Original description:
Small puddles on the ground like in GTA VC
This modification was made to achieve a greater effect on wet asphalt (together with Road Reflections Fix). With it, when it rains (after a while), small circles and splashes will appear on the ground, just like in previous games in the series. They are almost invisible on screenshots; it is better to see them in person.

Drops of rain and blood on the screen like in GTA VC
Now, in rainy weather, drops will appear on the screen. Their behavior is copied from their behavior in GTA VC: they "twitch" and slowly flow down and disappear when the weather becomes clear or the player enters a building.

(Updated version by ArtemQa146)
Two old but cool mods from TrushinVlad, which I updated a few months ago and published on my discord, are now published here, with the permission of the author, of course.

List of changes:

Small puddles on the ground like in GTA VC

Previously this worked by detecting the weather, but the rain starts before the game sets the weather to "rainy". And also the rain ends before the weather changes to the game;
Now the intensity/number of puddles depends on the intensity of the rain. Previously there was only one intensity;
Puddles appear where the camera is looking. Previously, puddles appeared only around the main character, because of this, when the camera moved away from the player, there were no puddles;
Puddles appear more naturally with a slight delay between them. Previously they appeared all at once every 500ms;
Maximum intensity/number of puddles doubled. Achievable only at maximum rain level;
The textures of the effects were slightly edited, the too white parts of the image were slightly darkened, which is why now the fall of the drops is not very noticeable;
The radius of scattering of puddles has been increased;

Drops of rain and blood on the screen like in GTA VC

Fixed a bug when the script gave too large a value for the timer, which is why the drops almost never appeared (Only when restarting the game);
The visibility of the drops has been reduced, now they are not noticeable, and the transparency setting has been added to the .ini file;
Raindrops now depend on rain intensity;
The speed of the player/player vehicle affects the behavior of the drops. The higher the speed, the faster the drops flow, and depending on the speed, they can slightly change their direction to the side;
Textures optimized. The textures themselves now have DXT3 compression (as is necessary for such textures), and are also unloaded from the script without clogging up memory.