WW2 pilots used to call it “going for a Burton”. That’s the situation where you are out of control, and you just have to wait to see whether the fates bring you a “wizard prang” or not. If you’ve been driving a while, you’ll probably know that feeling. If you haven’t, probably your driving instructor didn’t tell you about this.
When are you most likely to go out of control, and go for a Burton?
Most likely, it is not when it is pouring rain. At that stage, you have read the signs, have slowed down because of reduced visibility and slowing traffic, and are content just to tag along and keep the windscreen clear so you can “watch out!”
The time most likely is just after rain has started, particularly if it has been preceded by a long dry spell. The road surface micro-texture gets clogged with dirt, oil, and rubber dust. Combine this with a little bit of water, and it makes a superb lubricant. Your tyre may be in contact with the road, but the road surface isn’t showing any sharp gravel bits for the tyre to grip on- they are buried in slippery gunk! So you can spin your drive wheels, or slide dramatically, if you are heavy on the accelerator or steering. So, just as it starts to rain, back off. Wait for the rain to wash the road clean, and things will improve slightly.
The best grip then happens once the road is dry, and clean again.