Your tail lights are probably off
Daytime running lights leave the back of your car dark, and nothing inside tells you. In rain, that is the half other drivers need to see.
From drivers arguing about lights over a decade, with the legal and technical parts checked outside the conversation — including the rule change that explains why the problem exists at all.
There is a good chance that right now, in daylight rain, your car is lit at the front and completely dark at the back — and that nothing on your dashboard is telling you so.
Daytime running lights come on by themselves, so the front of the car glows and the instruments are lit and every cue available to you says the lights are on. They are not. Daytime running lights generally do not turn on your tail lights.
Which means the driver behind you, looking through a wet windscreen and a wall of spray, is looking for two red lights and finding nothing.
If the wipers are on, turn the headlights on — the switch, properly, not auto and not the running lights.
This is not you being told off for being careless. It is a rule about how the lights are built. Federal lighting standards used to require tail lamps to be lit whenever the headlamps were, and that requirement was amended in 1993 so that tail lamps need not come on when the headlamps are running at less than full intensity — which is exactly what a daytime running light is. So a dark rear on a lit car is not a fault and it is not a cheap car. It is the design working as permitted.
In many US states, wipers-on-means-lights-on is written into law outright. Not every state has it in those words, but where it is not spelled out the general low-visibility requirement usually reaches the same place. Your own state is the one that matters, and it is worth five minutes of looking up. The safety reason holds everywhere regardless of what your state wrote down.
The reason it is not about you
The instinct that gets this wrong is a reasonable one: you look out of the windscreen, you can see perfectly well, and you conclude you do not need the lights.
But your headlights in rain are not primarily for your benefit. They are how the other cars find you. In heavy rain, or spray off a lorry, or the flat grey light before a storm, a car without lights does not read as a car — it reads as more grey, until it is close. The person who needs your lights on is not you.
That is also why the tail lights are the half people forget: your own headlights are the ones you can see working, and the lights doing the other job are behind you where you never look.
The other switch
The opposite mistake is worth the same minute.
High beams do not help in fog or heavy rain and usually make things worse: the light hits the water in the air and bounces straight back at you, so you get a bright wall instead of a longer view. Low beams, aimed down, are what cut under it. Same for a lit city street — brights there do nothing for you and a great deal to everybody coming the other way.
And if you have raised your vehicle — a lift kit, bigger tyres, anything that changes how it sits — your low beams are now pointing where your high beams used to. That is not a metaphor; it is the same lamp aimed higher. People described being blinded by oncoming vehicles that had been raised. Whether the driver knew is a separate question, and one person put the generous reading on it: you cannot see your own beam pattern from the driver’s seat, so it is a thing that is easy not to know. If that is your car, the lights need re-aiming, and it is a small job.
One honest gap, and it is a large one given what this page is called: none of this covers the driving itself. Nothing here is about braking distance, standing water, tyres, or what to do when the back of the car goes light. Those are real questions and they are not answered here. There is also a reader for whom none of this applies, and it is worth checking whether you are them before you change a habit. Some cars switch the full lights on by themselves in low light, tail lamps included, and if yours is one of them there is nothing here for you to do. The only way to know is the walk-behind check above. Assuming your car does it, and assuming it does not, are the same size of mistake in opposite directions.
What is answered here is the part you can settle in the next minute, from a parked car, for free — which is whether anybody can see you at all.
Full tip: https://findangel.org/tips/your-tail-lights-are-probably-off · FindAngel.org — free, always.