Brussels Weather by Month: Temperatures, Rain, Sun and When to Go

The short answer. May, June and September are the months to aim for. Roam Brussels read 13 guides on when to go, and 12 name late spring, 9 name September or October and 5 call July and August the warm window. The weather figures show why the first two hold up. May to June has 198 to 199 hours of sun a month and September still has 154, with 14 to 15 rainy days in each. July, at a 23.2°C (73.8°F) average high, is the warmest month. January is the coldest at a 6.1°C (43.0°F) high and a 1.4°C (34.5°F) low, and December is the wettest at 87.4 mm over 19.4 days.

Roam Brussels is a data platform as well as a guide, so the numbers below come from the national weather institute and the picks come from the guides. The picks are ordered by how many guides name them.

The short list

Brussels weather by month

The figures are the 1991 to 2020 normals that the Royal Meteorological Institute of Belgium publishes for Uccle, one of the southern communes of the region. They’re the temperature, precipitation and sunshine duration pages of the institute’s normals for Uccle, and the pages explain that a normal is a 30-year average. A rainy day there is a day with at least 0.1 mm of precipitation, which isn’t a high bar, so the day counts look high next to counts that need 1 mm. The Fahrenheit figures are converted from the institute’s Celsius values.

Rain falls in every month, and you’ll want a waterproof layer whatever the date. Seven of the 13 guides say the same, and the table backs them up, since no month has fewer than 13 rainy days. The wettest months are December and August, and the driest is April.

May and June

Recommended by 12 of 13 guides read.

May has an 18.4°C (65.1°F) high and a 9.2°C (48.6°F) low, with 59.7 mm of rain. June reaches 21.2°C (70.2°F) with 70.8 mm. Both months average close to 200 hours of sun, which is more than three times January’s. The guides that name spring mean the stretch from late April to June, and they give the same reasons. Terraces reopen, the parks are green and the crowds and hotel rates sit below the July and August peak. One adds that May draws more visitors as the month goes on. A few point to the longer evenings, which let you fit a full day on foot into the Cinquantenaire Park and Brussels Park side of the city, then sit outside after. The May events page and the June events page list what’s on.

September and October

Recommended by 9 of 13 guides read, September for the weather and October more for the colour.

September averages 19.5°C (67.1°F) by day and 11.3°C (52.3°F) at night, with 65.3 mm of rain and 154 hours of sun, so it’s still warm and it has as few rainy days as June. One guide calls it the smartest month to visit, because the summer crowds have thinned and hotels return to ordinary rates. October drops to a 14.9°C (58.8°F) high with 16.1 rainy days and 113 hours of sun. A guide that rates the first half of October as pleasant and the second half as wetter is in line with those numbers, since the rain doesn’t ease before November. The wooded edges of the city are the draw, namely the Forêt de Soignes, the Bois de la Cambre and the Étangs d’Ixelles. See the September events page, and the events calendar once October’s programme is out.

July and August

Named as the warm window by 5 of 13 guides read, and called busy and pricier by 7.

July has a 23.2°C (73.8°F) average high and the most sun of the year at 203 hours. August is almost as warm at 23.0°C (73.4°F), but it has 86.5 mm of rain, the second most of any month after December. The guides that favour these months score on sun and warmth. The ones that weigh crowds describe the busiest weeks and higher hotel prices. Highs in the low twenties mean the city doesn’t get as hot as southern Europe, and it’s worth knowing that one guide notes the nights can fall below 10°C even in July or August, so carry a light jacket. Look at the July events page and the August events page. For a hot afternoon the Atomium and the Mini-Europe park next to it are an easy half day.

April and March

April is named by 5 of 13 guides read, usually as the start of spring. March is a less common pick.

April is the driest month in the normals, with 46.7 mm and 13.1 rainy days, and it reaches 15.0°C (59.0°F) by day with a 6.0°C (42.8°F) low. That’s why the guides that start the good season in April, rather than May, sound sure of it. The first week or two can still be cold, so you’ll want a coat. March averages a 10.9°C (51.6°F) high and a 3.5°C (38.3°F) low, with 2.7 snow days, and the guides that cover it call it a quiet month before the season. The March events page and the April events page list what’s on.

Winter: the cheap, quiet season, and the Christmas market

December for the Christmas market is named by 7 of 13 guides read, and January and February as cheap and quiet by 6.

December averages 6.6°C (43.9°F) by day and 2.1°C (35.8°F) at night, with 87.4 mm of rain over 19.4 days and 49 hours of sun for the whole month. January has 59 hours and February 73. Snow falls on 3.8 days in January, 4.9 in February and 3.7 in December, so it’s there often enough to notice but the guides say it doesn’t lie for long. Seven guides point to the Christmas market. The organiser’s page lists Plaisirs d’Hiver (Winter Wonders) from 27 November 2026 to 3 January 2027, and the market has its own entry on the map. Six guides call January and February the cheapest and quietest weeks, with short museum queues. Two guides tell you to skip winter, one for the rain and short days and one unless you’re going for the market. For a wet day the Comics Art Museum and the Musical Instruments Museum are the kind of stops the museum-minded guides suggest. November is the month several guides rate weakest, at 9.9°C (49.8°F) with 18.3 rainy days and 66 hours of sun, and it lacks the low prices of January nor the market. The November events page, the December events page, the January events page and the February events page list what’s on.

Which month has the best weather?

June, on the numbers. It has a 21.2°C (70.2°F) high, 14.1 rainy days and 199 hours of sun, and it’s before the July and August crowds. September comes next, with the same 14.1 rainy days and a 19.5°C (67.1°F) high. April is the driest month but still cool, and July is the sunniest but busier. That matches the guides, and they put May, June and September ahead of the rest.

Planning around the weather

• Use the map to find indoor places for a wet day, and events and live music for what is on the dates you travel.
• Plan for showers in any month. A compact umbrella and a layer you can add or drop will serve you better than trusting one forecast.
• If a trip falls in the cold months, put the long outdoor walks in the middle of the day. The sun shines for only 49 hours in all of December.

Places in this guide

Photos show the actual places, licensed under Creative Commons and credited to their photographers.

Brussels Park Mont des Arts and Royal Quarter Photo: Miguel Discart & Kiri Karma Étangs d'Ixelles Matongé and Flagey Photo: Stephane Mignon Mini-Europe Laeken and Heysel Photo: Tom Parnell