Nice write-up on building a cheap weather station with the Raspberry Pi as the brains. You can even use the cheaper Model A (or new variant of it) to save some on costs. Would be nice if it was converted to alternative power source too.
http://www.instructables.com/id/Complete-DIY-Raspberry-Pi-Weather-Station-with-Sof/
Update:
found one http://www.instructables.com/id/Raspberry-Pi-Solar-Weather-Station/