This workflow uses Controlnet ip2p to generate weather changes. It's very traditional but simple and easy to use.

You can find the model by searching for "p2p" in install models of ComfyUI Manager. After installing it, select your favorite SD1.5 model from Civitai, and then use this workflow to change the weather in the picture.

The latest version using BNKTiled+SUPIR has been updated, which can have more kinds of graphic details. If you want a result closer to the original image, you can replace the Tiled Ksampler with a normal Ksampler.

There are several kinds of weather that will change randomly in the workflow. If you only want one kind, you can also keep only the weather you want and generate images.