If you plan to visit Ottawa in September, the weather is typically alright, with an average high temperature of +70°F during the day and approximately 4 sunny days. Expect some rainy, though, as there are typically 12 rainy days in the month and around 88 mm of precipitation. The weather is changeable so you may have to pack for every eventuality. Search flightsin one click on Avionero.
Average weather
☀️
+70°F
Avg. max. temperature
+27°F
Min.
+95°F
Max.
88 mm
Total precipitation
75%
Avg. humidity
2 m/s
Avg. wind
4 ☀️
Sunny Days
12 ⛅️
Cloudy
12 🌦
Rainy
Our opinion: Ottawa has OK weather in September.
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Average temperature in Ottawa in September
Here are the expected maximum, average and minimum temperatures in Ottawa for September based on the historical data.
Last Year
Historical Data
Going from a maximum of +91°F during the day to a minimum of +45°F during the night, the temperature in September averages around +73°F.
The average maximum temperature goes up 4% by the end of the month, compared with the beginning of the month, from +75°F to +77°F.
Is Ottawa warm or cold in September?
Ottawa is typically mild in September.
Maximum temperatures go down compared to the previous month from +77°F to +70°F. The minimum temperature also goes down from +59°F to +52°F.
Pack a light jacket as it will be warm in the day and cool in the evenings.
Take a look at how September is compared to other months in Ottawa:
Climate in Ottawa in September
Ottawa weather looks like this, on average, in September and the surrounding months.
August
September
October
Avg. temperature
+77°F
+70°F
+55°F
Min. temperature
+39°F
+27°F
+18°F
Max. temperature
+97°F
+95°F
+86°F
Rainfall
85 mm
88 mm
90 mm
Wind
2 m/s
2 m/s
3 m/s
Humidity
72%
75%
76%
Air pressure
1014 HPa
1016 HPa
1015 HPa
Sunny days
4
4
3
Cloudy days
11
12
12
Rainy days
12
12
14
Snowy days
0
0
1
September typically has worse weather conditions compared to August.It’s getting colder in September. From +77°F in the day, the average maximum temperature lowers to +70°F.Prepare for more rain. Average rainfall goes from 85 mm to 88 mm.Humidity rises from 72% to 75%.The average wind speed doesn’t change much during September, staying around 2 m/s.The amount of sunny days stay about the same, averaging 4 sunny days during the month.
October brings much the same weather, it remains ok.
Wind speed in Ottawa in September based on historical data.
Last Year
Historical Data
The average wind speed is 3 m/s getting up to 5 m/s which is a light breeze; barely moving the tree leaves.
The average wind speed in Ottawa is gradually increasing during September, going from 2 m/s to 2 m/s over the course of the month.
Rain
Amount of rainfall in mm during September in Ottawa based on historical data.
Last Year
Historical Data
Typically, there is a 17% chance of rain on an average day in September, with total rainfall of approximately 29 mm. The maximum amount of rainfall per day is around 21 mm, which is considered light rain.On average, there are about 5 rainy days during September, so prepare to bring an umbrella.
Here’s how September is compared with other months in the amount of precipitation, total mm:
Ottawa wettest month is July, where a typical day has a 35% chance of precipitation and 91 mm of rainfall per day. February, on the other hand, is the driest month with a mere 3% chance of precipitation and 12 mm of rainfall per day.
How was the weather last September in Ottawa?
This is the weather in Ottawa in September 2023:
1 September
☀️
+76°F
2 September
☁️
+77°F
3 September
☀️
+85°F
4 September
☁️
+87°F
5 September
☀️
+91°F
6 September
☀️
+90°F
7 September
☁️
+84°F
8 September
☁️
+77°F
9 September
☁️
+74°F
10 September
☁️
+72°F
11 September
☀️
+76°F
12 September
☁️
+69°F
13 September
☁️
+70°F
14 September
☁️
+63°F
15 September
☀️
+72°F
16 September
☁️
+73°F
17 September
☁️
+74°F
18 September
☁️
+70°F
19 September
🌧️
+66°F
20 September
☀️
+65°F
21 September
☀️
+70°F
22 September
☀️
+74°F
23 September
☁️
+71°F
24 September
☁️
+76°F
25 September
🌫️
+71°F
26 September
☁️
+66°F
27 September
☁️
+67°F
28 September
☁️
+71°F
29 September
☁️
+71°F
30 September
☁️
+76°F
In September 2023 Ottawa had 9 sunny days, 19 cloudy days, and 1 rainy days. The average maximum temperature was +73°F, with an absolute maximum of +91°F and a minimum of +63°F. The average humidity was 79%, with a maximum of 100% and a minimum of 39%. The average wind speed was 3 m/s, with a maximum of 8 m/s and a minimum of 0 m/s.
Are you planning a trip in September?
Climate Change Over the Years
This is how Ottawa climate has changed over the last 43 years.
The climate in Ottawa in September has not changed that much over the last 43 years.
The average temperature was the lowest in 1992 (+51°F) and the highest in 2012 (+56°F). The driest year was 1985 with only 469 mm of rainfall, and the wettest year was 2017 with 1378 mm.
FAQ
Frequently asked questions about the weather in Ottawa in September:
Is September a good time to visit Ottawa?
It’s always a good time to visit Ottawa, but the weather is changeable in September, so plan a mix of indoor and outdoor activities and exploring, and pack for every eventuality.
Can you sunbathe in Ottawa in September?
September has mild temperatures in Ottawa. Not ideal for sunbathing, but still good for daytime outdoor activities, but plan for cool evenings. Pack a light jacket and shorts!
Is Ottawa rainy in September?
Ottawa is often rainy in September. You may get a bit damp when outside, so pack an umbrella, and maybe even a raincoat.
Is it sunny in Ottawa in September?
Usually, it’s not very sunny in Ottawa in September, often it’s pretty cloudy. Pack for any eventuality; layering can help reduce the number of bulky items needed.
For this page, we’ve looked at the typical weather in Ottawa, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.
