At my parent’s house in Ventura, CA, the Santa Ana winds can reach above 74 mph, and we were discussing if they should use their fireplace during this time. So, we did some digging. Here’s what we found.
Fireplaces shouldn’t be used during high or extreme wind (above 40 mph). Doing so could pose a danger by trapping smoke inside or spreading embers from either the top or bottom of the chimney. When wind speeds are low to moderate (below 40 mph), using a fireplace shouldn’t lead to any issues.
So you can typically use a fireplace as long as wind speeds are below 40 mph, but is it still safe to do so? Also, how can you increase the wind resistance of your fireplace?
Let’s take a closer look.
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Is it Safe to Use a Fireplace When It’s Windy?
As long as you take good care of your fireplace to prevent creosote residue buildup, cracks, and water damage, it is typically safe to use your fireplace when wind speeds are less than 40 miles per hour. However, be sure to watch for downdrafts or an increase in wind or storm severity, as these can become dangerous.
Since fireplaces are fairly sheltered indoors, you can start a fire in some conditions which would be considered unsafe if you were outside. The fire should be well covered by heat-proof material, and only the smoke, not embers, should be rising out of the chimney.
Please note that outside fires such as campfires or patio fire pits should never be started if it is windy, as the wind might catch some of the embers and scatter them around. This could start nearby fires in your surrounding environment.
Here are a few things to watch out for to avoid potential dangers if you are using your fireplace under windy conditions:
- Downdrafts. These occur when fire elements like smoke, gas, or embers that should be rising out of the chimney are being pushed back inside your home.
- Storm Severity. If your area is receiving severe storm warnings or intense crosswinds, you should probably put out any fires in the fireplace and avoid using it until the storm or strong winds have passed.
To check if downdrafts will happen before starting the fireplace, you can light a match inside and watch which direction the smoke goes. If it travels upward, there shouldn’t be a downdraft.
Also, yearly maintenance checks on your fireplace will prevent creosote buildup, cracks, and water damage before strong winds can worsen them.
Will Wind Cause a Chimney Downdraft?
Strong winds that exceed 40 miles per hour are capable of causing chimney downdrafts. Less severe winds do not cause downdrafts. If smoke, embers, or gases are being pushed into your home while the winds are not strong, your chimney may have structural issues or blockage.
Downdrafts are dangerous because they force the harmful elements that fires produce into the enclosed space of your home. These elements include gasses like carbon dioxide and carbon monoxide.
Fireplaces and their chimneys are supposed to let these gasses and other elements rise passively up and out of your home. If your fireplace has structural issues or blockages, its ventilation might have issues and downdrafts may occur.
If your fireplace has been checked by a professional and you are still getting downdrafts, it could be caused by wind gusts pushing the smoke back down. Very high crosswinds can also alter the air pressure, trapping the smoke and less visible elements to force them back down.
When is it Too Windy to Have a Fire in the Fireplace?
The National Weather Service defines high wind speed levels as 40 to 57 mph and extreme wind speed levels as anything greater than 58 mph. Whenever wind speeds range from high to extreme in your area, you should not have a fire going in your fireplace.
If you live in an area with tornadoes or gale-force winds like tropical storms or hurricanes, it is best not to start a fire during those events. Downdrafts can happen even if the wind is not very strong. They depend more on the angle that the wind is entering your chimney. Always use your best judgment when deciding to start a fire.
Tips for Fireplaces During High Winds
Although wind is often responsible for spreading around embers that could ignite if they land outside of the fireproof zones in your fireplace, you can mitigate this effect. You can increase the wind resistance of your home fire system in some of the following ways.
Add a Chimney Cowl
A chimney cowl is a cap that you can install at the top of your chimney that has a few different helpful functions.
Installing a chimney cowl does all of the following beneficial things:
- Blocks wind from entering the chimney
- Keep animals and birds out, as well as nesting debris
- Keep large particles and embers inside the chimney
- Increase and influence positive airflow
- Prevent water from entering the chimney
- Makes your fireplace more energy efficient
Chimney cowls are also more efficient than chimney caps, so they’re starting to become more popular as well.
Move Branches Away from the Chimney
Moving branches away from the chimney does not necessarily prevent wind from getting to the chimney, but it will make your chimney a safer space.
If embers do make it out through the chimney, and there are no branches nearby for them to land on, it’s less likely they’ll cause a fire.
For this same reason, you should also keep your roof free of debris and keep your gutters cleaned out if you are using your fireplace. If a fire starts in a patch of leaves on a windy day, it can easily be blown around, spreading the fire.
So, my parents now know that they shouldn’t be using their fireplace during the Santa Ana winds as any wind over 40 mph can create unsafe conditions for fireplaces. While this only means a few days out of the year, it’s good to know for best fireplace safety.
Remember to get your chimney inspected yearly, check for any downdrafts, and consider upgrading your chimney cap to a cowl for better wind resistance.