Check the timing.
try a radiator cap......or you have a head gasket leak.
it can..rain has NOTHING to do with your radiator or the thermostat
Take your thermostat out and put everything back together, run your car without a thermostat... If your car no longer overheats, replace your thermostat.
Be sure the thermostat is not installed backwards.
It could be the thermostat. Open up the radiator cap when it is hot and see if the water is flowing in the radiator. If it is not then it may be a thermostat.
check the heater core stopped up radiator
Your thermostat is stuck closed. you will need to replace it. The thermostat controls the circulation through the radiator - when the engine heats up the thermostat is meant to switch circulation from just-engine to engine+radiator. Sounds like this isn't happening.
Thermostat regulator is malfunctioning, water pump pulley could be bad, gas bubble in radiator hose.
Blown head gasket?
clogged radiator or bad water pump
Low coolant, inoperative radiator fan, failed water pump, restricted radiator, head gasket failed, stuck thermostat.
Be care-full my radiator blew up and burnt me. I replaced Radiator, thermostat, and water pump. Timing belt is in the way so I replaced it too. OK Now