London, GB weather research: 2015–2024
An evidence-backed analysis of London using ERA5 via Open-Meteo (ECMWF/Copernicus). Read the static monthly and annual tables, dated extrema and reproducible methods below. This is a model reconstruction, not a measured city-site report.
London: a ten-year seasonal reading
Across 3,653 complete local days from 2015 through 2024, this requested London point has a mean daily maximum of 15.1 °C and a mean daily minimum of 8.3 °C. These describe the average daily highs and lows, not the average temperature throughout the day. The average annual precipitation total is 692.3 mm, with 130.5 days per year reaching at least 1 mm. The annual figures summarise this particular decade; they should not be presented as permanent city climate characteristics.
The warmest calendar month by mean daily maximum is July, at 22.5 °C, compared with 8.0 °C in the coolest month, January. That is a 14.6 °C seasonal difference. The corresponding mean daily minima are 14.3 °C and 2.8 °C. For itineraries that begin early or finish after sunset, those lower-temperature averages are a useful separate consideration; neither number specifies an hourly temperature or rules out an unusually hot or cold day.
The wettest month by average total is October, with 71.4 mm, while April has the lowest average total at 40.7 mm. Their difference is 30.7 mm. Precipitation here includes snow water equivalent as well as rain. Total amount and frequency answer different questions: March has the largest sampled wet-day frequency, 40.6%. A month with a modest total can still contain several wet days, and this daily dataset cannot identify how many hours were dry.
The wettest annual total in the sample is 2024, at 843.4 mm; the driest is 2018, at 568.9 mm. The 274.5 mm spread shows why relying on one remembered year can be misleading. The annual table makes that variation inspectable rather than hiding it inside a single average. Ten annual values alone are not a trend test or an attribution study, and the selected decade may differ from earlier or later periods.
For a like-for-like comparison, Paris uses the same ERA5 model, dates, variables and wet-day threshold. London has a 1.7 °C lower mean daily maximum and 49.2 mm less average annual precipitation. Compare monthly rows before choosing between destinations: an annual contrast can conceal different seasonal timing. Each location uses its own returned local time zone, so calendar-day extremes are not necessarily simultaneous events.
London extends along the Thames in southeast England. The river corridor and a large built-up area make a central point different from an exposed outer suburb or park. Do not assume this grid summary describes every borough. Geographic context supports these location descriptions, not additional weather observations. The reconstruction does not measure neighbourhood heat, wind shelter, drainage, flood risk or terrain effects at a venue. A nearby station catalog entry, if consulted in the directory, is not the source of the numbers in these tables.
For travel or an outdoor event, use the warmer-month contrast to discuss thermal comfort and the wet-day frequency to plan flexible activities, shelter and alternative dates. The frequency is an empirical fraction of sampled days, not a guaranteed forecast probability for a future booking. Check an up-to-date forecast close to the event and investigate the exact venue separately. The extrema below are the most extreme daily values within this model sample, with every tied date retained; they are not all-time observed city records or design thresholds for infrastructure.
Monthly evidence: 2015–2024
| Month | Days sampled | Mean daily high (°C) | Mean daily low (°C) | Average precipitation (mm/month) | Wet days (10-year count) | Average wet days/month | Wet-day frequency |
|---|---|---|---|---|---|---|---|
| January | 310 | 8.0 | 2.8 | 57.9 | 113 | 11.3 | 36.5% |
| February | 283 | 9.2 | 3.7 | 49.6 | 104 | 10.4 | 36.7% |
| March | 310 | 11.0 | 4.8 | 55.2 | 126 | 12.6 | 40.6% |
| April | 300 | 13.8 | 5.8 | 40.7 | 100 | 10.0 | 33.3% |
| May | 310 | 17.4 | 9.2 | 56.0 | 106 | 10.6 | 34.2% |
| June | 300 | 20.7 | 12.3 | 60.9 | 96 | 9.6 | 32.0% |
| July | 310 | 22.5 | 14.3 | 55.3 | 101 | 10.1 | 32.6% |
| August | 310 | 22.1 | 14.2 | 60.4 | 104 | 10.4 | 33.5% |
| September | 300 | 19.5 | 11.9 | 57.8 | 108 | 10.8 | 36.0% |
| October | 310 | 15.5 | 9.3 | 71.4 | 115 | 11.5 | 37.1% |
| November | 300 | 11.1 | 5.9 | 61.9 | 109 | 10.9 | 36.3% |
| December | 310 | 9.4 | 5.0 | 65.1 | 123 | 12.3 | 39.7% |
The sum of the twelve unrounded average monthly precipitation totals is 692.3 mm/year. February includes three leap days (283 sampled days); other months have 300 or 310. Display rounding can cause small differences when adding visible rows.
