Weather on September 21 in Ottawa
Historical weather data for September 21 in Ottawa, Canada
Based on 55 years of data from OTTAWA CDA
About This Date
September 21st in Ottawa, Canada typically brings mild fall weather, with average highs around 20°C and lows near 9°C. Over 55 years of records, the warmest September 21st was in 2002 (24°C average), while the coldest was 1973 (6°C) — a 33°F range across recorded history. Rain or other precipitation has occurred on about 45% of September 21st dates historically, with the wettest September 21st recording 3.1" of rain. Temperatures on this date have remained relatively stable over the past several decades.
Temperatures on this date have remained relatively stable over the past several decades.
Planning for September 21st in Ottawa? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Year by Year History
| Year | High | Low | Precip |
|---|---|---|---|
| 2025 | 24°C (76°F) | 2°C (35°F) | -- |
| 2024 | 26°C (79°F) | 14°C (58°F) | 0" |
| 2023 | 22°C (71°F) | 6°C (42°F) | 0" |
| 2022 | 23°C (73°F) | 12°C (54°F) | 0.46" |
| 2021 | 22°C (72°F) | 13°C (56°F) | 0" |
| 2020 | 18°C (64°F) | 1°C (34°F) | 0" |
| 2019 | 27°C (81°F) | 11°C (52°F) | 0" |
| 2018 | 28°C (83°F) | 12°C (54°F) | 2.7" |
| 2017 | 26°C (79°F) | 14°C (57°F) | 0" |
| 2016 | 26°C (79°F) | 12°C (54°F) | 0" |
| 2015 | 21°C (69°F) | 6°C (42°F) | 0" |
| 2014 | 23°C (73°F) | 18°C (64°F) | 1.42" |
| 2013 | 21°C (69°F) | 12°C (54°F) | 2.35" |
| 2012 | 17°C (63°F) | 13°C (55°F) | 1.72" |
| 2011 | 24°C (76°F) | 8°C (47°F) | 0.26" |
| 2010 | 19°C (67°F) | 3°C (38°F) | 0.63" |
| 2009 | 23°C (74°F) | 3°C (37°F) | 0" |
| 2008 | 16°C (61°F) | 7°C (44°F) | 0" |
| 2007 | 26°C (79°F) | 11°C (52°F) | 0" |
| 2006 | 16°C (61°F) | 3°C (38°F) | 0.07" |
| 2005 | 26°C (78°F) | 10°C (50°F) | 0" |
| 2004 | 24°C (75°F) | 12°C (53°F) | 0" |
| 2003 | 19°C (67°F) | 11°C (52°F) | 0" |
| 2002 | 28°C (82°F) | 21°C (70°F) | 0" |
| 2001 | 24°C (76°F) | 15°C (59°F) | 0.57" |
| 2000 | 18°C (65°F) | 14°C (57°F) | 0.14" |
| 1999 | 14°C (58°F) | 6°C (43°F) | 0" |
| 1998 | 29°C (85°F) | 13°C (56°F) | 0.13" |
| 1997 | 13°C (55°F) | 4°C (40°F) | 0" |
| 1996 | 24°C (75°F) | 13°C (55°F) | 0" |
| 1995 | 17°C (63°F) | 12°C (54°F) | 0.02" |
| 1994 | 24°C (76°F) | 10°C (50°F) | 0" |
| 1993 | 18°C (64°F) | 2°C (35°F) | 0" |
| 1992 | 20°C (68°F) | 9°C (48°F) | 1.62" |
| 1991 | 13°C (56°F) | 1°C (33°F) | 0" |
| 1990 | 17°C (62°F) | 7°C (44°F) | 1.22" |
| 1989 | 27°C (80°F) | 11°C (51°F) | 0" |
| 1988 | 17°C (62°F) | 12°C (54°F) | 0" |
| 1987 | 13°C (56°F) | 10°C (50°F) | 0.02" |
| 1986 | 18°C (64°F) | 7°C (45°F) | 0" |
| 1985 | 19°C (67°F) | 16°C (60°F) | 0" |
| 1984 | 17°C (62°F) | 5°C (41°F) | 0" |
| 1983 | 26°C (79°F) | 14°C (57°F) | 3.1" |
| 1982 | 18°C (65°F) | 9°C (49°F) | 0" |
| 1981 | 13°C (56°F) | 4°C (39°F) | 0.04" |
| 1980 | 16°C (61°F) | 8°C (46°F) | 0.78" |
| 1979 | 18°C (64°F) | 12°C (54°F) | 0.66" |
| 1978 | 21°C (69°F) | 15°C (59°F) | 0.32" |
| 1977 | 9°C (48°F) | 7°C (44°F) | 0.18" |
| 1976 | 14°C (58°F) | 7°C (44°F) | 0.1" |
| 1975 | 17°C (63°F) | 10°C (50°F) | 0.18" |
| 1974 | 13°C (55°F) | 9°C (48°F) | 0.1" |
| 1973 | 13°C (56°F) | -1°C (31°F) | 0.18" |
| 1972 | 22°C (72°F) | 6°C (42°F) | 0" |
| 1971 | 18°C (64°F) | 12°C (54°F) | 0" |