Friday was a surprising day for residents and holidaymakers on the small Mediterranean island of Corsica. At breakfast time the wind swung around to the east-southeast and the temperature shot up by 9 degrees Celsius. At the same time, the wind strength picked up and visibility dropped.

This turned out to be a hot, dusty, windy day, the result of a sirocco from North Africa. These are irregular wind events, although this year Tunisia has experienced quite a few. In fact Tunis, the country’s capital, hit 40C on Monday, 11C above normal but not a record.

Usually, such a wind would become cooler and more humid by the time it reached Corsica from the African coast. On Friday it stayed dry and dusty with a relative humidity of 12 percent. Compare that with Thursday at 26C and 40 percent. It is the relative humidity that determines whether we, as warm-blooded beings, can bear the heat.

In contrast, Corsica’s capital, Ajaccio, did make a new record. A measurement of 40.1C. This beats the standing June record by 1.6 degrees and is only shy of the all-time record of 40.3C set in July 1983.

Qataris have survived 47C again this month with humidity readings below 1 percent. Indians and Pakistanis have endured 50C but with similarly low relative humidity. Anything much more than that becomes unbearable as humans cannot cool down by the normal method of perspiration.

Luckily for those on Corsica, it was record-breakingly hot for only one day, although the combination of high temperatures and winds gusting to at least 65 kilometres per hour caused schools to close.

Saturday returned to normal, temperature-wise at 25C, but even with the breeze in the southwest, the Saharan dust remained in the air.