humidity

“The combinations of temperature and humidity we are seeing this summer on average in New York City are comparable to summertime stickiness in Florida,” Casey Ivanovich, the inventor of the stickiness index, said.

Heat and humidity can affect the court speed, and balls and string technology also play a significant part.

The key stories in a race that was designated Formula 1's first 'heat hazard' grand prix, testing the drivers to the limit in temperatures of 30C and humidity of 72%, were:

The FIA declared the Singapore race a 'heat hazard' because it surpasses an index that combines high temperatures with high humidity.

The idea of a driver-cooling system was intimated after the 2023 Qatar Grand Prix, when heat and humidity left several drivers on the brink of collapse.