Ottawa
Canada
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Ottawa, Canada

A view of The Parliament Hill from the Ottawa River in Ottawa, Canada
A view of The Parliament Hill from the Ottawa River in Ottawa, Canada
September, the first month of the autumn, in Ottawa, is also an agreeable month, with average temperature ranging between min 9.6°C (49.3°F) and max 20.4°C (68.7°F).

Temperature

In Ottawa, Canada, the average high-temperature in September slightly decreases, from a warm 25.3°C (77.5°F) in August, to an agreeable 20.4°C (68.7°F). In September, in Ottawa, Canada, the average low-temperature is 9.6°C (49.3°F).

Humidity

In September, the average relative humidity is 59.1%.

Rainfall

In Ottawa, it is raining for 12.3 days, with typically 90.1mm (3.5") of accumulated precipitation. Throughout the year, there are 118.4 rainfall days, and 758.4mm (29.9") of precipitation is accumulated.

Snowfall

In Ottawa snow does not fall in June through September.

Daylight

In Ottawa, Canada, the average length of the day in September is 12.5h.

Sunshine

In September, the average sunshine in Ottawa, Canada, is 7.1h.

UV index

In Ottawa, Canada, the average daily maximum UV index is 5. A UV Index value of 3 to 5 symbolizes a medium vulnerability from the exposure to the Sun's UV rays for average individuals.
Note: In September, the average maximum UV index of 5 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.

What is the temperature in September in Ottawa?

In September, the average high-temperature is 20.4°C (68.7°F), and the average low-temperature is 9.6°C (49.3°F).

What is the average humidity in September in Ottawa?

The average relative humidity in September in Ottawa is 59.1%.

How much does it rain in Ottawa in September?

In September, the rain falls for 12.3 days. Throughout September, 90.1mm (3.5") of precipitation is accumulated.

Does it snow in Ottawa in September?

In Ottawa, in September, it doesn't snow. In October, it regularly snows.

When it does not snow in Ottawa?

June through September are months without snowfall in Ottawa.

What is the average length of the day in September in Ottawa?

In September, the average length of the day in Ottawa, Canada, is 12.5h.

How many hours of sunshine does Ottawa have in September?

In September, the average sunshine in Ottawa is 7.1h.

What is the UV index intensity in September in Ottawa?

In September, the average daily maximum UV index in Ottawa, Canada, is 5. A UV Index of 3 to 5 symbolizes a moderate health threat from unsafe exposure to the Sun's UV rays.
Average temperature in September - Ottawa, Canada
  • Average high temperature in September: 20.4°C

The warmest month (with the highest average high temperature) is July (26.5°C).
The month with the lowest average high temperature is January (-5.8°C).

  • Average low temperature in September: 9.6°C

The month with the highest average low temperature is July (15.5°C).
The coldest month (with the lowest average low temperature) is January (-14.8°C).

Average humidity in September - Ottawa, Canada
  • Average humidity in September: 59.1%

The month with the highest relative humidity is December (72.2%).
The month with the lowest relative humidity is May (49.9%).

Average rainfall in September - Ottawa, Canada
  • Average rainfall in September: 90.1mm

The wettest month (with the highest rainfall) is June (92.8mm).
The driest month (with the lowest rainfall) is February (18.7mm).

Average rainfall days in September - Ottawa, Canada
  • Average rainfall days in September: 12.3 days

The month with the highest number of rainy days is October (13.7 days).
The month with the lowest number of rainy days is February (3.9 days).

Average snowfall in September - Ottawa, Canada
  • Average snowfall in September: 0mm

The month with the highest snowfall is January (539mm).
Months with the lowest snowfall are June, July, August and September (0mm).

Average snowfall days in September - Ottawa, Canada
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (16.1 days).
Months with the lowest number of snowfall days are June, July, August and September (0 days).

Average daylight in September / Average sunshine in September - Ottawa, Canada
  • Average daylight in September: 12.5h

The month with the longest days is June (Average daylight: 15.6h).
The month with shortest days is December (Average daylight: 8.8h).

  • Average sunshine in September: 7.1h

The month with most sunshine is July (Average sunshine: 9.7h).
The month with least sunshine is December (Average sunshine: 2.2h).

Average UV index in September - Ottawa, Canada
  • Average UV index in September: 5

The month with the highest UV index is June (UV index 8).
Months with the lowest UV index are January, November and December (UV index 1).