I'm playing the reign of giants expansion as WX-78, and he's taking damage because he is wet.
It is raining, but I have an umbrella. However, the "wetness" meter keeps going up. How can I get dry? I'm dying!
According to the wiki:
The player can dry themselves out faster by standing next to a fire. The rate of wetness can also be decreased, but not stopped, by standing under a Tree (including Birchnut Trees). This will decrease the amount of time waiting to lose the 'Wet' status. Standing under a Tree grants 40% Water Resistance.
The best way to keep wetness low during Spring is to wear some Water Resistant gear. These items decrease the rate at which the player gets wet, and having more than one of them equipped provides a cumulative bonus. The character stops getting wet when 100% water resistance is achieved, so the player will want to wear a combination of them that doesn't surpass 100% by too much. When 100% water resistance is achieved, any wetness previously had will start to lower until the player becomes completely dry.
The Umbrella can't stop the rate at which the player gains Wetness, it will be slowed down because its water resistance factor is 90%.