Question

We did not have a good time at the picnic as it was too hot.(Begin with but)

Answer 1

But it was too hot and we did not have a good time at the picnic.

I hope it's correct

Answer 2

But it was too hot; we did not have a good time at the picnic is the correct answer.

When the sentence mainly talks about the quantities which are more or less than enough and we use too much, too many, too few and too little before a noun.

It is common to use or add emphasis to an adjective or an adverb, but it does not mean the same as too.