Markham Weather in September
What's the weather like in Markham (Ontario) in September 2025?
The climate in Markham during September can be summarized as mild and reasonably dry.
September is in the fall / autumn in Markham and is typically the 4th warmest month of the year. Daytime maximum temperatures average around 20°C (68°F), whilst at night 10°C (49°F) is normal.
| Daytime temperature | 20.1°C 68.2°F |
|---|---|
| Nightly temperature | 9.5°C 49.1°F |
| Average temperature | 14.8°C 58.6°F |
| Daily sunshine | 6.3 hrs |
| Avg rainfall | 72 mm 2.8 ins |
| Rainy days | 9 days |
| Sea temperature | 19.1°C 66.4°F |
| Humidity | 77% |
| Windspeed | 13kph 8 mph |
On average September is the 6th wettest month of the year in Markham with around 72mm 2.8 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 9 days, although this may vary considerably.
On the flip side this corresponds to an average of 6.3 hours of sunshine per day.
September temperatures in Markham
September rainfall
September hourly sunshine
The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Markham in September 2025.
Other monthly averages
Best places to visit in September
Markham weather stats
| Hottest month: | July | 25.9°C 78.6°F |
|---|---|---|
| Driest month: | February | 49mm 1.9ins |
| Sunniest month: | July | 9.8hrs |
| Coldest month: | January | -3.7°C 25.3°F |
| Wettest month: | August | 89mm 3.5ins |
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