Normal weather for Ontario in September
It's warm in September in Ontario with an average temperature of 23°C. Temperatures this month range from a low of 18°C to a high of 26°C. At night, you can expect temperatures between 12°C and 18°C.
In September, there is an average of 58 mm of precipitation, spread over 8 days. The wind speed is around 4 Bft, mostly coming from the South.
Ontario in September |
New York | ||
|---|---|---|---|
 Average Temperature |
23°C | 27°C | |
 High Temp |
26°C | 31°C | |
| Low Temp |
18°C | 21°C | |
 Total Precipitation |
58 mm | 57 mm | |
| Rainy Days |
8 days | 9 days | |
Start of September
The month of September starts in Ontario with warm temps, averaging around 25°C during the day and nights around 18°C. A few showers might pop up early in the month, but overall, it’ll stay mostly sunny and dry.
With the temperature difference between day and night, it’s smart to wear layers. A T-shirt, light pants or skirt, and a light jacket are great for the day. For the evening and morning, a shirt, maybe a light sweater, and thin pants are recommended.
Mid September
By mid-September, daytime temps drop to around 23°C, with nights around 15°C. Not much precipitation expected during this period. It’s mostly dry and sunny.
Since it cools down at night, it’s a good idea to wear layers. A T-shirt, light pants or skirt, and a light jacket are great for the day. In the evening and morning, choose a light jacket, sweater or hoodie, and long pants.
End of September
By the end of September, the average daytime temperature in Ontario is around 22°C, while nighttime temps are about 14°C. A shower might pop up, but overall, the weather will be dry and sunny.
Because temperatures drop in the evening, wearing layers is recommended. A T-shirt, light pants or skirt, and a light jacket are great for the day. In the evening and morning, choose a light jacket, sweater or hoodie, and long pants.
Find affordable vacations to Ontario 
UV index
The UV index is a maximum of 7 this month. That's a moderate to high value on the intensity scale of 1 to 11. Unprotected skin can burn within 15-25 minutes.
Is September a good time to visit Ontario?
Looking for great weather? September is a good time to be in Ontario. The temperatures are nice, and there’s not too much rain.
Temperature records for Ontario in September
Check out the climate of Ontario for all months and discover the best travel time
Curious about the weather in other parts of Canada? Check out the climate and weather for spots like Vancouver, Toronto, Niagara Falls, or explore other destinations in Canada.
August
Plan your next vacation
Don’t miss the best vacation deals for Ontario and see what our partners have for you.
Daily Temperature in September in Ontario
This chart shows the average daily high and low temperatures in September for Ontario, in degrees Celsius. The red line represents the highs, and the blue line shows the lows. The days of the month are displayed at the bottom of the chart. The data, based on historical observations, provide the average temperatures for this month.
Daily Precipitation in September in Ontario
The chart below shows the average daily precipitation in September for Ontario, measured in millimeters over the past few years. Precipitation is always measured as water, even if it’s snow or hail. The days of the month are listed at the bottom of the chart.
A low average precipitation means that the chance of rain on that day is usually small, while a higher average suggests that it rained more often. But remember, it’s just an average, and every day can be different. Based on historical weather data for September, you can expect about 8 days of precipitation in Ontario.
Daily UV Index in September in Ontario
This chart shows the average daily UV index in September in Ontario, with the UV index ranging from 0 to a maximum of 11. The bottom of the chart shows the days of the month. Based on historical data, this chart provides an idea of the daily UV radiation levels you can expect.
Temperature in September in Ontario Over the Years
This chart shows the average temperature in September in Ontario, measured in degrees Celsius, over the past few years.
Total Precipitation in September in Ontario Over the Years
This chart shows the average precipitation in September in Ontario, measured in millimeters over the past years. Precipitation is always measured as water, whether it’s snow or hail.
Daily Climate in September for Ontario
Click on any day in September to get detailed info about the usual weather on that day in Ontario. Check out the historical temperatures and precipitation over the past 10 years on this day.
Weather experiences in September in Ontario
Have you been to Ontario in September?
Share your weather experience in September in Ontario.
Average Weather in Ontario by Month
Click on a month below to see detailed weather info for Ontario. Based on historical weather data, you can see the average temperature, precipitation, wind, and UV index for each day of the month.
