1) Sunrise/sunset times
I like to get up before dawn to hike because some of my best wildlife encounters have been just before or just after the sun comes up. Sunset provides similar opportunities.
2) Moonrise/moonset times
When I’m in the mood to stare at the stars it helps to know if the light from a full moon is going to spoil the view. On the other hand a little moonlight can really help visibility on a pre-dawn hike.
3) Average high/low temperatures
4) Average precipitation
When planning a trip two or more weeks ahead of time, it helps to know what the *expected* temperature and precipitation will be, especially if camping.
5) Forecast high/low temperatures
6) Forecast precipitation
As a trip date approaches it helps to know the forecast so you can adapt to last-minute conditions.
7) Local flora and fauna
I like to know what plants and animals I can find, where I can find them, when I can find them, etc.
And when I’m near a coast, 8) Tidal phases
Along the shore this is crucial when I want to tidepool for marine critters.