The average server room worker does a lot to protect sever equipment from damage. They use specially designed server rack cabinets to keep their equipment safe from external factors, and have various backup systems to protect their equipment from power surges. When it comes to external threats to sever security, water may be the biggest and most troublesome. It doesn't take an IT worker to know that electronics and water don't mix, and a few drops of moisture can cause catastrophic problems.
Some server rooms have elaborate systems in place to monitor the moisture content of a room, but if you want to protect your servers you're going to need to be aware of what could cause moisture and water accumulation. If you're worried about water affecting your servers you shouldn't be concentrating on the weather, since there are plenty of other more common ways water can get into your server room.
Air conditioning leakage
This is a common water hazard in server rooms since so many rely on powerful air conditioners to keep the room cool. Air conditioners need water in order to function, and a ruptured pipe or a leaking clamp of an air condition system can cause a lot of problems. Frozen pipes and components can also be an issue since they'll drip a significant amount of water once they thaw. The best way to avoid AC problems is to make sure routine maintenance is performed to ensure that it's running efficiently.
Condensation can easily form on your server room windows and cause problems with moisture, and it can form anywhere else in your room in the right conditions. Condensation can be difficult to detect at times, and the easiest way to keep it from affecting your servers is to use a moisture detection system to alert you if conditions in the server room become too moist. If possible, you should also consider putting in a request for maintenance to apply a waterproofing surface finish to exterior walls to prevent the rain and moisture from entering the building through cracks and other small areas.
This problem ties in with potential problems that can come from air conditioning units. Structural defects in pipes could lead to water dripping in from the roof, and problems with ceiling sprinklers in fire systems can cause significant water damage. If you're concerned about the structural integrity of certain systems in your building, you should talk with whoever is in charge of maintenance to explain the importance of having certain systems repaired and up to date to avoid potential server problems.