I have a 2004 kia rio that won’t start when it rains or snow.

How many miles are on the odometer? It sounds like you need a tune-up with new spark plug wires. Bad or worn-out insulators on the wires will lead to severe mis-fires, especially when the air is highly humid. If this car is equipped with Coil-On-Plugs, it is probably bad coils.

I agree with busted . . . do the wires and plugs first, I don’t know about the coil packs either. Do you know if you have a coil? Distributor cap? I’d try the plugs and wires. Rocketman

Silicone is an insulator, and is water repellant. Use a silicone spray on the coils and ignition control. It might help.