I once rolled up two weeks worth of weather using the tables in the Greyhawk Gazette. Gawd help us, never again. These days I use the highly scientific method of looking out of the window. :D
I actually contend that trying to use the WSG weather tables scrupulously caused the destruction of my college D&D game. Note that for all that effort, you get one of those letter temperature indicators -- and it has no in-game effect whatsoever, it's just purely descriptive flavor-text.
Wow, thanks for the comments. Mixing real life and AtoZ is nearly killing me, that's why this post was so abrupt. I don't like the WSG. What I am trying to work out is it just me, grumpy overworked middle aged, or is it the book?