Weathermondo.com
United StatesThe weather in September in Ottawa
It's warm in September in Ottawa with an average temperature of 26°C. Temperatures this month range from a low of 22°C to a high of 29°C. At night, you can expect temperatures between 10°C and 17°C.
Looking for great weather? September is a good time to be in Ottawa. The temperatures are nice, and there’s not too much rain.
Average temperatures and precipitation
This chart shows the average daily maximum and minimum temperatures (in degrees Celsius) and precipitation (in millimeters) in September for Ottawa, Illinois. A low precipitation value usually indicates little to no rainfall on that day in recent years, while a higher value suggests more frequent rainfall.
Temperature records
With 36°C in 2018, Ottawa reached the highest temperature in September over the past 10 years. The lowest daytime temperature in this month was 13°C in 2014. The extreme nighttime temperatures ranged from a lowest recorded value of 3°C to a highest value of 24°C.
Rainfall amount
In September, there is an average of 65 mm of precipitation, spread over 10 days. The wind speed is around 3 Bft, mostly coming from the South.
Daily weather in September for Ottawa
Click on any day in September to get detailed info about the usual weather on that day in Ottawa. Check out the historical temperatures and precipitation over the past 10 years on this day.
September weather comparison
| Ottawa | New York | |
|---|---|---|
| Average temperature | 26°C | 27°C |
| Max. temperature | 29°C | 31°C |
| Min. temperature | 10°C | -5°C |
| Total precipitation | 65 mm | 57 mm |
| Rainy days | 10 days | 9 days |
Start of September
The month of September starts in Ottawa with hot temps, averaging around 27°C during the day and nights around 17°C.
Mid September
By mid-September, daytime temps stay steady at around 27°C, with nights around 15°C. There’s a chance of some showers during this time, but plenty of dry and sunny days too.
End of September
By the end of September, the average daytime temperature in Ottawa is around 25°C, while nighttime temps are about 14°C. A shower might pop up, but overall, the weather will be dry and sunny.
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UV index
The UV index is a maximum of 8 this month. That's a very high value on the intensity scale of 1 to 11. Unprotected skin can burn within 10-15 minutes.
Check out the climate of Ottawa for all months and discover the best travel time
Temperature charts
These charts show the average temperatures in September in Ottawa, Illinois. The temperatures are shown in degrees Celsius and are calculated based on data from the past 10 years.
Daily Temperature in September in Ottawa
Temperature in September in Ottawa over the years
Precipitation charts
These charts show the average amount of precipitation in September in Ottawa, Illinois. Precipitation is always measured as water, even when it falls as snow or hail The amount of precipitation is displayed in millimeters, while snowfall is shown in centimeters.
Daily Precipitation in September in Ottawa
Total precipitation in September in Ottawa over the years
Daily UV index in September in Ottawa
This chart shows the average daily UV index in September in Ottawa, 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.
Weather experiences in September in Ottawa
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Average weather in Ottawa by month
Click on a month below to see detailed weather info for Ottawa. Based on historical weather data, you can see the average temperature, precipitation, wind, and UV index for each day of the month.