Ottawa is warmest in July, averaging 27° by day and 15° at night. The wettest month is August with 112 mm, and the year brings about 905 mm in total.
Month by month
| Month | High | Low | Rain | Daylight | Good for |
|---|---|---|---|---|---|
| January | -6° | -17° | 62 mm | 8.9 h | Cool |
| February | -4° | -16° | 50 mm | 10.1 h | Cool |
| March | 4° | -9° | 62 mm | 11.6 h | Cool |
| April | 12° | -1° | 78 mm | 13.3 h | Cool |
| May | 19° | 7° | 62 mm | 14.7 h | Sightseeing |
| June | 24° | 12° | 99 mm | 15.5 h | Sightseeing |
| July | 27° | 15° | 105 mm | 15.1 h | Beach weather |
| August | 26° | 15° | 112 mm | 13.9 h | Mild |
| September | 22° | 10° | 63 mm | 12.3 h | Sightseeing |
| October | 15° | 4° | 74 mm | 10.7 h | Mild |
| November | 6° | -3° | 57 mm | 9.3 h | Cool |
| December | -1° | -11° | 81 mm | 8.5 h | Cool |
High and low are average daily maximum and minimum, rain is typical monthly total, daylight is the hours between sunrise and sunset mid-month. Climate normals from NASA POWER — averages, not promises.
When to go
Beach weather: July — highs around 27°, nights no colder than 15°, and at most 105 mm of rain in a month.
Walking the city: May, June and September — highs of 19–24° and no more than 99 mm of rain a month.