London weather in September
Long-run climate averages for London, Ontario in September, plus what the forecast models say for the days ahead.
In September, London averages 21°C by day and 12°C at night. The wettest month is usually November.
September in London averages a daytime high of 21°C and an overnight low of 12°C, which reads as mild for this part of the world. Across the whole year London sees roughly 1001 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 London forecast with every model compared and how much they currently agree.
London weather by month
what to expect in London through the year, 1991-2020 averagesHere is London'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 London by season.
Bottom line: over the last 30 days the European model has been the most accurate forecast for London, scoring 94/100 on our CheckWeather Score, ahead of the American at 89. See the full CA accuracy scoreboard for exactly how every model is tested.
Common questions
How warm is London in September?
Is September a good time to visit London?
Does it rain a lot in London in September?
Climate averages from ERA5 reanalysis. Model accuracy re-scored over a rolling 30 days. Page updated .