Belfast weather in September
Long-run climate averages for Belfast, Northern Ireland in September, plus what the forecast models say for the days ahead.
In September, Belfast averages 17°C by day and 10°C at night. The wettest month is usually July.
September in Belfast averages a daytime high of 17°C and an overnight low of 10°C, which reads as mild for this part of the world. Across the whole year Belfast sees roughly 1125 mm of precipitation.
Climate averages tell you what to pack. They do not tell you what next Tuesday looks like — for that, see the live Belfast forecast with every model compared and how much they currently agree.
Belfast weather by month
what to expect in Belfast through the yearHere is Belfast's typical weather in each month: the average daytime high and overnight low in °C, how each month feels, and the wettest month marked. Use it to plan any trip to Belfast by season.