You are welcome to answer questions posted in the Ask a Teacher forum as long as your suggestions, help, and advice reflect a good understanding of the English language. If you are not a teacher, you will need to state that clearly at the top of your post. Please note, all posts are moderated by our in-house language experts, so make sure your suggestions, help, and advice house the kind of information an international language teacher would offer. If not, and your posts do not contribute to the topic in a positive way, they will be subject to deletion.
Both of these sentences are grammatically accurate.
There's a very slight difference between these sentences - If you say 'I thought it was going to rain' then it's because there was some evidence to make you think this. Maybe the sky was black...
In the second form, 'I thought it would rain...' there wasn't any visible evidence to make you think this - you just thought that it was possible or likely.
But the difference is very small here for reported speech!
would/ was going to 
Linear Mode
