London’s summer weather tends to catch people off guard, especially if they expect constant rain or chilly days. You’ll usually get mild to warm temperatures—think 18°C to 25°C—with the odd hot spell nudging into the low 30s.
Long daylight hours in June let you fit in more exploring. July and August crank up the warmth, so those months usually feel like peak summer.
Rainfall stays moderate, but showers can show up with little warning. Humidity is noticeable, but not overwhelming, and the weather can flip from sunny to cloudy in no time. This mix of warmth, light, and surprise rain really shapes your plans, whether you’re wandering outdoors or ducking inside for a bit.
If you know what’s coming, you’ll pack smarter and get more out of your trip. With the right preparation, you’ll enjoy London’s parks in bloom, outdoor festivals, and those long evenings by the Thames—without getting caught by a sudden shift in the weather.
Overview of Summer Weather in London
Summer in London brings mild to warm days, the occasional shower, and plenty of daylight. You’ll find comfortable temperatures, steady but not wild rainfall, and long stretches of light that make it easy to plan outdoor adventures.
Typical Temperature Ranges
During summer, daily highs usually land between 19°C and 25°C (66°F and 77°F). July tends to bring the hottest days, and while most days feel pleasant, heatwaves can sometimes push temperatures into the low or even mid-30s Celsius (mid-80s to 90s Fahrenheit).
Nights cool down to 11°C–15°C (52°F–59°F), so you might want a light jacket after sunset, even if the afternoon felt toasty.
Humidity hangs around at moderate levels, but the city’s buildings and pavement can make it feel warmer because of the urban heat island effect. Unlike some other European cities, London rarely sees long stretches of extreme heat, so sightseeing and outdoor events usually stay comfortable.
Rainfall Patterns and Frequency
Rain happens pretty regularly in London, even in summer. June is often the wettest month, with about 40–45 mm (1.5–1.8 in) of rain spread over 12–16 days. July and August usually get a bit less, around 35–40 mm (1.3–1.6 in) each month.
Rain tends to show up as quick showers or brief bursts, not long downpours. You’ll probably see overcast skies on nearly half of summer days, but that doesn’t always mean rain will follow.
It’s smart to carry a compact umbrella or a light waterproof jacket, since showers can pop up out of nowhere. Even though it rains fairly often, summer weather rarely gets disruptive, and rain usually spreads out enough that outdoor plans aren’t totally ruined.
Daylight Hours and Sunshine
Summer in London offers some of the longest daylight hours in Europe. In June, the sun can rise before 5 a.m. and not set until after 9 p.m., so you get up to 16.5 hours of daylight. By August, daylight shortens a bit but still gives you over 14 hours.
On average, you’ll see 5–7 hours of sunshine per day, though clouds can cut into that. This balance keeps things comfortable—not too hot and never too dark.
Those long days make it easy to visit parks, markets, or landmarks. You can squeeze in more activities and still have time to relax in the evening.
Monthly Breakdown: June, July, and August
Temperatures climb steadily through early summer, with June starting off mild and July bringing the hottest days of the year. Rain falls throughout all three months, but showers don’t usually last long. Sunshine peaks in July, then drops a bit in August, while evenings stay comfortable for spending time outdoors.
June Weather Highlights
June kicks off summer in London. Average daytime highs hit about 20°C (68°F), and nights cool down to around 12°C (54°F). You’ll get up to 16 hours of daylight, so there’s plenty of time to explore.
Rain falls on roughly 14–16 days in June, but totals are moderate at about 45–55 mm. Showers usually pass quickly, so you can often get back to your plans after a short break.
Humidity sticks to moderate levels, making it comfortable for walking tours or hanging out in parks. Early mornings and evenings can feel cool, so a light jacket comes in handy.
Expect a mix of sunny spells and clouds. June isn’t the driest month, but it offers a good balance between mild temperatures and manageable rainfall.
July Weather Highlights
July usually claims the title for warmest month in London. Daytime highs average 23°C (73°F), and nights stay mild at about 14°C (57°F). Sometimes a heatwave pushes temperatures higher, but extreme heat doesn’t stick around for long.
