The mercury rose to more than 21C in Chur in the canton of Graubünden and Binningen in the canton of Basel-Country, the warmest places in the country.
Records were set in La Chaux-de-Fonds in the canton of Neuchâtel (20.4C), Crans-Montana in the canton of Valais (19C), Samedan in the canton of Graubünden (17.7C), Chasseral in the canton of Bern (16.9C) and Mount Pilatus straddling the cantons of Lucerne and Obwalden (15.7C).
“Today is a day of absolute records,” Roger Perret of MeteoNews told the ATS news agaency.
The mild weather is exceptional in Switzerland for this time of year, he said.
The cause of the warmer than usual conditions was a large high pressures system centred over Europe.
Perret said the situation had nothing to do with climate change.
“It's a meteorological situation completely special,” he said.
“Next year could be totally different.”
MeteoSwiss, the national weather office, forecast slightly cooler weather for Monday and Tuesday but with warmer than average temperatures.
The thermometer should rise to 19 degrees in Sion (Valais), Lugano (Ticino) and Chur on Monday, the office said.