If the problem is solely considered one of condensation, parking in a storage or different climate-controlled space in a single day ought to remove the issue, and gently making use of the brakes early in your driving day ought to make the noise much less distinguished or go away altogether. Below this circumstance, making use of WD-40 would possibly assist displace the water and quiet your brakes, however except you are going to do that each morning it will not actually be a helpful tactic.
Squeaky brakes may also be a sign that your brake pads are nearing the top of their life and want alternative, making the noise an essential security warning. Spraying WD-40 in your brakes may also injury the rubber seals on the caliper seals and brake strains, inflicting hydraulic fluid leaks and different doubtlessly harmful failures of your brake system. Typically the supply of brake noise is a caught drum (many autos have drum brakes on the rear wheels).
In case your drum brakes are sticking, use a brake lubricant as a substitute of WD-40, and apply it to the backing plate the place the brake shoe sits and to not the entrance brake rotors. Making use of brake lubricant between disc rotors and pads will severely compromise disc brake efficiency and will result in a crash.