And again snow..

Snow again...

We all have thought summer has come, aren't we?

We all thought summer had come, didn't we?

But no such luck. Snow fell again.

(Awesome.  I would probably have put an ellipsis between the two sentences, but that is just a style choice. But no such luck... snow fell again.)

Somewhere someone's walking in shorts, but you should put on a warm jacket and hat.

(I think there maybe should be a comma after somewhere: Somewhere, someone's walking..., but I'm not actually sure - punctuation can be hard even for native speakers haha.  This sentence is very good though.  You could try also: Maybe, somewhere, someone's walking in shorts, but you should put on a warm jacket and hat.  This is saying that while it may be warm somewhere else, right here it is cold so you should dress up.)

Where are you, a hot sun?

Where are you, hot sun?

I hope that summer hears your call and comes soon!