London weather in May usually feels like settled spring rather than full summer. Days are long, parks are green, and outdoor sightseeing becomes more comfortable, but cool mornings, warm spells, and wet periods can all occur. The easiest way to prepare is to pack adaptable layers rather than clothes for one fixed temperature.
Quick Answer
Met Office 1991–2020 Heathrow normals put May at an average high of 18.37°C (65.1°F), low of 9.08°C (48.3°F), 45.91 mm of rain, about eight days with at least 1 mm of rain, and 207.49 hours of sunshine. Bring layers, light rain protection, and comfortable walking shoes.
Last checked: October 1, 2026. Dates and figures were verified against official sources.
Key Takeaways
- The weather figures in this guide use Heathrow’s Met Office 1991–2020 climate normals, which are useful for planning but are not a forecast for your exact travel dates.
- London has two bank holidays in May 2027: Monday, May 3 and Monday, May 31, when attractions and transport can be busier.
- The RHS Chelsea Flower Show runs May 18–22, 2027, adding extra demand around Chelsea during that week.
- May can produce exceptional heat despite its mild averages: Kew Gardens reached a UK May record of 35.1°C on May 26, 2026.
- For most trips, a light waterproof layer, sweater or cardigan, comfortable shoes, and clothes that can be added or removed are more useful than a heavy coat.
Average Temperature in London in May
London is generally mild in May, with comfortable afternoons and noticeably cooler mornings and evenings. The Met Office Heathrow 1991–2020 climate normals give an average daily maximum of 18.37°C (65.1°F) and an average minimum of 9.08°C (48.3°F).
These figures are long-term averages, not a promise that every day will stay between 9°C and 18°C. A particular May can include cool, gray days as well as much warmer spells, so check the short-range forecast shortly before your trip.
| May climate measure | Heathrow 1991–2020 normal |
|---|---|
| Average daily maximum | 18.37°C / 65.1°F |
| Average daily minimum | 9.08°C / 48.3°F |
| Monthly rainfall | 45.91 mm / 1.81 in |
| Days with at least 1 mm of rain | 8.00 days |
| Monthly sunshine | 207.49 hours |
May therefore works well for walking, sightseeing, parks, markets, and outdoor dining. Still, a light extra layer is useful if you leave your hotel early or plan to stay outside after sunset.
Rainfall in London in May
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London is not rain-free in May, but the long-term total is moderate. Heathrow averages 45.91 mm of rainfall during May and about eight days on which at least 1 mm falls.
That rain-day figure does not mean it rains continuously for eight full days. It simply means measurable rain of at least 1 mm was recorded on those dates. A forecast showing rain should therefore be read alongside the hourly forecast rather than treated as proof that an entire sightseeing day will be lost.
May is among London’s drier months by long-term rainfall totals, but weather can still vary sharply from one year to another. Carrying a compact umbrella or light waterproof jacket gives you enough flexibility for most city activities without requiring heavy rain gear.
What to Wear in London in May
The best clothing for London in May is a set of light layers that you can adjust during the day. A morning near the long-term minimum can feel cool, while sunshine and walking can make the afternoon feel much warmer.
- Base layer: T-shirts, shirts, blouses, or other breathable tops.
- Warm layer: A light sweater, cardigan, or thin fleece for mornings and evenings.
- Outer layer: A light waterproof jacket, trench coat, or similar rain-resistant layer.
- Bottoms: Jeans, trousers, chinos, skirts, or dresses that work with an extra layer if needed.
- Shoes: Comfortable, broken-in walking shoes with reasonable grip for wet pavement.
- Day bag: A compact umbrella, sunglasses, and space for a layer you remove during warmer periods.
A bulky winter coat is usually unnecessary for typical May conditions. Shorts and sandals can be comfortable during a warm spell, but they should not be your only options because evenings and wet days may feel much cooler.
Outdoor Activities in London in May
May is one of the most convenient spring months for exploring London outdoors because mild temperatures combine with increasingly long days. In 2027, daylight in the City of London increases from about 14 hours 48 minutes on May 1 to about 16 hours 15 minutes on May 31.
