The problem is probably on the Yahoo end.
My application broke too. I have temporarily fixed the problem by replacing weather.yahooapis.com to weather-ydn-yql.media.yahoo.com. The endpoint URL which was exposed previously is down today, I found alternative working URL through some google searches (apparently it seems they have updated their android mobile app yesterday which may have broken this, don't know guessing this based on google search results).
Anyhow, Yahoo weather developer document now recommends not to use weather.yahooapis.com and use instead YQL
You can use below URL for as per YQL recommendation instead of
Old URL
http://weather.yahooapis.com/forecastrss?w=2502265
New recommended URL
https://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20weather.forecast%20where%20woeid%3D2502265
Here, parameter w is WOEID.