London in September
In September, London has 49.8 mm (1.96 in) of rain, a daily high of 20.2 °C (68.4 °F) and a daily low of 12.3 °C (54.1 °F), as 1991-2020 means; figures in brackets are converted.
Last updated : first sourced version.
Key figures
Weather in September, 1991-2020 means
- High
- 20.2 °C (68.4 °F)
- Low
- 12.3 °C (54.1 °F)
- Rain
- 49.8 mm (1.96 in)
- Sunshine
- no data
Climate normals 1991-2020, computed by the national weather service and submitted to the World Meteorological Organization. Checked .
Station: St James's Park, 0.4 km from the city centre point.
Figures in brackets are converted: °F = °C × 9 ÷ 5 + 32, to 1 decimal; inches = mm ÷ 25.4, to 2 decimals.
High: mean daily maximum temperature. Low: mean daily minimum temperature. Rain: mean monthly precipitation total.
Notes. Sunshine: the source file has this measure for 0 of 12 months.
Daylight on 15 September 2026
- Sunrise
- 06:35 local time
- Sunset
- 19:15 local time
- Day length
- 12 h 40 min
Sunrise and sunset computed with the NOAA Solar Calculator equations, to the minute, for 15 September 2026. Day length in hours and minutes. How we compute this
Source: NOAA Solar Calculator equations, checked .
Month by month
Each month: daily high in °C, then rain in mm, 1991-2020 means.
Climate normals 1991-2020, computed by the national weather service and submitted to the World Meteorological Organization. Checked .
This month against the year
| Measure | September | Rank |
|---|---|---|
| Daily high | 20.2 °C | 4th warmest of 12 months |
| Daily low | 12.3 °C | 4th warmest of 12 months |
| Rain | 49.8 mm | 6th driest of 12 months |
| Sunshine | no data | no data |
| Day length | 12 h 40 min | 6th longest of 12 months |
Each value is ranked among the 12 monthly values of the same measure. Equal values share a rank. How we compute this
Climate normals 1991-2020, computed by the national weather service and submitted to the World Meteorological Organization. Checked .
Day length: NOAA Solar Calculator equations, checked .
Public holidays this month
September 2026: none.
Typed from the official list and re-checked, .
September 2027: none.
Typed from the official list and re-checked, .
Source: Official public holiday list (gov.uk), checked .
Same month in other cities
| City | High, °C | Low, °C | Rain, mm |
|---|---|---|---|
| Amsterdam | 19.2 | 11.0 | 84.4 |
| Barcelona | 26.7 | 18.8 | 86.1 |
| Berlin | 19.9 | 10.9 | 46.6 |
| Buenos Aires | 19.7 | 10.6 | 80.6 |
| Hong Kong | 30.5 | 26.1 | 321.4 |
| Los Angeles | 28.3 | 17.9 | 3.3 |
| New York | 24.6 | 16.8 | 109.5 |
| Osaka | 29.5 | 21.9 | 152.8 |
| Paris | 21.5 | 13.0 | 44.7 |
| Prague | 20.1 | 9.9 | 41.8 |
| Rome | 26.7 | 16.0 | no data |
| Singapore | 31.6 | 25.2 | 124.9 |
| Tokyo | 27.5 | 20.3 | 224.9 |
| Vienna | 21.1 | 12.0 | 64.1 |
Source: Climate normals 1991-2020, computed by each city's national weather service and submitted to the World Meteorological Organization, checked ; U.S. Climate Normals 1991-2020, NOAA, checked ; Hong Kong: our 1991-2020 mean of the Hong Kong Observatory daily climate series on DATA.GOV.HK, checked ; Singapore: our 1991-2020 mean of the National Environment Agency monthly climate series on data.gov.sg, checked . Each city's page names its station.
Sources
- WMO Climatological Standard Normals for 1991-2020 (NCEI Accession 0253808), WMO Member Nations (each national weather service's own submission); archived by NOAA National Centers for Environmental Information. Attribution: WMO Member Nations (2023). WMO Climatological Standard Normals for 1991-2020 (NCEI Accession 0253808). Station files named in each record. NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/800j-vn07. Accessed on the check date shown. Licence: No licence stated. Published by NOAA NCEI for WMO; citation requested. Checked .
- U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020), NOAA National Centers for Environmental Information. Attribution: Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). Station files named in each record. NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed on the check date shown. Licence: No licence stated; citation requested. Checked .
- Hong Kong Observatory daily climate series on DATA.GOV.HK, Hong Kong Observatory, Government of the Hong Kong Special Administrative Region; published on DATA.GOV.HK. Attribution: Hong Kong Observatory daily series of maximum temperature, minimum temperature, total rainfall and total bright sunshine, from DATA.GOV.HK (https://data.gov.hk/en/), read on the check date shown. The Government of the Hong Kong Special Administrative Region and the Hong Kong Observatory own the intellectual property rights in the data. With attribution to the Government of the Hong Kong Special Administrative Region, the Hong Kong Observatory and DATA.GOV.HK. The 1991-2020 means are computed by City by Month, not by the Observatory. Licence: Terms and Conditions of Use of DATA.GOV.HK, version 1.2. Checked .
- National Environment Agency monthly climate series on data.gov.sg, National Environment Agency, Singapore; published on data.gov.sg. Attribution: Contains information from Surface Air Temperature - Monthly Mean Daily Maximum, Surface Air Temperature - Monthly Mean Daily Minimum and Rainfall - Monthly Total, accessed on the check date shown from the National Environment Agency on data.gov.sg, which is made available under the terms of the Singapore Open Data Licence version 1.0 (https://data.gov.sg/open-data-licence). The 1991-2020 means are computed by City by Month, not by the Agency, and the Agency does not endorse them. Licence: Singapore Open Data Licence version 1.0. Checked .
- NOAA Solar Calculator equations, computed locally, NOAA Global Monitoring Laboratory (method); City by Month (computation). Attribution: Computed with the NOAA Solar Calculator method (no NOAA endorsement implied). Licence: Method, not data. Checked .
Official sources
- Official public holiday list (gov.uk). Checked .
Cite this page: City by Month. "London in September: weather, daylight, holidays". https://citybymonth.com/cities/united-kingdom/london/september/. Last updated 2 October 2026.