This is not a rant. OK, it's sort-of a rant, but actually it's an attempt to turn a rant to productive use. In the interests of improving the general level of rain driving skills in Southern California, please consider a few thoughts from someone who's lived in places where serious, heavy rain is a regular occurrence.
1. Use your headlights. Seriously, it's not about you being able to see. It's about other people being able to see you and not run into you. By turning on your headlights, you're also turning on your tail lights, side lights, and all the other things that make your car a mobile Christmas tree, improving the chances that traffic coming your way will stop in time.
2 Be predictable. This is basic defensive driving stuff. The people around you may be hydroplaning, might have fogged up windshields, or might be totally freaking out because there's precipitation falling from the heavens. Use your turn signal when you change lanes. Don't weave. Don't make quick lane changes except in an emergency. Basically, pretend you're surrounded by a bunch of jumpy, freaked-out psychotics armed with two ton chunks of plastic and steel and don't do anything to startle them.
3. Drive in the wheel marks of the car in front of you. The wheels of the car in front of you are doing a bang-up job of clearing water off the roads. You can see those wheel marks on a wet road as a somewhat more dryish patch. The tires throw the water to the sides, and then the water gradually flows back where it was before. That means that, for a window of time, there's a somewhat more dry patch of road. By driving in that dry-ish patch, you reduce your chances of hydroplaning.
4. Drive towards the middle of the road. Most of the big puddles will be towards the edges of the road, because that's how we slope roads. Drive towards the middle to avoid them.
5. Allow extra stopping distance. Your brakes don't work as well when they're wet. And even if they do, your tires have less friction on a wet road. And even if they work well, you might find out, at the wrong time, that you're hydroplaning. Allow yourself some extra stopping distance.
6. Try not to hit the brakes in the middle of a curve. In a curve, your tires are already doing what they can to hold your car on the road. Hitting the brakes might be just what it takes to get them sliding instead of gripping. Try to slow down before you get to the curve. Once you're in it, if you need to slow down further, take your foot off the gas and coast. Use the brakes in the curve as a last resort.
7. If you're hydroplaning, try not to steer or brake. If you're hydroplaning, your car wants to go straight ahead. Your front tires aren't gripping well, if at all, so steering can send you into a spin. The best thing to do, if the road and traffic will allow it, is to take your foot off the gas and coast till the wheels grip again. (The faster the car, the more likley it is to hydroplane. By slowing down, you give the water more time to get out from under the tires, so the tires can grip the road again.) If you have antilock brakes, they should still work to slow the car, but not as well as on a dry road--see "allow extra stopping distance" above. If you don't have ABS, and you have to use the brakes, use them with caution and remember that you might have to pump them. Sometimes you'll hit a large puddle on only one side of the car. That'll tend to pull the car in the direction of the puddle, because of the friction from the water. Correct as you would for any other skid, steering away from the puddle to keep the car moving straight ahead.
Driving in Flood Waters
And now a word for the aspiring Captain Nemos out there--and I count myself a proud member of your ranks.
First off, let's talk about why driving in flood waters is usually a bad idea.
If it's not a bad flood, your car's likely to be hydroplaning a good bit of the time. Also, you can get water up the tailpipe, which will toast the engine pretty darn quickly. As you drive forward through the flood, a bow wave will build up ahead of the car, and water will start sloshing through the engine compartment. That sloshing water can short out the ignition wires, stalling the engine. Also, a car's door seals are designed to keep out rain, not flood water, so she'll start taking on water, which means, at a minimum, you're going to have to replace the jute that glues the carpet to the floor, you'll need to worry about rust, and you might soak the computer (which is often on the floor under one of the font seats).
If it's a bad flood, the tires might leave the road surface. A car will float, at least for a few minutes. During that time, the front wheels become rudders and the drive wheels act like paddle wheels, but minus the paddles. Congratulations, skipper: your vessel will doggy paddle along at maybe 5 miles per hour until she stalls, sinks, or gets swept away by the current to a nasty fate somewhere downstream.
So, it's usually a bad idea to drive through flood waters. However, if you should find yourself in this situation, here are a few things to keep in mind.
1. Consider whether bailing out is the better answer. If the car's in danger of getting swept away, you mght be better off abandoning it. After all, chances are good you can swim better than a car can.
OK, Cap'n Nemo, you've decided to hang with the car. Let's talk about driving in this new environment.
2. Downshift. You need to keep water out of the tailpipe, which means you need to keep lots of exhaust bubbling out. Hybrid drivers (and I'm one) don't have a lot of choices at this point, but folks with non-hybrids should downshift (that's "L1" if you're in an automatic) to keep the engine revved up.
3. Watch the speed. The last thing you want to do is slosh water up onto the ignition cables and stall the engine, because then water gets into the tailpipe and it's all over. (As an aside, if you do stall it, but you manage to coast to a dry-ish area, drying off the ignition cables may be all you need to do to get it started again.)
4. If the wheels leave the road, don't panic. You'll feel it if it happens. Keep the engine revved up and doggy paddle to the nearest relatively dry area. Remember, though, not to rev too much because once those wheels grab again, you don't want the car to suddenly launch itself into something. Once you're back on solid ground, make an appointment with your mechanic, cause you'll probably need it.
You can find more rain driving tips here.