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Live forecasts update automatically; written guidance last reviewed 20 June 2026 by the Civic Affairs weather desk. Data from national met services via Open-Meteo.
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The 21-day forecast for London, shown in the live forecast above, indicates broad weather trends rather than precise day-to-day details. Use it to plan long-term activities, but check shorter-range forecasts – such as the 10-day forecast – closer to the time for better accuracy.
How reliable is a 21-day weather forecast for London?
Forecast confidence drops significantly beyond 10–14 days. The 21-day outlook is most useful for identifying general patterns – for example, whether a period of unsettled weather is likely – rather than predicting exact temperatures or rainfall at a specific hour. The Met Office describes such ranges as “long-range” and emphasises they are best used alongside regular updates.
What does the 21-day forecast include?
The live forecast above shows daily summaries – typically high and low temperatures, precipitation probability, and wind strength. It does not provide an hourly breakdown, as that level of detail is only reliable for the first few days. For a more granular view, you can look at weather london 14 days or the bbc weather london 15 day forecast, both of which offer similar trend information. Some providers, like AccuWeather, also extend to a 28 day weather forecast london, but the same reliability caveats apply.
Is a 21-day forecast accurate?
No forecast is fully accurate 21 days ahead. The Met Office rates its long‑range outlooks as a guide to the general weather type (e.g., unsettled or settled) rather than a day‑by‑day prediction. Expect larger swings between updates.
How often is the 21‑day forecast updated?
Most providers, including the Met Office and BBC Weather, refresh their long‑range forecasts once or twice a day. The live forecast above updates automatically – check the timestamp to see when it was last run.
Where can I check a 21‑day forecast for London?
You can use the Met Office website (enter “21 day weather forecast london met office”), BBC Weather, or other services such as AccuWeather. For a quick overview, the live forecast above gives the latest data. For detailed planning, combine it with a 10‑day forecast or the UK weather hub.