Погода ("Pa-go-dah" -weather)

I do not understand the weather in St Petersburg.  It has been cold and snowy all week, and it seems to get colder around noon, and then warm up again in the afternoon/evening.

How can this be?

I assumed it couldn't, and that it was all in my head... When I went outside at noon and it seemed colder, I was simply feeling the cold all the more after being in a comparatively warm classroom setting.  Then, in the evening, it seemed warmer because I had been running around in my coat all afternoon.

But I discussed it with two other students, and they agreed with me-it seems to get colder in the early afternoon, and warmer in the evening.

Today when I woke up (at 8am, before the sun came out) it was raining.  By noon, the dreadful rain had turned into the biggest, most beautifully fluffy snowflakes you've ever seen.  By evening, it was raining again.

What's up with that?