“comparatively hot“ vs “comparatively hotter”

Which is grammatically correct? Is it best if the adjective is left unchanged i.e. ‘hot’?

The weather is comparatively hot today.
The weather is comparatively hotter today.

Also, should a comparative adjective have a second clause introduced by "than"?

The weather is comparatively hot/hotter than yesterday.

no meaning gets added to "hot" or "hotter" by adding "comparatively". the redundancy is obvious in the case of "hotter" but even "hot" includes an implied comparison to something.