02/06/2026
Heat period or heatwave – what’s the difference? 🌡️
Last week, Switzerland saw an intense early-summer heat event — over 30°C in May, weeks before summer even began.
Despite peaks of over 33°C, it was officially classified as a heat period, not a heatwave.
The reason is mathematical: A formal heatwave requires the 24-hour average temperature to exceed a critical threshold for three consecutive days. Because rural areas cooled down significantly at night, that official average wasn't met.
In cities, however, cooling down happens at a much slower pace. While open fields and green spaces outside the city begin to cool immediately after sunset, asphalt and concrete hold onto the daytime heat and release it very gradually.
This highlights a crucial point: General weather reports provide vital macro-data—but how fast and how effectively our immediate surroundings actually cool down is determined entirely by the local microclimate.
