United Kingdom London Weather in September — Climate Guide
September in London is Very Good
September is Very Good for London.
London's second sweet spot — schools back, crowds drop slightly, weather still mild. Open House London on the 3rd weekend opens 800+ buildings to the public for free — usually inaccessible private clubs, government buildings, and architectural gems. London Fashion Week (mid-Sep) brings the trendy set; hotels near Soho/Mayfair pricier that week. Best value month overall.
Travel score
Early autumn + quieter museums + Korean Chuseok
September Weather at a Glance
September averages 66°F / 19°C highs and 54°F / 12°C lows — early autumn. 9 rainy days, 50mm. Humidity 75% + 5 hours of sunshine. Daylight shortens to 12 hours. Year's 2nd-best season.
September Travel Advice
Long sleeves + cardigan + umbrella. 2nd weekend of September Open House Festival (London 800+ normally-closed buildings free + #1 cultural event). London Fashion Week (mid-September, 5 days, SS collections) signature. Late September foliage starts.
Flying In from Overseas
Korean Chuseok (varies by year, mid-September to early October) — Asia-London $1,050-1,680 round-trip. Post-Chuseok value.
September Pricing Trends
Early autumn — Covent Garden 3-star $280-455/night. Chuseok week some uptick.
London September Weather Stats
Avg High
19°C
Avg Low
11°C
Rainy Days
8
50mm total
Sunshine
5h
Daily avg
Humidity
70%
Mild
UV Index
4
Moderate
Wind
13 km/h
Gusts 25
Sea Temp
17°C
Avg water temp
Crowds
Busy
At attractions
September Sunrise & Sunset
Air Quality
PM2.5
21 μg/m³
PM10
32 μg/m³
Status
Moderate
Feels-Like Temperature & Wind
Feels like
Daytime
18°C
Nighttime
10°C
Humidity and wind affect how the actual temperature feels.
Wind
13 km/h
Max gust 25 km/h
Activities Recommended for September
September Travel Pros & Cons
Pros
- Best value month (schools back)
- Open House London (free)
- Last warm pub gardens
- Theater season opens
Cons
- First week still school-holiday crowded
- Rain picks up
- Days shortening rapidly
September Events & Festivals
- Open House London (3rd weekend, free building tours)
- London Fashion Week (mid-Sep)
- The Mayor's Thames Festival
London in September — Full Picture
London's second sweet spot — schools back, crowds drop slightly, weather still mild. Open House London on the 3rd weekend opens 800+ buildings to the public for free — usually inaccessible private clubs, government buildings, and architectural gems. London Fashion Week (mid-Sep) brings the trendy set; hotels near Soho/Mayfair pricier that week. Best value month overall.
What to Wear & What to Pack
Light jacket, jeans, sweater for evenings. Umbrella back in the bag — rain picks up. Sunshine still good through mid-month.
Packing Checklist
Seasonal Weather Overview
Spring (Mar·Apr·May)
14°C
6.3°C
8.7/mo
Summer (Jun·Jul·Aug)
21.7°C
13.3°C
6.7/mo
Autumn (Sep·Oct·Nov)
Current15°C
8°C
9.3/mo
Winter (Dec·Jan·Feb)
8.3°C
2.3°C
10.3/mo
London Monthly Weather Comparison
| Month | High | Low | Rain | Sun | Humid | UV | Crowd | Price |
|---|---|---|---|---|---|---|---|---|
| 8° | 2° | 11d·55mm | 1.5h | 80% | 1 | Quiet | Low season | |
| 9° | 2° | 9d·40mm | 2h | 78% | 2 | Quiet | Low season | |
| 11° | 4° | 9d·40mm | 3.5h | 73% | 3 | Moderate | Shoulder | |
| 14° | 6° | 9d·45mm | 5h | 70% | 4 | Moderate | Shoulder | |
| 17° | 9° | 8d·45mm | 6.5h | 68% | 5 | Busy | Peak | |
| June (Best) | 20° | 12° | 7d·45mm | 7h | 65% | 6 | Busy | Peak |
| July (Best) | 23° | 14° | 6d·45mm | 7h | 65% | 6 | Very busy | Peak |
| 22° | 14° | 7d·50mm | 6.5h | 66% | 5 | Very busy | Peak | |
| 19° | 11° | 8d·50mm | 5h | 70% | 4 | Busy | Peak | |
| 15° | 8° | 10d·70mm | 3.5h | 76% | 3 | Moderate | Shoulder | |
| 11° | 5° | 10d·65mm | 2h | 79% | 1 | Moderate | Shoulder | |
| 8° | 3° | 11d·55mm | 1.5h | 81% | 1 | Very busy | Peak |
View Other Months
London September Hotel Picks
Frequently Asked Questions
Is September a good time to visit London?
London in September is Very Good. Tourist crowds are busy and flight/hotel prices are peak.
What's the average temperature in London in September?
London September averages a high of 19°C and a low of 11°C.
Does it rain much in London in September?
London September averages 50mm of rainfall over about 8 rainy days.
What should I wear in London in September?
Light jacket, jeans, sweater for evenings. Umbrella back in the bag — rain picks up. Sunshine still good through mid-month.
What time are sunrise and sunset in London in September?
London September sunrise is 06:30 and sunset is 19:20, with 12h 50m of daylight.
What's the air quality like in London in September?
London September air quality (AQI) averages 48, rated Good. PM2.5 averages 21μg/m³.
What activities are recommended in London in September?
In September, London is great for Open House London (free tours), London Fashion Week, Outdoor pubs (last good weeks).
Is September peak season in London?
London September crowds are busy and prices are peak. Advance reservations are strongly recommended.
Best Months to Visit London
View Other Months
Why you can trust weather guide
Based in Chiang Mai for 8+ years, with 30+ countries visited across Southeast Asia, Japan, and Europe. Every detail in this guide is primary-source verified as of April 2026, with prices auto-refreshed via live exchange rate APIs. This isn't AI-generated boilerplate — it's written from the perspective of someone who has actually been there.