Hyde Park, Regent’s Park, St James’s Park, Kensington Gardens, and Richmond Park all work well for walking or picnics. In Hyde Park, boating on the Serpentine is another weather-dependent option, while riverside walks along the Thames let you combine outdoor time with nearby indoor attractions if showers arrive.
Markets are also easy to include on a mild day. Borough Market can be combined with a walk along the South Bank, while neighborhoods such as Notting Hill, Greenwich, and Covent Garden are comfortable to explore on foot when conditions are dry.
Because the evenings stay light, you do not need to fit every outdoor activity into the middle of the day. Museums and indoor attractions can fill cooler or wetter hours, leaving brighter periods for parks, river walks, and neighborhood exploring.
Events and Festivals in London in May
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May’s event calendar can affect both what you can do and how crowded parts of London feel. For a 2027 trip, the two dates most worth building around are the bank holiday weekends and RHS Chelsea Flower Show week.
RHS Chelsea Flower Show
The RHS Chelsea Flower Show runs May 18–22, 2027 at Royal Hospital Chelsea. May 18 and 19 are RHS members’ days, while public days run from Thursday, May 20 through Saturday, May 22.
The show brings major displays of garden design, plants, floristry, and horticulture to Chelsea. Even if the event is not part of your itinerary, expect the surrounding area to be busier during show week.
May Bank Holidays and Half-Term
According to GOV.UK’s England and Wales bank-holiday calendar, the Early May bank holiday falls on Monday, May 3, 2027, and the Spring bank holiday falls on Monday, May 31, 2027. Long weekends can increase demand at major attractions, parks, rail stations, and popular day-trip destinations.
Visit London’s 2027 May half-term guide lists the break as May 31 to June 4. Individual schools can set different dates, but families traveling at the end of the month should expect many child-focused attractions to be busier.
London Craft Week
London Craft Week is another spring event associated with May, bringing exhibitions, demonstrations, workshops, talks, and displays of craftsmanship to venues around the city. Its program can include fashion, jewelry, furniture, ceramics, textiles, and other disciplines, giving visitors an indoor option when the weather is less cooperative.
Spring Flowers and Greenery in London in May
May is a strong month for London’s gardens because spring flowering overlaps with fresh summer growth. Exact bloom dates vary with each year’s weather, so one species may peak earlier or later than it did the previous year.
At Kew Gardens, the Rhododendron Dell is at its prime in April and May. Wisteria, late spring flowers, fresh leaves, and developing summer planting also add color across gardens and residential streets during the month.
Other good places for seasonal greenery include Regent’s Park, St James’s Park, Richmond Park, Kensington Gardens, and neighborhood garden squares. For photography, a bright period after rain can produce richer colors and reflections without requiring a completely cloudless day.
What to Do on Rainy Days in London
A rainy May day does not need to become a lost sightseeing day because many of London’s major attractions are indoors. The simplest plan is to keep at least one museum, gallery, market, or covered attraction available for a wet part of your itinerary.
The British Museum is a useful central option, while the Natural History Museum’s main galleries are free to explore. The Natural History Museum recommends booking a free entry ticket if you want to guarantee admission during busy periods.
Cafés, covered markets, galleries, department stores, and West End performances can also fill a wet afternoon. If the weather improves later, London’s long May evenings often leave enough daylight to return outside for a walk.
Historical Weather Patterns in London in May
Long-term averages describe typical conditions, but individual Mays can be dramatically different. The strongest recent example is the extraordinary late-May heat of 2026.
The Met Office confirmed that Kew Gardens reached 35.1°C on May 26, 2026, setting a new UK May daily maximum-temperature record. The previous May record had been 32.8°C, recorded in 1922 and again in 1944.
This does not mean travelers should expect temperatures in the 30s every May. Instead, it shows why an average high of about 18°C should be treated as a planning baseline rather than a limit on what the weather can do.
Climate Change and London Weather in May
London’s warming climate increases the importance of preparing for occasional spring heat as well as normal cool and wet conditions. Climate change does not make every May identical or guarantee that each year will be warmer than the previous one.
