Weather on September 21 in London
Historical weather data for September 21 in London, United Kingdom
Based on 55 years of data from HAMPSTEAD
About This Date
September 21st in London, United Kingdom typically brings mild fall weather, with average highs around 18°C and lows near 11°C. Over 55 years of records, the warmest September 21st was in 2006 (22°C average), while the coldest was 1979 (9°C) — a 23°F range across recorded history. Rain or other precipitation has occurred on about 44% of September 21st dates historically, with the wettest September 21st recording 2.69" of rain. The last decade has been 1.4°F cooler on this date compared to 20-30 years ago.
The last decade has been 1.4°F cooler on this date compared to 20-30 years ago.
Planning for September 21st in London? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Year by Year History
| Year | High | Low | Precip (mm) |
|---|---|---|---|
| 2025 | 15°C (59°F) | 8°C (47°F) | 0 mm |
| 2024 | 24°C (76°F) | -- | 0 mm |
| 2023 | 19°C (66°F) | -- | 68 mm |
| 2022 | 21°C (70°F) | 13°C (56°F) | 0 mm |
| 2021 | 22°C (72°F) | 10°C (50°F) | 0 mm |
| 2020 | -- | 14°C (57°F) | 0 mm |
| 2019 | -- | 12°C (53°F) | 0 mm |
| 2018 | 12°C (54°F) | 9°C (48°F) | 1 mm |
| 2017 | 17°C (63°F) | 12°C (53°F) | 5 mm |
| 2016 | -- | 15°C (59°F) | 0 mm |
| 2015 | 14°C (57°F) | 12°C (53°F) | 33 mm |
| 2014 | 18°C (65°F) | 11°C (51°F) | 0 mm |
| 2013 | 18°C (65°F) | 9°C (49°F) | 0 mm |
| 2012 | 16°C (60°F) | 10°C (50°F) | 1 mm |
| 2011 | 19°C (66°F) | 12°C (54°F) | 0 mm |
| 2010 | 23°C (73°F) | 11°C (51°F) | 0 mm |
| 2009 | 19°C (67°F) | 11°C (51°F) | 0 mm |
| 2008 | 19°C (66°F) | 9°C (48°F) | 0 mm |
| 2007 | 19°C (66°F) | 14°C (57°F) | 0 mm |
| 2006 | 28°C (82°F) | 17°C (62°F) | 11 mm |
| 2005 | 21°C (70°F) | 13°C (56°F) | 0 mm |
| 2004 | 18°C (64°F) | 9°C (48°F) | 0 mm |
| 2003 | 21°C (70°F) | 13°C (55°F) | 0 mm |
| 2002 | 17°C (62°F) | 12°C (53°F) | 0 mm |
| 2001 | 18°C (64°F) | 9°C (49°F) | 0 mm |
| 2000 | 22°C (71°F) | 8°C (47°F) | 5 mm |
| 1999 | 21°C (69°F) | 12°C (53°F) | 1 mm |
| 1998 | 18°C (64°F) | 13°C (56°F) | 0 mm |
| 1997 | 20°C (68°F) | 8°C (47°F) | 0 mm |
| 1996 | 14°C (57°F) | 11°C (51°F) | -- |
| 1995 | 19°C (66°F) | 9°C (49°F) | 0 mm |
| 1994 | 18°C (64°F) | 9°C (49°F) | 1 mm |
| 1993 | 18°C (65°F) | 13°C (55°F) | 0 mm |
| 1992 | 16°C (60°F) | 12°C (54°F) | 2 mm |
| 1991 | 18°C (64°F) | 11°C (51°F) | 23 mm |
| 1990 | 14°C (57°F) | 9°C (48°F) | 6 mm |
| 1989 | 19°C (66°F) | 12°C (54°F) | 1 mm |
| 1988 | 18°C (65°F) | 9°C (49°F) | 10 mm |
| 1987 | 18°C (65°F) | 16°C (60°F) | 2 mm |
| 1986 | 20°C (68°F) | 7°C (44°F) | 0 mm |
| 1985 | 21°C (70°F) | 12°C (53°F) | 7 mm |
| 1984 | 16°C (60°F) | 7°C (45°F) | 2 mm |
| 1983 | 17°C (62°F) | 9°C (49°F) | 9 mm |
| 1982 | 16°C (60°F) | 16°C (61°F) | 19 mm |
| 1981 | 18°C (65°F) | 11°C (52°F) | 0 mm |
| 1980 | 19°C (66°F) | 15°C (59°F) | 14 mm |
| 1979 | 13°C (55°F) | 6°C (43°F) | 1 mm |
| 1978 | 22°C (72°F) | 9°C (49°F) | 0 mm |
| 1977 | 13°C (56°F) | 7°C (45°F) | 1 mm |
| 1976 | 18°C (65°F) | 14°C (57°F) | 0 mm |
| 1975 | 18°C (65°F) | 6°C (43°F) | 0 mm |
| 1974 | 14°C (58°F) | 9°C (48°F) | 9 mm |
| 1973 | 16°C (60°F) | 9°C (48°F) | 0 mm |
| 1972 | 20°C (68°F) | 8°C (46°F) | 0 mm |
| 1971 | 23°C (73°F) | 11°C (51°F) | 0 mm |