Swimming in Belfast in september 2025: Average sea temperature in september and tide times in september 2025
Average sea temperature in Belfast in september 2025.
In september, according to seasonal norms, the sea temperature in Belfast is:
Minimum: 57°F
Average: 58°F
Maximum: 59°F
Other useful seasonal weather averages in september:
- Outside temperature: 51°F to 60°F
- Most common weather: "Cloudy"
- The wind blows at 5.6mph
- It rains a total of 3.9in, over 6 day(s).
Should we swim in Belfast in september?
No... The water temperature in Belfast in september is freezing
You won't be able to swim in Belfast in september! The water temperature is freezing, reaching as low as 57°F (and only 59°F at best)! Our advice: if you are going to Belfast this month, plan to sightsee and forget the beach!
Note also that in september, the climate is tolerable with an average outside temperature of 56°F, 3.9in of precipitation (over 6 days) and 92.51 % humidity.
Water and normal seasonal temperatures in Belfast in september
| September | |||
| Average sea temperature | 58°F | ||
| Minimum sea temperature | 57°F | ||
| Maximum sea temperature | 59°F | ||
| Average outside temperature | 58°F | ||
| Maximum outside temperature | 61°F | ||
| Minimum outside temperature | 52°F | ||
| Wind speed | 13.1mph | ||
| Wind temperature | 49°F | ||
| Precipitation | 3.9in | ||
| Number of days of rain | 6 jour(s) (20%) | ||
| Humidity | 93% | ||
| Visibility in kilometers | 8.72km | ||
| Cloud cover | 57% | ||
| Our opinion | freezing swimming |
Chart of the tides in september 2025
Tide times in september 2025 in Belfast
Swim elsewhere in Northern Ireland in september
| City | Average T° | Min. T° | Max. T° | Our opinion | Derry (Londonderry) in september | 58°F | 60°F | freezing swimming | Portrush in september | 58°F | 60°F | freezing swimming | Portstewart in september | 58°F | 59°F | freezing swimming |
Swim in Northern Ireland in september: sea temperature by city