Weather on September 18 in Ottawa
Historical weather data for September 18 in Ottawa, Canada
Based on 55 years of data from OTTAWA CDA
About This Date
September 18th in Ottawa, Canada typically brings mild fall weather, with average highs around 21°C and lows near 9°C. Over 55 years of records, the warmest September 18th was in 1992 (22°C average), while the coldest was 1974 (8°C) — a 25°F range across recorded history. Rain or other precipitation has occurred on about 31% of September 18th dates historically, with the wettest September 18th recording 3.79" of rain. The last decade has been 2.8°F warmer on this date compared to 20-30 years ago.
The last decade has been 2.8°F warmer on this date compared to 20-30 years ago.
Planning for September 18th in Ottawa? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Year by Year History
| Year | High | Low | Precip |
|---|---|---|---|
| 2025 | 26°C (78°F) | 12°C (54°F) | -- |
| 2024 | 29°C (84°F) | 13°C (55°F) | 0" |
| 2023 | 21°C (70°F) | 13°C (56°F) | 3.79" |
| 2022 | 22°C (71°F) | 13°C (55°F) | 1.74" |
| 2021 | 22°C (72°F) | 11°C (52°F) | 0" |
| 2020 | 13°C (56°F) | 3°C (37°F) | 0" |
| 2019 | 21°C (69°F) | 9°C (48°F) | 0" |
| 2018 | 23°C (74°F) | 16°C (61°F) | 0" |
| 2017 | 28°C (82°F) | 13°C (55°F) | 0" |
| 2016 | 26°C (79°F) | 17°C (62°F) | 0" |
| 2015 | 28°C (83°F) | 16°C (60°F) | 0" |
| 2014 | 12°C (53°F) | 5°C (41°F) | 0" |
| 2013 | 22°C (71°F) | 4°C (39°F) | 0" |
| 2012 | 19°C (66°F) | 14°C (58°F) | 2.73" |
| 2011 | 19°C (67°F) | 3°C (37°F) | 0" |
| 2010 | 19°C (67°F) | 4°C (40°F) | 0" |
| 2009 | 17°C (62°F) | 7°C (45°F) | 0.06" |
| 2008 | 13°C (56°F) | 6°C (43°F) | 0" |
| 2007 | 22°C (72°F) | 5°C (41°F) | 0" |
| 2006 | 27°C (80°F) | 13°C (56°F) | 0.63" |
| 2005 | 24°C (75°F) | 15°C (59°F) | 0.02" |
| 2004 | 15°C (59°F) | 8°C (46°F) | 0" |
| 2003 | 24°C (76°F) | 8°C (47°F) | 0.08" |
| 2002 | 23°C (74°F) | 9°C (49°F) | 0" |
| 2001 | 19°C (67°F) | 14°C (57°F) | 0" |
| 2000 | 21°C (70°F) | 7°C (45°F) | 0" |
| 1999 | 22°C (72°F) | 8°C (47°F) | 0" |
| 1998 | 23°C (73°F) | 8°C (47°F) | 0" |
| 1997 | 24°C (75°F) | 13°C (55°F) | 0.02" |
| 1996 | 23°C (73°F) | 11°C (52°F) | 0" |
| 1995 | 15°C (59°F) | 4°C (40°F) | 0" |
| 1994 | 17°C (62°F) | 8°C (46°F) | 0.05" |
| 1993 | 18°C (64°F) | 13°C (55°F) | 0" |
| 1992 | 27°C (80°F) | 18°C (64°F) | 2.12" |
| 1991 | 23°C (74°F) | 9°C (48°F) | 0.02" |
| 1990 | 15°C (59°F) | 3°C (37°F) | 0" |
| 1989 | 24°C (75°F) | 8°C (46°F) | 0" |
| 1988 | 22°C (72°F) | 13°C (55°F) | 0" |
| 1987 | 18°C (65°F) | 8°C (46°F) | 0" |
| 1986 | 18°C (64°F) | 6°C (42°F) | 0" |
| 1985 | 28°C (82°F) | 7°C (44°F) | 0" |
| 1984 | 22°C (71°F) | 6°C (43°F) | 0" |
| 1983 | 19°C (67°F) | 13°C (55°F) | 0" |
| 1982 | 18°C (64°F) | 9°C (48°F) | 0.12" |
| 1981 | 17°C (62°F) | 11°C (51°F) | 0" |
| 1980 | 14°C (58°F) | 4°C (39°F) | 0" |
| 1979 | 24°C (75°F) | 13°C (55°F) | 1.2" |
| 1978 | 13°C (55°F) | 3°C (38°F) | 0.16" |
| 1977 | 21°C (69°F) | 16°C (60°F) | 0" |
| 1976 | 20°C (68°F) | 18°C (64°F) | 1.42" |
| 1975 | 18°C (64°F) | 11°C (51°F) | 0.99" |
| 1974 | 14°C (58°F) | 3°C (37°F) | 0" |
| 1973 | 16°C (60°F) | 7°C (44°F) | 0" |
| 1972 | 19°C (67°F) | 11°C (52°F) | 0.58" |
| 1971 | 20°C (68°F) | 9°C (48°F) | 0" |