eaglercraft-1.8/sources/main/java/net/optifine/config/Weather.java

package net.optifine.config;

import net.minecraft.world.World;

public enum Weather {
	CLEAR, RAIN, THUNDER;

	public static Weather getWeather(World world, float partialTicks) {
		float f = world.getThunderStrength(partialTicks);

		if (f > 0.5F) {
			return THUNDER;
		} else {
			float f1 = world.getRainStrength(partialTicks);
			return f1 > 0.5F ? RAIN : CLEAR;
		}
	}
}