Gloomy /ˈɡluːmi/ nearly dark, or badly lit in a way that makes you feel sad. Depressing. E.g. A gloomy room/atmosphere. It was a wet and gloomy day.
Overcast: /ˌəʊvəˈkɑːst/ covered with clouds; dull. E.g. an overcast sky/ day. Today it will be dull and overcast.
Dull: (weather) not bright, with a lot of clouds. Overcast. E.g. It was a dull, grey day.
Gale: an extremely strong wind. E.g. The gale blew down hundreds of trees. Gale-force winds (British English) It's blowing a gale outside (= a strong wind is blowing).
The wind blows/ whistles/ howls/ picks up
The rain falls/ comes down (in buckets/ sheets)/ pours down. E.g The rain was coming down in sheets (= very heavily).
A storm is approaching/ is moving inland/ hits/ strikes/ rages
Thunder rolls/ rumbles/ sounds
Forecast/ expect/ predict rain/ snow/ a category-four hurricane
The weather improves:
The sun breaks through the clouds
The sky clears/ brightens (up)/ lightens (up)
The clouds part/ clear.
The rain stops/ lets up/ holds off
Let up to become less strong
hold off (of rain or a storm) to not start. E.g. The rain held off just long enough for us to have our picnic.
- The wind dies down
The storm passes.
- The mist/ fog lifts/ clears