Every factor that could affect the outcome of a tennis match comes under minute scrutiny, including the weather.
Temperature is fairly straightforward. On a hot day, the pressure inside the ball increases, it bounces better and the game is faster. Heat also fractionally increases string tension in the racket.
Humidity is more complex. Some players believe that humid, heavy air slows the ball down. Technically though, humid air is lighter than dry air. Nor does humidity fluff up the fuzz on a tennis ball, increasing air friction, as some claim. Humidity mainly affects the players themselves, making them sweat more, and playing takes more effort. This may give an impression of “heavy air”.
Light drizzle has several effects. A saturated tennis ball is about 1% heavier than a dry one, fractionally slowing play. It is also harder to impart spin to a wet surface, blunting the edge of a skilled player and making rallies longer.
Whenever there is a competition at Wimbledon though, one type of weather is usually the biggest concern. Centre Court has had a retractable rain cover since 2009; this also requires an extensive air circulation system to keep the temperature and humidity inside at tolerable levels. At least play can continue at Centre Court when other matches are rained off.