The Met Office State of the UK Climate 2025 report says the most recent UK decade, 2016–2025, was 0.51°C warmer than 1991–2020. It also reports that the number of days above 30°C and nights above 18°C in Greater London more than quadrupled in 2016–2025 compared with 1961–1990.
For a visitor, the practical lesson is simple: use climate averages for packing, but check the actual forecast for your dates. A May suitcase should be able to handle both cool rain and unexpectedly warm weather without requiring a complete change of wardrobe.
How to Make the Most of London Weather in May
May gives you a useful balance of mild temperatures, long daylight, green parks, spring flowers, and a busy cultural calendar. Plan outdoor activities around the better parts of each day’s forecast rather than assuming the whole day will be wet or dry.
If your trip overlaps May 3, May 18–22, or the late-May bank holiday and half-term period, allow extra time for busy attractions and transport. Outside those periods, May’s mild climate and long evenings make it easy to combine indoor and outdoor sightseeing in the same day.
Frequently Asked Questions
What is the weather like in London in May?
London is generally mild in May, with cool mornings and comfortable afternoons. Heathrow’s 1991–2020 averages are 18.37°C for the daily maximum and 9.08°C for the minimum. Rain and warm spells are both possible, so climate averages should be used as a guide rather than a forecast.
What type of clothing should I pack for London in May?
Pack light layers, a sweater or cardigan, a light waterproof jacket, and comfortable walking shoes. A compact umbrella is useful for wet periods. Most travelers do not need a heavy winter coat, but having an extra layer for cool mornings and evenings makes sightseeing more comfortable.
What activities are popular in London in May?
Popular May activities include walking through London’s parks, visiting gardens, taking river walks, exploring outdoor markets, and boating when conditions allow. RHS Chelsea Flower Show is a major May event, while museums and galleries provide easy alternatives during cooler or wetter periods.
Does London experience extreme weather in May?
Extreme May weather is unusual, but it can happen. Kew Gardens reached 35.1°C on May 26, 2026, setting the UK May maximum-temperature record. That was an exceptional event rather than typical May weather, so visitors should still plan around the much milder long-term averages.
How much does it rain in London in May?
Heathrow averages 45.91 mm of rainfall in May under the Met Office 1991–2020 climate normals. About eight days record at least 1 mm of rain. A rain day does not mean continuous rain for 24 hours, so hourly conditions matter when planning outdoor activities.
Does it snow in London in May?
Snow is highly unusual in London in May. Heathrow’s 1991–2020 climate normal records only 0.03 days of air frost during the month, so wintry conditions are not something most May visitors need to pack for. Cool rain is a far more practical concern.
Is May a good time to visit London?
May is a practical time to visit London if you want mild weather, long days, green parks, and a mix of indoor and outdoor activities. The main tradeoffs are changeable weather and higher crowds around bank holidays, Chelsea Flower Show week, and the late-May school half-term period.
When are the May bank holidays in London in 2027?
The Early May bank holiday is Monday, May 3, 2027, and the Spring bank holiday is Monday, May 31, 2027. Attractions, parks, and transport hubs can be busier around both long weekends, while some businesses and transport services may operate different schedules.
If you’re planning a trip to London in May, you may want to check out this article on London Weather in May: Mild Temps & Rainfall. For more information on travel tips and weather forecasts, visit this link.
Sources
- Met Office — Heathrow long-term averages: 1991–2020 May temperature, rainfall, rain-day, frost, and sunshine normals.
- Met Office — May 2026 temperature records verified: UK May temperature record at Kew Gardens.
- GOV.UK — UK bank holidays: England and Wales bank-holiday dates for May 2027.
- Royal Horticultural Society — RHS Chelsea Flower Show: 2027 show dates and members’ and public days.
- Visit London — May half-term 2027: late-May school-break dates and visitor planning information.
- Royal Botanic Gardens, Kew — Rhododendron Dell: April and May flowering season at Kew.
- Natural History Museum — Plan your visit: free gallery entry and visitor booking guidance.
- Met Office — State of the UK Climate: recent UK warming and Greater London temperature-extreme trends.
- SunToday — London sunrise and sunset times for May 2027: daylight length across the month.
