[pmulcahy11b]

For weather, I use the system (originally made for AD&D) from an old issue of Dragon magazine (somewhere around issue 100, IIRC). It's very detailed, accounts for things like altitude, terrain, and even exotic weather like tornadoes and hurricanes and earthquakes (and things you don't need for T2K, like the activity of Wizards and Clerics and magical creatures in the vicinity). It generates temperature, humidity, wind speed, and the effects of things like the temperature/humidity index and the effects of extreme cold. A few conversions and voila!