Sunshine is at its strongest, with about 7 hours per day. July is probably your best bet for outdoor events, river walks, and open-air dining.
Rainfall is steady but not overwhelming, with around 50–60 mm spread over several days. Showers tend to be light or moderate, and clear skies usually return soon after.
Humidity stays moderate, and winds are gentle, so you get stable and pleasant weather. Warm afternoons are common, but evenings remain comfortable for being outside.
August Weather Highlights
August keeps the summer warmth going, though temperatures start to ease off. Highs average 22°C (72°F), and lows dip to about 13°C (55°F). So, August is a touch cooler than July but still great for sightseeing.
London gets 55–65 mm of rain in August, usually in short bursts. Showers might show up more often, but they rarely spoil an entire day.
Sunshine drops a bit compared to July, averaging about 6 hours daily, but you’ll still see plenty of bright afternoons. Humidity hangs around moderate levels, and breezes are usually light.
As the month goes on, evenings cool off more noticeably. If you’re out late, a light sweater or jacket will help.
Temperature Variations and Extremes
London’s summer brings mild to warm days, but daily patterns and the occasional heatwave can make a difference in how it feels. You’ll notice steady warmth during the day, cooler evenings, and sometimes a sudden spike in heat that stands out from the usual.
Day vs Night Temperatures
Daytime highs in London during summer usually fall between 19 °C and 23 °C (66 °F–73 °F). On the warmest days, temperatures can reach 25 °C (77 °F), but it rarely goes much higher. Late June through early August usually provides the most comfortable stretch, with the city’s warmest average highs.
At night, temperatures drop to about 12 °C to 16 °C (54 °F–61 °F). This cooler range makes evenings pleasant and often means you won’t need air conditioning to sleep. Nights almost never fall below 9 °C (48 °F), so you can count on consistent mildness.
The day-to-night difference usually sits around 6–8 °C, so you’ll notice a shift, but it’s not extreme. Compared to many inland cities, London’s temperature swings are pretty gentle.
| Time of Day | Average Range | Typical Low/High |
|---|---|---|
| Daytime | 19–23 °C | 14–29 °C |
| Nighttime | 12–16 °C | 9–19 °C |
Heatwaves and Unusually Hot Days
London summers are mostly moderate, but heatwaves do happen. Every so often, daytime highs shoot up into the 30–35 °C (86–95 °F) range. These spells don’t last long, but they can feel intense, especially since air conditioning isn’t all that common.
Heatwaves usually show up in July or August. Even then, they stick around for just a few days before temperatures drop back to normal. Built-up areas hold onto the heat, so you might feel it linger into the evening.
During the hottest days, London’s usual nighttime cool-off isn’t as strong. Lows can stay near 18–20 °C (64–68 °F), so nights feel warmer than usual. These hot spells don’t happen often, but if you’re sensitive to heat, it’s worth being ready.
Extreme highs above 35 °C (95 °F) are rare, but they have happened. When they do, transport and daily routines can get disrupted, so keeping an eye on the forecast helps you avoid discomfort.
Rainfall and Humidity in Summer
London’s summer weather brings a mix of mild warmth and steady moisture. You’ll get regular rainfall and noticeable humidity, but neither usually gets out of hand. These factors shape how comfortable it feels outside and how you plan your days.
Average Rainy Days Per Month
Rain falls frequently in London during summer, but it’s usually light or moderate. On average, 12–16 days per month see some rain between June and August. Showers often don’t last long, but they can show up at any time.
June is often the wettest, with totals around 40–50 mm (1.5–2 inches). July and August typically see a bit less, averaging 35–45 mm. Rain tends to be spread out, so you’ll often get sunny breaks between showers.
Since rain is so evenly distributed, a small umbrella or light rain jacket is a smart move. Streets might get slick after a sudden shower, but flooding is rare. If you’re planning outdoor sightseeing, expect some interruptions—but not total washouts.
Humidity Levels and Comfort
Humidity in London’s summer stays fairly high compared to many inland spots. Average relative humidity ranges from 70% to 80%, with mornings feeling a bit damper and afternoons slightly less so.
