Weatherlore

Weatherlore is a skill that, when used, gives you a general idea of the weather conditions and climate, as well as a guess as to the chances of whether or not it will rain. This is useful for preparing your clothing for hot or cold climates. To use it, press Alt+w (v315).

Generally it's not seen as being very useful, although using it once happens to take exactly the right time for some meat/fish to cook.

Previous versions
Prior to version 3.16 it was not possible to improve this skill by using it.