I ride every day. Heat, rain, snow. Just clothe accordingly, pack change of clothes in waterproof bags/panniers and go.

When it is colder than 15 degreee celsious AND raining - it is unpleasant. That's it. Everything else feels nice, pleasant.

Of course, I prefer 20 - 25 degrees, sunny, but that doesn't happen always and rain is really not BAD. Just in your head - if you make peace with getting wet (and changing to dry clothes) it is OK. Bit more work changing clothes, but no big deal.