This is a more general version of the #uksnow map idea. It's a crowd-sourced weather map which relies on the fact that any one individual tweet about the weather might be inaccurate but given a large enough sample, enough people will mention the weather in their area to make this a workable idea. It doesn't require people to tweet in a particular format.

To get info

Have an array of weather words in various languages (rain, hail, snow, schnee, ame, yuki)
every 5 minutes:
	foreach weatherword
		search twitter for that word
		retrieve latest 100 tweets
			get user info
			get user.location if available
				username, time, lat, long, geotude, weatherword
		Remove any tweets about this weatherword older than 6 hours.

To display info

Show a Google map
Based on current Zoom level, split the current map into about 100 geotudes
foreach geotude
	search database for any weather results for that block (probably using an ilike "1234%" on the geotude field)
	sort by weatherword count descending
	draw an icon on top of that block to show the most common weatherword
If the user zooms in, recalculate geotudes and repeat.

I quite like that this uses geotudes which I think are an excellent idea.