Ottawa Weather in May
In May, Ottawa averages a high of 19°C (67°F) and a low of 8°C (46°F), from 55 years of daily records (1971–2026).
19°C
Average high
67°F
8°C
Average low
46°F
35°C
Record high
95°F · May 26, 2010
-3°C
Record low
27°F · May 1, 1978
What May Is Like in Ottawa
- The coldest May reading, -3°C (27°F) on May 1, 1978, has not been matched in 48 years.
- On average, 0.6 nights in May drop below freezing.
- May in Ottawa has become 0.6°C (1.0°F) warmer on average: the 2012–2026 average against 1970–1989.
- The warmest May in the record was 1998; the coldest was 1974.
At least 1 mm of rain falls on 32% of May days, and the month averages 77 mm in total.
Warmest: 1975 (23.7°C)Latest: 2026 (18.3°C)10-year averageLong-run average (19.2°C)
Look Up a Day in May
See the weather in Ottawa on any May date, year by year.
Source: NOAA GHCN-Daily, Ottawa Cda (1971–2023); Ottawa Cda Rcs (2000–2026). Averages cover 1971–2026. How we compute this