Sun bathers soaked up the sunshine in all corners of the country, although the hottest spot was Basel, where the mercury rose to 26.9 degrees, according to MeteoNews.
Liestal, 17 kilometres south of Basel, came a close second with a high of 26.3 degrees, while in Sion, the capital of the canton of Valais, it reached 25.8 degrees.
The northern part of the country experienced the warmest conditions recorded so far this year, MeteoNews said, following a chilly start to spring.
The weather proved to be too warm in Bern for a soldier who was part of an honour guard that greeted French President François Hollande during his state visit in the Swiss capital on Wednesday — he collapsed from too much exposure to the sun.
Clouds are forecast to bring cooler weather to the country on Thursday, although Basel is expected to record a high of around 25 degrees, while it should get to 26 degrees in Chur, in the canton of Graubünden to the east, MeteoSwiss, the national weather office said.
But the weather office was calling for rain across Switzerland on Friday and Saturday, accompanied by a progressive drop in temperatures.
By Saturday, the high is only expected to hit eight degrees in La Chaux-de-Fonds in the canton Neuchâtel, and nine degrees in Saint Gallen.
A gradual clearing is predicted for Sunday in most parts of Switzerland with highs ranging from 11 to 18 in major Swiss cities.