actually, they sound pretty much the same, "weather" and "whether" these kinds of words that sound alike but have different meanings and spellings are called 'homonyms' I hope this helped :)

There is no difference.

I agree with Randy as there is absolutely no difference in how they sound. As Shannyboo said, the words are homonyms. The spelling and meaning is different; the sound is the same.

Weather- we-THer Whether- hWe-THer The TH sounds like "d". If you have noticed, Both are somehow pronounced similarly but with "whether" a little emphasis with the "h" sound is present before "w".