Knokke-Heist weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Poor
Best time to visit: July – August
What is the weather like in Knokke-Heist in September?
In September, Knokke-Heist is mild: daytime highs average 19 °C, and nights cool down to about 13 °C. The sea averages 17.9 °C – bracing, so a wetsuit helps for longer swims. Expect around 6 hours of sunshine a day. Rain is frequent, with about 10 rainy days and 61 mm in total. All in all, September is not an ideal month for a holiday in Knokke-Heist.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 44 | 23 | 9 |
| Day | 21° | 19° | 15° |
| Night | 16° | 13° | 10° |
| Sea | 19° | 18° | 15° |
| Sun | 7 h | 6 h | 4 h |
| Rain days | 12 | 10 | 14 |
More details for September
- Daylight
- 12 h 44 min07:20 – 20:04
- UV index
- 4 · moderateclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 22 km/haverage daily peakAll months
- Cloud cover
- 62 %on averageAll months
- Hot days
- 0 days30 °C or more
- Snow days
- 0 days1 cm or more of fresh snow
- Time zone
- UTC+2Europe/Brussels
How the score comes together
- Temperatureweight 35 %0 %
- Seaweight 25 %13 %
- Sunshineweight 20 %43 %
- Few rainy daysweight 20 %56 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in September
- Wetsuit for longer swims
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
Knokke-Heist in September: quick answers
Is Knokke-Heist hot in September?
No. In September, Knokke-Heist is mild: daytime highs average 19 °C and nights drop to about 13 °C.
Can you swim in Knokke-Heist in September?
Only if you don't mind cold water: in September the sea averages just 17.9 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Knokke-Heist in September?
Rain is frequent, with about 10 rainy days and 61 mm in total.
Knokke-Heist month by month
The whole year in Knokke-HeistAll destinations: BelgiumWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences