Can a Lawn Mower Be Left Out In The Rain?

Have you ever thought about leaving your lawn mower out in the rain? What about using your lawn mower soon after heavy rain?

It turns out lawn mowers can be left in the rain for short periods. You can finish mowing the lawn when surprised by rain and a sudden bad weather change. It’s not indicated to leave the lawn mower out in the rain to avoid start problems and premature rust.

Some of the best lawn mower engines are designed to withstand heavy rain. Properly sealed, they suffer minimum to no water damage when exposed to rain for just a few minutes. A lawn mower left in the rain for a whole day might face starting problems, mainly due to wet spark plugs and water in the carburetor.

Lawn mowers are now better designed to last a long time. For example, Briggs and Stratton and Kawasaki lawn mowers are frequently sold with 3-year warranties. Even more, there’s a 5-year warranty on Honda lawn mowers.

This means these machines are powerful and long-lasting. Typical lawn mower problems involve the following.

  • Not using the lawn mower correctly
  • Not changing oils and filters
  • Leaving the lawn mower out in the rain

A lawn mower can suffer technical faults when left out in the rain even if it starts. For example, high humidity favors rust. This is a long-term problem that isn’t immediately visible. Lawn mower engines can also work in ‘hiccups’ as a result of water making its way in the carburetor.

What can happen if you leave your lawn mower out in the rain?

If you forget your lawn mower out in the rain you can face engine problems such as water getting into the carburetor or lawn mower body problems such as rust. Here are the most common problems of lawn mowers left out in the rain.

Water can get inside the gas tank

Most lawn mowers have a gas tank cap that sits on the lawn mower at all times. If you forget to close this cap and you leave the lawn mower out in the rainwater will make its way into the gas compartment.

You should not try to start a lawn mower you believe has water in its gas tank. Its gas tank needs to be emptied and left to dry for at least a couple of days, preferably in the sun. You will then add new gas to the tank and try to start the lawn mower.

Rainwater can damage spark plugs and lawn mower ignition

Electrical components of the lawn mower tend to be the most affected by water leaks or heavy rain. Wet spark plugs fall to create a spark. If your lawn mower has been sitting out in the rain for a long period, chances are its spark plugs are wet.

You can try to start the lawn mower a few times when the spark plugs are wet. In most cases, you will need new spark plugs or simply wait to see if the lawn mower starts when the spark plugs are completely dry.

Lawn mower carburetors can be affected

Lawn mower carburetors are essential for the combustion of the engine. Essentially, lawn mower carburetors are engine parts responsible for mixing fuel and air to ignite combustion.

The water inside the carburetor is a common problem for lawn mowers left out in the rain for weeks and months. Even debris and dust can cause a lawn mower carburetor malfunction. However, water inside the carburetor is a sign you need to clean it yourself or to have it serviced by a professional.

Rain can rust the engine and the lawn mower

One of the biggest problems of lawn mowers left out in the rain is rust. On some level, rust seems inevitable even for lawn mowers that are stored in the garage or the shed. However, water makes this process faster.

You should always try to keep your lawn mower dry to avoid rust problems. A rusty lawn mower has wheels that don’t move easily. Its pull-engine ignition starts to work badly as well. Furthermore, rust can eventually ruin the start of the lawn mower, its blade, its wheels, and its chassis.

You want to avoid touching rust yourself. Cutting yourself in a rusty piece of metal can lead to infections. This is why you want to keep your lawn mower rust-free.

Rain favors mold growth inside your lawn mower

Another common problem caused by excessive water exposure is mold formation. A lawn mower that has been left out in the rain and not dried properly will start to grow mold, even if it isn’t visible at first.

Mold in the lawn mower can eventually trigger issues such as an engine that isn’t starting. Even more, mold is not healthy as you might breathe it in as you walk behind your lawn mower.

Can I use the lawn mower after the rain when the grass is still wet?

You should not use a lawn mower on wet grass or a wet lawn. This will make mowing inefficient and it might even ruin the look of your lawn. Wet rain is cut in patches as grass tends to stick to the blade. Here are a few common issues you can recognize when mowing wet grass soon after raining.

  • Grass clumps

Some grass clumps will be visible after you pass with the lawn mower. This is caused by wet grass sticking to the blade of the lawn mower. Furthermore, it can be one of the most common problems that can be avoided by simply mowing dry grass.

  • A dull blade

Wet grass tends to dull the blade faster. If you notice your blade isn’t performing as well as it once did it’s a sign you either need to sharpen it or replace it. Wet grass is one of the common causes of premature lawn mower blade dulling.

Can I leave an electric lawn mower out in the rain?

Electric lawn mowers are made to resist mild water exposure. These lawn mowers don’t break when exposed to rain for a short period as sealing protects water from getting to its internal components. It’s only exposed water contact that can ruin these lawn mowers.

Electrical lawn mowers are a bit more prone to condensation and water damage issues compared to combustion-based lawn mowers or gas lawn mowers. You can expect to encounter one of the following issues with an electric lawn mower left outside.

  • Corroded battery connectors

Batteries are protected by an external plastic layer or shield. It’s unlikely water can make its way inside the battery. However, the battery can sometimes make its way to the battery connectors. These can corrode and eventually stop the power transfer from the battery to the lawn mower.

Corroded battery connectors are also seen on lawn mowers stored outside. Your lawn mower can suffer from this issue even if safe from the rain and simply stored outdoors. Quick temperature fluctuation typically comes with instant condensation. Repeated condensation can lead to premature corrosion in battery connections for electric lawn mowers.

  • Short circuits

Short circuits are rare on electric lawn mowers due to their internal proteciton systems. However, you should not start an electric lawn mower that isn’t completely dry. You need to ensure all of its parts are completely dry after it has been out in the rain to avoid immediate short circuits and possibly electrocuting yourself.

Some lawn mowers are plugged in an extension power cord. Others run on batteries. Both can be subject to short circuits when exposed to water or high levels of condensation.

  • Electrocution

Electrocution is the ultimate problem with leaving the electric lawn mower out in the rain. A short circuit can damage its electronic components. Electrocution impacts the user. This is why electric lawn mowers should be stored indoors where they’re sheltered from the rain and extreme temperature changes.

How to store your lawn mower outside

In theory, there are methods you can use to store a lawn mower outside. This should only be an option if there’s no place to store your existing lawn mower. There are small storage differences between gas-powered lawn mowers and electric lawn mowers.

  • You can store a combustion lawn mower outside using a cover

A tarp or a lawn mower cover is crucial when storing your mowing machine outdoors. A push lawn mower cover is easy to put on the machine. Storing riding lawn mowers outdoors requires a larger tarp, on the other hand.

The idea is to protect the engine and other parts of the lawn mower from the rain, wind, and even from excessive direct sun exposure. This will only be a short-term option, as you can imagine.

All of the components of lawn mowers can suffer when stored outdoors in cold weather, particularly in the winter. This is the sole reason you should look at either investing in a shed or looking for a place to store your lawn mower. Even hanging a lawn mower off a wall can be a good solution for homes with limited storage options.

  • You can store an electric lawn mower outside by removing its battery

Electric lawn mowers are less likely to be stored outdoors. To avoid rain damage you should always remove the batteries of your electric battery lawn mower stored outdoors. Other electric mowers should always be unplugged when stored outdoors.

Still, you need to add a cover on top of the lawn mower to avoid further water damages. Lifting it above ground level is also recommended, especially when it comes to good ventilation which keeps condensation, rust, and molds away.

How to start a lawn mower that’s been out in the rain

You can start a lawn mower after it has been sitting in the rain to let it run on the ideal. Heat dissipation from the engine will evaporate excess water from the mower. Here’s what to do if the grass cutter doesn’t start

Change gas

The water inside gas makes the lawn mower unusable. Water prevents the spark formation which starts the engine. This is why one of the first things to do when it comes to your lawn mower that doesn’t start after being left outside is to change gas.

You can tip over the lawn mower to eliminate old gas and then let the cap open for a few hours for its gas tank to dry completely. Once fresh gas has been added you can try and start the mower again.

Change the spark plug

Wet spark plugs don’t produce a spark. You need to check all of the spark plugs of your lawn mower (mainly just one in most cases) to see if they work properly. You can dry them with a paper towel. Sandpaper is then used on its contacts for deep cleaning.

Check air filters

Wet air filters can limit the amount of air that gets inside the engine and prevent combustion. Wet air filters can be dried with a hairdryer. Most lawn mowers require no tools to remove the air filters. This filter is normally located on top of the engine to the left or the right side.

Check battery health

If your lawn mower is electric and it doesn’t start you should check its battery health status. This means its battery needs to be tested first. Alternatively, you can try to re-charge the battery (only when completely dry) to regenerate its power source.


Leaving your lawn mower out in the rain is not recommended. Still, there should be no major mower damage when it’s in contact with water for a short period. Some people continue mowing in the rain but at a slower pace.

Problems arise with constant rain or water exposure. Water can infiltrate parts of the engine making the lawn mower unusable. Water can also hurt the battery when you’re operating a battery-powered electric lawn mower.

If you encounter starting problems that have been left out in the rain you need to change gas, clean or replace the spark plug, dry the air filter, and possibly clean the carburetor. Your lawn mower should start after completing all of these steps.