It's surprising to see how much green weeds are surviving even though it's evident that there hasn't been any rain for a while

This soil is heavy clay and stores the water well. If there was more sand, it would be dry all the way down.

when is the rainy season going to be?

I am in Northern Germany.
Rainy/Dry season only happens close to the equator. In Nigeria, Brazil, Thailand... such places.

Up here, we got winter and summer. Right now it's very late spring.
Summer is warm and has long days. Winter is so cold, the rain falls down as snow.

Typically, it rains every 1-2 weeks.
Usually we have too much rain even during summer.