http://revach.net/article.php?id=2626

Section: Halacha   Category: Tshuvos
Shevet HaKehosi: Forecasting The Weather
 The Rema paskens in Yoreh Dei'ah (179:1) that one should not look at the stars to find out the future because the Torah says "Tamim Tihiyeh Im Hashem Elokecha" (Devarim 18:13) one should go innocently with Hashem.  What about listening to tomorrow's weather forecast?  Is that considered predicting the future?
 
The Shevet HaKehosi (2:322) says that listening to the forecast is permissible and not an issur of Tamim Tihiyeh.  The reason is that the weather is predicted based on conditions present in the atmosphere right now.  It is similar to looking up and seeing thick dark clouds and "predicting" that it will rain shortly.  The only difference is that the meteorologists use more sophisticated tools and examine a wide array of current conditions.
 
He brings a Raya from Yuma (21a) that says that on the last day of Succos they would look at the smoke rising from the Mizbei'ach.  Based on its direction they would know what the overall rainy season will be like that winter.  We see from here that predicting the weather is not assur.
 
Important Note: We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. Please also understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.