Swimming in Derry (Londonderry) in september 2025: Average sea temperature in september and tide times in september 2025
Average sea temperature in Derry (Londonderry) in september 2025.
In september, according to seasonal norms, the sea temperature in Derry (Londonderry) is:
Minimum: 57°F
Average: 58°F
Maximum: 60°F
Other useful seasonal weather averages in september:
- Outside temperature: 50°F to 60°F
- Most common weather: "Cloudy"
- The wind blows at 5mph
- It rains a total of 1.7in, over 1 day(s).
Should we swim in Derry (Londonderry) in september?
No... The water temperature in Derry (Londonderry) in september is freezing
You won't be able to swim in Derry (Londonderry) in september! The water temperature is freezing, reaching as low as 57°F (and only 60°F at best)! Our advice: if you are going to Derry (Londonderry) this month, plan to sightsee and forget the beach!
Note also that in september, the climate is tolerable with an average outside temperature of 55°F, 1.7in of precipitation (over 1 days) and 94.32 % humidity.
Water and normal seasonal temperatures in Derry (Londonderry) in september
| September | |||
| Average sea temperature | 58°F | ||
| Minimum sea temperature | 57°F | ||
| Maximum sea temperature | 60°F | ||
| Average outside temperature | 56°F | ||
| Maximum outside temperature | 61°F | ||
| Minimum outside temperature | 50°F | ||
| Wind speed | 12.4mph | ||
| Wind temperature | 47°F | ||
| Precipitation | 1.7in | ||
| Number of days of rain | 1 jour(s) (5%) | ||
| Humidity | 95% | ||
| Visibility in kilometers | 8.04km | ||
| Cloud cover | 65% | ||
| Our opinion | freezing swimming |
Chart of the tides in september 2025
Tide times in september 2025 in Derry (Londonderry)
Swim elsewhere in Northern Ireland in september
| City | Average T° | Min. T° | Max. T° | Our opinion | Belfast in september | 58°F | 59°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