September part with temperatures from high summer. The first weekend of the month will in fact be characterised by a new heat phase, with Saturday 5th and Sunday 6th September marked by temperatures between 33 and 35 degrees in many areas and peaks of 37-38 degrees, reaching up to 39 degrees in the South. The heat will remain the protagonist also at the beginning of next week, at least until Tuesday, September 8th, with mostly stable and sunny conditions. And while Italy prepares for a new taste of summer, the outlook for autumn and winter A more turbulent picture is beginning to emerge, especially in light of the strengthening El Niño and its possible effects on the climate in the coming months.
Weekend Weather Forecast for September 5-6: Sunny and hot, with temperatures reaching 39 degrees Celsius in the South.
Saturday 5rd September The sun will dominate practically all of Italy, with some cloud cover and the possibility of brief showers or isolated thunderstorms in the eastern Alps and Friuli Venezia Giulia in the afternoon. Domenica the picture will remain similar, with the more intense heat in the Center-SouthLarge cities will also be affected by the high values: Milan could reach 34-35 degrees, almost matching the September record of 34,6 degrees recorded in 2024, while Rome could reach 35-36 degrees close to the monthly record of 35,6°C. The heat, however, will not necessarily be accompanied by a particularly intense heat and the nights will remain relatively more livable. A few afternoon showers may affect the mountains, but they won't compromise the weekend's stability.
September weather forecast: rain and falling temperatures from Wednesday 9 September
After the last few days of heat, the picture could be… change from Wednesday 9 September, when fresher air from Northern Europe could reach Italy together with a disturbance. The worsening should initially affect the North part, to then extend to the Centro and South, with locally intense rain and thunderstorms especially between the North-East, the Alps and the Adriatic regions. The passage of the disturbed weather system would be accompanied by a sharp drop in temperatures, which in many areas could return below 30°C. The turning point, however, could only be temporary: already A further improvement is possible from Friday 11 September, with the return of good weather and temperatures still slightly above average.
El Niño, WMO alert: record heat and risk of extreme events until 2027
What is most worrying, however, is what could happen in the coming months.World Meteorological Organization (Omm) launched a alarm unprecedented for the strengthening of El Niño, a climatic phenomenon characterized by the periodic anomalous warming of the waters of the tropical Pacific, which could reach a very strong intensity by the end of 2026 and, with a probability close to 100%, persist until February 2027Equatorial Pacific temperatures are already up to 2,6 degrees Celsius above average, while below-surface temperatures exceed 8 degrees Celsius. Such a strong El Niño can alter temperatures and precipitation on a global scale, increasing the risk of droughts, floods, heat waves, and other extreme events. The WMO has therefore strengthened preparedness and early warning activities, while initial seasonal projections indicate possible effects also on the 2026-2027 winter, with below-average snowfall in much of Europe and more favourable conditions especially at high Alpine altitudes.
