Check out poncho.is which launched recently from betaworks. They do this (It's warmer than yesterday) and it's been really helpful for the confused nyc seasons we're getting.
I'm in NYC area and love this service. Signed up in April, have been wanting to recommend it to friends, but until this morning's update with a URL in it, I couldn't remember what service it was and the SMS "HELP" didn't tell me.
If Poncho is reading this, update your HELP to mention poncho.is!
If Poncho is reading this, update your HELP to mention poncho.is!