Annual evidence and completeness
| Year | Days / expected | Complete | Mean daily high (°C) | Mean daily low (°C) | Precipitation (mm/year) | Wet days |
|---|---|---|---|---|---|---|
| 2015 | 365 / 365 | Yes | 14.8 | 8.1 | 637.6 | 136 |
| 2016 | 366 / 366 | Yes | 14.6 | 8.1 | 582.5 | 117 |
| 2017 | 365 / 365 | Yes | 14.7 | 8.3 | 647.3 | 129 |
| 2018 | 365 / 365 | Yes | 15.4 | 8.2 | 568.9 | 106 |
| 2019 | 365 / 365 | Yes | 14.9 | 7.9 | 736.8 | 139 |
| 2020 | 366 / 366 | Yes | 15.4 | 8.4 | 668.7 | 122 |
| 2021 | 365 / 365 | Yes | 14.3 | 7.8 | 788.2 | 134 |
| 2022 | 365 / 365 | Yes | 15.9 | 8.5 | 664.4 | 136 |
| 2023 | 365 / 365 | Yes | 15.4 | 8.7 | 785.2 | 141 |
| 2024 | 366 / 366 | Yes | 15.1 | 8.8 | 843.4 | 145 |
Daily extrema within this sample
| Metric | Value | Date(s) |
|---|---|---|
| Highest daily maximum | 37.7 °C | 2022-07-19 |
| Lowest daily minimum | -5.6 °C | 2022-12-15 |
| Largest daily precipitation total | 34.7 mm | 2021-06-18 |
Coordinates, provenance and reproducible methods
- Requested city-centre research coordinates: 51.5074, -0.1278
- Separate directory catalog coordinates: 51.50853, -0.12574 (all-the-cities); the prefilled search below still uses this catalog point.
- Returned model-grid coordinates: 51.5, -0.25; time zone Europe/London. Requested and returned points are not interchangeable station locations.
- Source: ERA5 via Open-Meteo (ECMWF/Copernicus); explicit model selection: ERA5.
- Coverage: 2015-01-01 through 2024-12-31; retrieved 2026-10-05T23:04:14.803Z.
ERA5 reanalysis combines a numerical model with assimilated observations. These are gridded model reconstructions, not direct station observations or measurements at the requested city-centre site. The API returns a snapped grid location; do not infer neighbourhood-scale precision from the requested decimal coordinates. This ten-year baseline is not a WMO 30-year normal.
- Arithmetic mean of all daily maxima/minima in the calendar month across all ten years; annual means use all days in that year. These are not mean daily temperatures.
- Sum all daily precipitation in each calendar month across ten complete years, then divide by ten for average monthly totals; annual-normal total is the sum of the twelve average monthly totals.
- Daily precipitation >= 1 mm; monthly average count = total monthly wet days / 10; frequency = wet days / all sampled days (fraction, not a forecast probability).
- Maximum daily maximum, minimum daily minimum and maximum daily precipitation in this period; exact numeric ties retain every local date in chronological order. Not all-time station records.
- All 3653 consecutive local daily dates required, including February 29 in 2016, 2020 and 2024; no missing/nonfinite values, interpolation or zero filling.
- 2015–2024 ten-year model reconstruction summary, not a WMO 30-year climate normal; precipitation includes rain and snow water equivalent.
All arrays must contain the same 3,653 consecutive daily dates with finite values and the expected °C/mm units before this research report is generated. Missing data are rejected, never replaced with zero. Derived tables are recomputed from the saved daily arrays during validation; calculations retain full precision, and visible numbers are rounded to one decimal. Monthly ranking ties use all tied months; annual ranking ties use chronological order.
Reproduce the retrieval with the full five-location Open-Meteo query. The JSON evidence and provenance contains that URL, the retrieval timestamp, requested and provider coordinates, units, daily inputs and unrounded aggregates. Consult the Historical Weather API documentation and ECMWF ERA5 description for source limitations.
Continue the historical weather search
Open historical weather search for London using the original directory coordinates. A search may select a different source or period; compare its provenance before treating it as equivalent to this reconstruction.
Nearby directory locations
These are the closest other entries in our GB city directory, ordered by calculated straight-line distance between catalog coordinates. They are not a complete list of nearby settlements.