Geographically, put a cold-proof sign on clothes.

Symbol A means rainstorm, so it is necessary to prepare for flood prevention and early warning.

The b symbol means sunny day, and it doesn't need to add clothes to prevent cold, which doesn't meet the meaning of the question;

C symbol means snowfall, so it is not necessary to do anti-freezing work on wheat, which does not meet the meaning of the question;

The d symbol means thunderstorm, and there is no sunshine, so we can't do solar power generation experiments, so it doesn't meet the question.

So choose: a.