Temperatures will be in the 33–35C range from Monday, June 24th to Wednesday, June 26th, government weather agency MeteoSwiss said in a statement.
The forecaster noted that while temperatures might only just hit the 33C mark on Monday, it was almost certain that the thermometer would pass this barrier on Tuesday and Wednesday.
MeteoSwiss added that some weather modelling suggested a cold front would then pass through on Wednesday, possibly preceded by storms. However, there is a good chance that temperatures will remain higher than usual beyond the middle of next week.
But it remains to be seen whether any Swiss records for June will fall by the wayside. The hottest June day on record in Zurich was 36C, while it was 36.4C in Geneva and 33.9C in Bern.
The overall national June record is held by Basel (36.9C).
In the meantime, before next week's heatwave hits, the thermometer will top out in the low 20s across most of Switzerland tomorrow, Friday, before things start to warm up on Saturday, when temperatures in the high 20s will be the order of the day.
MeteoSwiss is warning people to avoid strenuous exercise, eat lightly and drink plenty of liquid during the hot spell.