September Weather Forecast 2025

September Weather Forecast: What to Expect This Autumn Transition

Introduction

September marks a poignant shift from summer’s lingering warmth into the crisp embrace of autumn. As seasons transition, weather patterns become more variable—ranging from lingering sunny spells to sudden rainstorms, cooling temperatures, and striking contrasts. This article explores what typically unfolds across the UK and Europe during September, backed by the latest forecasts, climate normals, and historical trends.

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1. Climate Averages: UK & Europe at a Glance

United Kingdom

• Temperatures: Across the UK, typical September highs hover around 17 °C (62 °F) and lows near 9 °C (48 °F). Current Results

• In London, daytime highs gradually fall from 20 °C (68 °F) on September 1 to about 18 °C (64 °F) by month’s end, with night temperatures dipping from 15 °C (59 °F) to around 12 °C (54 °F). Holiday WeatherLondon Perfect

• Regional variations reveal averages ranging from 10–18 °C, roughly 8 cm (3 inches) of rainfall, around 12 rainy days, and approximately 6 hours of sunshine per day. Global Highlights

• London specifics: Typical daily weather shows highs of 20 °C (68 °F) and lows of 10 °C (49 °F). Rain probability is around 20%, with about 8.4 mm on rainy days. Average sunshine spans 11.6 hours, daylight averages 12.7 hours, humidity sits around 78%, and wind speeds average 15.7 mph. Wanderlog

• In Manchester, highs dip from around 19 °C (66 °F) to 16 °C (60 °F) during September; lows go from 12 °C (53 °F) to 9 °C (49 °F). Weather Spark

• England overall sees average minimum/maximum of 10.4 °C / 18.1 °C, with mean daily temperature around 14.3 °C. Climate to Travel

• Sunlight & precipitation patterns: London, Manchester, and Newcastle show around 50% clear skies, 7–9 rainy days, moderate rainfall, and 12.6 hours of daylight (e.g., in London). Weather Spark

Continental Europe

• Western Europe: Averages include maximums of about 19 °C and minimums near 11 °C. TravelTriangle.com

• Eastern Europe: More favourable with average highs of 22 °C and nighttime lows dropping to 12 °C. TravelTriangle.com

• Mediterranean regions: Enjoy balmy conditions in September—average highs reaching 29 °C, making it ideal for beach outings. TravelTriangle.com

• For instance, France sees highs from 19 °C to 17 °C and lows from 14 °C to 11 °C by month-end. Weather Spark

• Data from Copernicus shows September 2024 was the second-warmest globally and in Europe with an average of 16.17 °C, warming trends that underscore our changing climate. Copernicus Climate Change Service+1

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2. Forecast Trends for September 2025

Even as monthly averages offer a baseline, recent forecasts suggest early autumn may bring fluctuating patterns.

UK Outlook

• Storms and unsettled weather are projected: Two notable systems are expected—one peaking around August 30, and another beginning September 3. These are likely to bring heavy rain, thunderstorms, hail, and gusty winds, especially in western and southern areas. The SunThe Sun

• Hurricane Erin’s remnants have already catalysed unstable weather—bringing strong winds, hail, and showers—while further unsettled conditions are likely to persist into September. The SunThe Times

• Tropical Storm Fernand’s remnants may further amplify weather disturbance via the jet stream, potentially delivering additional heavy rainfall and wind. The Times

• Overall mid-September pattern: Low-pressure systems dominate early in the month, ushering in showers, possible thunderstorms, and near-average temperatures. More stable spells are possible in between—but confidence in those remains low. The Sun

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3. Historical Highlights and Climate Insights

See-Saw of Extremes

• September heatwaves can still surprise. In 2023, the UK endured the longest September heatwave on record, with daily temperatures soaring above 32 °C, peaking at 35 °C, and ending with thunderstorm warnings. Wikipedia

• The legendary 1906 heatwave saw temperatures reach 35.6 °C in Bawtry—the hottest September temperature ever recorded in the UK to date. Wikipedia

Flooding Risks

• In 2024, heavy September rainfall placed the UK on alert for another autumn/winter flooding season. The Environment Agency warned of rising flood risks, urging stronger resilience planning. The Guardian

• Notably, in 2012, severe flooding impacted hundreds of homes in Wales, Yorkshire, and North East England after heavy September rainfall. Wikipedia

Climate Change Angle

• European land areas have warmed significantly more than the global average—up to nearly 2 °C since pre-industrial times—heightening the frequency of extreme heat events. Wikipedia

• New research shows compound extreme heat events in mid-latitude Europe have surged by roughly 10-fold since past decades—precisely the kind of volatility future Septembers may bring. arXiv

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4. SEO Snapshot: Key Insights for Readers

• Temperature Range: UK typical September highs average 17 °C, while continental highs range from 19–22 °C, and Mediterranean zones near 29 °C.

• Rainfall & Patterns: Expect 8 cm total rainfall, 12 rainy days in the UK, and 20% daily chance of rain in London. Forecasts warn of early-month storms and unsettled systems into September.

• Leftover tropical storms (like Erin and Fernand) still affect the weather in the UK and Europe, causing sudden changes and short periods of stormy weather

• Historical Extremes: September heatwaves are not uncommon—such as in 2023 or 1906. Flood risks also rise during wetter years—e.g., 2012.

• Climate Trends: Warming is intensifying September temperature extremes and variability.

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5. What This Means for You

• Travelers: Pack layers—light clothes for daytime warmth, plus a waterproof jacket. Weather can flip from sunny to stormy rapidly.

• People planning events or outdoor activities should check the weather forecast often, especially in early September, and be ready with backup plans for rain or wind.

• Gardeners & Farmers: Be ready for both late-season warmth and surprise showers or storms. Adjust planting and harvest timing accordingly.

• General Advice: September 2025 in the UK will likely be similar to past years, with some warm days mixed with sudden rain, wind, and cooler temperatures.

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Final Thoughts

September is a month of transition—and in 2025, it’s shaping up to be no different. Expect mild, fluctuating temperatures, a moderate chance of rain, particularly early in the month, and the occasional surprise event—be that a fleeting heatwave, heavy downpour, or a storm system-fed cooldown. Whether you’re traveling, planning events, or simply keeping an eye on the sky, September’s forecast underscores one theme: expect the unexpected.