This level of moisture can make warm days feel heavier, especially if temperatures top 25°C (77°F). Luckily, the city’s frequent breezes help take the edge off.
Most visitors find the humidity manageable, though you’ll probably notice it more in crowded places or on the Underground. Wearing breathable clothes and drinking plenty of water will help you stay comfortable. Even in dry spells, the air rarely feels crisp, so expect a mild stickiness that’s just part of London’s maritime vibe.
What to Expect: Changeability and Packing Tips
London’s summer weather can flip quickly between sunshine, clouds, and rain. You’ll enjoy mild warmth during the day but still run into cool evenings and sudden showers, so it pays to be ready for anything.
Changeable Weather Conditions
Summer in London usually brings daytime highs between 20–24°C (68–75°F). Warm spells pop up, but they don’t last, and mornings or evenings can feel closer to 13–15°C (55–59°F).
Rain shows up frequently but is often light. You might walk in sunshine one hour and reach for your umbrella the next. Humidity can make warm days feel heavier, especially in crowds or on the Underground.
Daylight stretches long, with up to 16 hours in June, so you get plenty of time outside. Breezes along the Thames or in parks can make things feel cooler, so wearing layers is wise.
The bottom line? Expect variety. Even in a single day, you might need sunglasses, a light jacket, and a waterproof layer.
Recommended Clothing and Essentials
Pack clothes that let you adjust on the fly. You’ll definitely want a light waterproof jacket or a compact umbrella, since showers can show up out of nowhere.
Bring layers—think t-shirts, long-sleeve tops, and a light sweater or cardigan for when the evening cools down.
You’ll be walking a lot, so comfortable shoes are key. Pick shoes that work on both dry pavements and those surprise damp patches.
Here’s a quick list of essentials:
- Breathable tops for those warmer afternoons
- Light jumper or cardigan for evenings
- Foldable rain jacket or umbrella
- Comfortable walking shoes
- Small day bag for carrying your layers
If you want to blend in, skip the heavy outdoor gear when you’re in the city. Locals usually dress casually but keep it neat, wearing practical clothes that fit both work and downtime. That balance really helps you stay comfortable and ready for anything.
Best Time to Visit London for Summer Weather
London’s summer brings warm days, long daylight, and tons of outdoor events. The best time to visit really depends on whether you prefer milder weather for sightseeing or want the heat for parks, festivals, and open-air fun.
Ideal Months for Outdoor Activities
June, July, and August make up London’s official summer. June usually offers the best balance, with average highs around 21°C (70°F) and fewer crowds than you’ll see later on. Days feel long, with the sun up before 5 am and setting after 9 pm near the solstice.
July gets the warmest, with highs close to 23°C (73°F). You’ll find open-air theatre, rooftop bars, and cycling tours in full swing. It does still rain on about 7 days, so a light waterproof layer is a smart move.
August stays warm, about the same as July. Big events like the Notting Hill Carnival happen then, so the city feels extra lively and crowded. If you love energetic festivals, August is your month.
| Month | Avg High | Avg Low | Days of Rain |
|---|---|---|---|
| June | 21°C / 70°F | 13°C / 55°F | 8 |
| July | 23°C / 73°F | 15°C / 59°F | 7 |
| August | 23°C / 73°F | 15°C / 59°F | 8 |
Balancing Weather and Crowds
If you’re hoping for great weather but don’t want to deal with swarms of tourists, early June usually hits that sweet spot. The days feel long, temperatures stay comfortable, and hotels tend to cost a bit less than they do right in the middle of summer.
By July and August, London fills up fast. The crowds at places like the Tower of London or the British Museum can get pretty intense, and hotel prices climb. Sure, the weather’s warmer, but honestly, all the people milling around can make sightseeing a bit of a slog.
If you’d rather take things easy, try late August into early September. The weather’s still mild, but you’ll notice the city starts to quiet down. It’s a nice window for outdoor stuff and getting into the big sights without sacrificing that pleasant summer vibe.