Jump starting in the rain: is it safe, and what to do differently

Is it safe?

Generally yes. A car's electrical system runs at 12 volts, which is not enough to push a shock through your skin the way household current can, wet or dry. The real hazards in a jump start are sparks and short circuits, when a clamp touches the other clamp or the wrong piece of metal. A battery also gives off hydrogen gas that a spark can ignite. Rain doesn't remove those hazards, and it can make them harder to see.

A light or steady rain is not a problem. Water pooling in the engine bay, or running across a fuse box where a jump terminal sits, is a reason to wait for the rain to ease or to find cover first.

What to do differently in the rain

The steps are the same. These are the extra things that matter when it is wet:

• Wipe the top of the battery and the terminals with a dry rag before you connect anything.
• Keep the cable ends and the clamps out of puddles. Don't let a clamp rest in standing water.
• Keep the clamps from touching each other. Wet, slippery clamps are easier to drop.
• Wear gloves, since cold, wet hands lose their grip on metal.
• Keep the hood open only as long as you need it.

The connection order doesn't change

Red clamp to the dead battery's positive post, the other red clamp to the good battery's positive post, black to the good battery's negative post, and the last black clamp to bare, unpainted metal on the dead car, away from the battery. That last connection is where a small spark is most likely, which is why it goes away from the battery.

Wet clamps can be slick enough to slip off a post. Give each one a firm wiggle after you attach it, so it has bitten into the metal, and keep the cable ends from resting against the hood or a fender. When the car starts, take the cables off in the reverse order, starting with the black clamp on the bare metal, and don't let the clamps touch as they come off.

When to wait instead

Some conditions are reasons to hold off, rain or not:

• Lightning nearby. Wait it out in a closed car instead of standing under an open hood.
• Standing water. If water has been over the floorboards or into the engine, don't try to start or jump the car. Water pulled into an engine can wreck it when it cranks over.
• A cracked, swollen or leaking battery. That one shouldn't be jumped in any weather.

If you'd rather not do it in the rain

You don't have to. A jump start is $49–$75, plus the $19 dispatch fee, which covers sending the driver to you. We text or call when the driver is on the way. On average a driver arrives in 30 minutes, though the actual time depends on your location and traffic. Wait in the car with the hazard lights on if you are somewhere that isn't safe to stand. Mention the rain when you request help, so the driver knows what to expect when they get there.