Belgium Brussels Weather in September — Climate Guide
September in Brussels is high
September is high for Brussels.
September is one of the best months to visit — still mild and often pleasant, but with summer's crowds and prices easing. It averages 20°C/11°C with 60mm of rain.
The Comic Strip Festival (Fête de la BD), usually in early-to-mid September, celebrates Belgium's comics heritage with events, parades, and a balloon's-day procession of giant inflatable characters — a fun, free-spirited weekend. Heritage Days open normally closed historic buildings to the public mid-month.
Travel score
Brussels September Weather Stats
Avg High
20°C
Avg Low
11°C
Rainy Days
13
60mm total
Sunshine
5h
Daily avg
Humidity
76%
comfortable
UV Index
4
Moderate
Wind
13 km/h
Gusts 26
Crowds
Busy
At attractions
September Sunrise & Sunset
Air Quality
PM2.5
16 μg/m³
PM10
26 μg/m³
Status
good
Feels-Like Temperature & Wind
Feels like
Daytime
20°C
Nighttime
11°C
Humidity and wind affect how the actual temperature feels.
Wind
13 km/h
Max gust 26 km/h
Activities Recommended for September
September Travel Pros & Cons
Pros
- Mild weather with easing crowds
- Comic Strip Festival (usually September)
- Heritage Days open historic buildings
- Better value than midsummer
Cons
- Cooler, fresher evenings
- Autumn rain returns late in the month
- Still some high-season pricing early on
- Days shortening
September Events & Festivals
- Comic Strip Festival (usually September) — murals, parades, balloons
- EU institutions back from recess
- Heritage Days (open historic buildings, mid-September)
- Shoulder season returns
Brussels in September — Full Picture
September is one of the best months to visit — still mild and often pleasant, but with summer's crowds and prices easing. It averages 20°C/11°C with 60mm of rain.
The Comic Strip Festival (Fête de la BD), usually in early-to-mid September, celebrates Belgium's comics heritage with events, parades, and a balloon's-day procession of giant inflatable characters — a fun, free-spirited weekend. Heritage Days open normally closed historic buildings to the public mid-month.
The weather is mild and the light is golden, ideal for walking the city and the day-trip towns with thinner crowds than midsummer. Café terraces stay busy on warm days.
The EU quarter returns to life after the summer recess, and the city's cultural season restarts. Prices soften from the July-August peak, making September strong value for the weather you get.
Note: autumn rain returns toward month's end, and evenings cool noticeably — bring a jacket and a rain layer.
What to Wear & What to Pack
Mild early autumn — around 20°C/11°C. Light clothing with a jacket or sweater for cooler evenings, plus a rain jacket. Pleasant by day, fresher after dark.
Packing Checklist
Seasonal Weather Overview
Spring (Mar·Apr·May)
14.3°C
5.7°C
15.3/mo
Summer (Jun·Jul·Aug)
22.3°C
13.3°C
13.3/mo
Autumn (Sep·Oct·Nov)
Current15°C
7.7°C
15/mo
Winter (Dec·Jan·Feb)
6.7°C
1.3°C
17.7/mo
Brussels Monthly Weather Comparison
| Month | High | Low | Rain | Sun | Humid | UV | Crowd | Price |
|---|---|---|---|---|---|---|---|---|
| 6° | 1° | 19d·75mm | 1.8h | 86% | 1 | Quiet | Low season | |
| 7° | 1° | 16d·65mm | 2.6h | 83% | 1 | Quiet | Low season | |
| 11° | 3° | 16d·65mm | 3.8h | 78% | 2 | Moderate | Shoulder | |
| 14° | 5° | 15d·55mm | 5.2h | 73% | 4 | Busy | Peak | |
| May (Best) | 18° | 9° | 15d·65mm | 6.2h | 71% | 5 | Busy | Peak |
| June (Best) | 21° | 12° | 14d·70mm | 6.6h | 70% | 6 | Busy | Peak |
| July (Best) | 23° | 14° | 13d·75mm | 7h | 71% | 6 | Very busy | Peak |
| August (Best) | 23° | 14° | 13d·75mm | 6.4h | 73% | 5 | Very busy | Peak |
| 20° | 11° | 13d·60mm | 5h | 76% | 4 | Busy | Shoulder | |
| 15° | 8° | 15d·75mm | 3.6h | 82% | 2 | Moderate | Shoulder | |
| 10° | 4° | 17d·75mm | 2h | 86% | 1 | Moderate | Shoulder | |
| 7° | 2° | 18d·80mm | 1.6h | 87% | 1 | Busy | Peak |
View Other Months
Brussels September Hotel Picks
Frequently Asked Questions
Is September a good time to visit Brussels?
Brussels in September is high. Tourist crowds are busy and flight/hotel prices are shoulder.
What's the average temperature in Brussels in September?
Brussels September averages a high of 20°C and a low of 11°C.
Does it rain much in Brussels in September?
Brussels September averages 60mm of rainfall over about 13 rainy days.
What should I wear in Brussels in September?
Mild early autumn — around 20°C/11°C. Light clothing with a jacket or sweater for cooler evenings, plus a rain jacket. Pleasant by day, fresher after dark.
What time are sunrise and sunset in Brussels in September?
Brussels September sunrise is 07:15 and sunset is 20:00, with 12h 45min of daylight.
What's the air quality like in Brussels in September?
Brussels September air quality (AQI) averages 42, rated Good. PM2.5 averages 16μg/m³.
What activities are recommended in Brussels in September?
In September, Brussels is great for Comic Strip Festival (usually September), Heritage Days (mid-September), Walking tours in mild weather.
Is September peak season in Brussels?
Brussels September crowds are busy and prices are shoulder. Advance reservations are strongly recommended.
Best Months to Visit Brussels
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.