay out of the bracken in Richmond Park until the end of July. Newborn deer lie hidden there, and deer feel threatened by people and dogs at close range. Keep to the main paths, never touch a young deer, and take photos from at least 50 metres away.
Rehearsals and the run-up to Trooping the Colour
Trooping the Colour, the King's Birthday Parade, normally takes place in June, but the preparations start earlier. In 2026 the three ticketed events at Horse Guards Parade (the parade itself and two reviews) were held on 30 May, 6 June and 13 June. The 2027 dates had not been announced when we checked in September 2026. If a review falls in late May, you may see soldiers and bands marching along The Mall on a Saturday morning.
Grandstand seats are allocated by ballot, but you can watch from The Mall and St James's Park free. Our Trooping the Colour guide explains how the ballot works, and the Changing of the Guard page covers the regular ceremony, whose dates vary from month to month.
Day trips when the weather is good
Long May days are ideal for getting out of the city. The Seven Sisters cliffs on the Sussex coast are at their best on a clear day; the National Trust warns that the cliffs "can collapse without warning", so keep well back from the edge. Inland, the villages of the Cotswolds look their best in late spring, before the peak summer coach tours.
Avoid the bank holiday weekends for day trips if you can. Trains are fuller, and popular countryside car parks fill early.
What to pack and how to get around
- Layers: a T-shirt for the afternoon and a light jumper or jacket for the evening.
- A compact umbrella or a thin waterproof; a full winter coat is no longer needed.
- Sunglasses and sun cream for long days in the parks.
- Comfortable shoes: May is a month for walking.
Cycling is a pleasant way to see the parks in good weather. A Santander Cycles hire costs £1.65 for up to 30 minutes, and a day pass starts at £3.50; our guide to hire bikes and cycling in London explains how it works. On a warm evening, one of London's rooftop bars is a good place to watch the late sunset, but book ahead at weekends.
Because May is popular, rooms go quickly around the bank holidays and Chelsea week. Read our advice on booking safely and avoiding accommodation scams, then compare this month with April, which is cooler and quieter, and June, which has even longer evenings.
Frequently asked questions
Is May a good month to visit London?
Yes. May has long, often sunny days, average highs of about 18°C and less crowding than July and August. The busiest times are the two bank holiday weekends (3 May and 31 May 2027), Chelsea Flower Show week and the half-term week at the end of the month.
What are the bank holidays in London in May 2027?
There are two: the Early May bank holiday on Monday 3 May and the Spring bank holiday on Monday 31 May 2027. Most attractions stay open, often with weekend hours, but transport timetables and some shop hours change.
When is the Chelsea Flower Show in 2027?
The RHS Chelsea Flower Show runs from 18 to 22 May 2027. Tuesday 18 and Wednesday 19 May are for RHS members; the public days are Thursday 20 to Saturday 22 May. Tickets go on sale in October 2026.
How warm is London in May?
The Met Office average for Heathrow is a high of 18.4°C and a low of 9.1°C, with about 207 hours of sunshine. Afternoons can feel warm in the sun, but evenings are cool, so pack a light jacket or jumper.
Sources
- Met Office - Heathrow climate averages 1991-2020 (checked September 2026)
- GOV.UK - UK bank holidays (checked September 2026)
- Royal Horticultural Society - RHS Chelsea Flower Show (checked September 2026)
- Lambeth Council - School term dates 2026 to 2027 (checked September 2026)
- The Royal Parks - Richmond Park FAQs (checked September 2026)
- The Royal Parks - Serpentine Lido swimming (checked September 2026)
- Sky Garden - Booking (checked September 2026)
- Household Division - Trooping the Colour (checked September 2026)