Some outdoor cooling methods work better in certain types of weather than others.
Knowing a little about your weather and knowing a little about each cooling method (below) can help you choose which will work best in your area.
Look for average weather patterns in your area during the hottest months of the year. When it comes to choosing outdoor cooling, averages can be much more helpful in the long run than a daily forecast.
The most important things to look for are average air temperature and average relative humidity. Average wind speed and highest recorded temperatures can also be helpful.
These measurements can help you plan what kind, size, or configuration of outdoor cooling to buy. If you know the weather you can know in advance if an outdoor fan will provide enough cooling for your area. You’ll know if some kind of evaporative cooler, misting fan or misting system will provide any cooling at all. You can know in advance if outdoor shades would work better instead. You can know in advance how powerful a portable air conditioner you’ll need.
These measurements will also tell you when it’s hot enough to use some sort of outdoor cooling. Of course you can also tell by simply stepping outside. But you’ll probably want to already have your outdoor cooling in hand or set up before it gets that hot. If you know it usually gets hot in June, you might want to already have your outdoor cooling solution ready to use in April or May.
Weatherbase.com is a basic, informative weather site. It’s a great place to find out weather averages for many cities worldwide. Click here to go to Weatherbase.com. It will open in a new window.
Average air temperature.
The amount of outdoor cooling you can expect from any method is based in part on the air temperature. In other words each method will reduce that temperature, or your sense of that temperature, by a certain amount relative to the air temperature.
Average relative humidity.
Knowing the Relative Humidity (RH) for your area will tell you about how much cooling you can expect from methods that use evaporation. This includes misting systems, evaporative coolers ("swamp coolers"), and misting fans. The sense of cooling we get from outdoor fans and portable air conditioners is also influenced a little by humidity, but to a much smaller degree.
Average wind speed.
A weather report can tell you what wind speeds are at a specific weather station. It will also tell you wind direction -- whether the winds are coming from a warm area or a cool area.
Winds above 10 mph / 16 km/h can cancel out any need for an outdoor fan. They can lessen the cooling effect of misting systems and other evaporative coolers by blowing the cool air away from the area you want cooled.
But winds are very much affected by our immediate surroundings. The wind speed at the weather station may different from the wind speed at your exact location.
Wind may be cut off to an area bordered by hills, trees or walls (perhaps your yard), while areas in a canyon (perhaps a nearby park) may experience higher wind speeds than nearby areas. While areas around you are getting lots of wind, you might have a calm area that could really benefit from some outdoor cooling.
Observe your specific area to see if winds are blocked off or intensified there.
If winds are normally high, consider
the cooling of an outdoor shade which is unaffected by winds.
Highest recorded temperatures.
This information can help you prepare for the worst weather! Be prepared to combine cooling methods for maximum cooling. If you’re cooling an enclosed area, consider buying or renting a portable air conditioner that would be powerful enough for even these extreme temperatures. Consider a slightly more powerful mister or swamp cooler, just in case you get hit by one of those blistering days.
This site lets you choose which temperature scale you want to use: U.S. / Fahrenheit or metric / Celsius. Then choose your region, state or province and then the city nearest you. When you get to the page for your city, click on the "All Data" tab. Here you’ll find average air temperature highs for each month of the year. Way at the bottom you’ll also see the average relative humidity for each month of the year. You’ll also find average wind speeds and highest recorded temperatures.
Now that you know a little about your average weather, read a little about each outdoor cooling method and see how well it will work with the weather in your area.
Outdoor shades can easily reduce temperatures by 10°F /5°F and more. In some conditions they can cool up to 40°F / 23°C!
Outdoor shades combine well with every other outdoor cooling method.
Outdoor fans can reduce our "sensation" of the air temperature (how hot it feels) by 4° to 8°F / 2.2° to 4.5°C. (Fans don’t actually lower the temperature, but their cooling breeze against our skin makes us feel cooler.)
Outdoor fans are great for any kind of weather, as long as the air is fairly still. But its cooling effect increases with the amount of humidity in the air. Our bodies cool us by perspiring. The evaporation of this moisture from our bodies cools us. (A natural evaporative cooler!) But the more humid the air, the less our sweat can evaporate; so we feel hotter in humid weather than in dry weather.
As fans move this hot, humid air, our bodies are better able to cool us. In this way we feel the cooling effects of a fan more in humid weather than in dry weather.
If this is not enough cooling for you, consider combining outdoor fans with another method, like outdoor shades. Also consider evaporative coolers ("swamp coolers") or misting fans that combine a fan with evaporative cooling. If you need to cool an enclose area, perhaps a portable air conditioner.
Even portable air conditioners that have a thermostat are affected by the air temperature. Enclosed outdoor areas like tents, sheds, and recreation vehicles get much hotter or cooler as the air temperature changes. If you set the thermostat on your portable air conditioner at 76°F, it will take the unit longer to reach that when the air temperature is 90°F / 32.2°C than when it’s 80°F / 26.7°C.
In fact, since outdoor areas have much less insulation than homes or office buildings, your portable air conditioner may not reach the temperature you set on its thermostat unless it’s powerful enough to cool that area on those hotter days. See our pages on portable air conditioners to get an idea of how powerful an unit you may need for your area.
Portable air conditioners work well in all kinds of weather.
But since they can reduce humidity levels in the areas they are cooling,
they are especially nice to use in humid weather.
Misting systems and misting fans can lower temperatures by as much as 30°F / 16.5°C. But more than other cooling methods, evaporative cooling depends on the relative humidity. All outdoor cooling methods that use evaporation to create a cooling effect, including evaporative coolers and swamp coolers, provide more cooling in drier weather than in more humid weather.
Like misting systems and misting fans, their cooling effect is stronger in drier weather than in humid weather.
The following chart, provided by the California Energy Commission, shows about how much cooling you can expect from evaporative coolers, such as swamp coolers, based on air temperature and relative humidity. Look for a range of air temperature and humidity levels to get an idea of average cooling levels for your area.
Keep in mind that these coolers, along with misting fans, use lots of air flow to circulate the cooled air -- in addition to the air cooled by evaporation, you’ll also feel the softest of breezes, like an outdoor fan. So with these you’ll feel an additional 4° - 6°F / 2.2° - 3.3°C of cooling due to the air blowing across your skin.
If you don’t see air temperatures and relative humidity combinations for your weather on this chart, evaporative coolers are probably not the best choice for you. Consider outdoor fans, portable air conditioners and/or outdoor shades, instead.
Hopefully knowing a little about your weather has helped you focus in on the better outdoor cooling methods for your area.
If you’d like to know more about how these methods compare, go to our comparison page. If you’d like to learn more about each method, visit our extensive articles on:
outdoor shades, misting systems, outdoor fans, and portable air conditioners.