What Is the “Feels Like” Temperature?

HygrometerThis summer has been a SCORCHER. Recently, the temperature outdoors reached 92o. This is quite warm by South Florida standards, where we have the Gulfstream current and prevailing winds that temper our weather. The really astonishing factor was, my weather app said “feels like 107o. How does my weather app know what it feels like, and what does that mean?


There is a lot of truth to the saying, “It’s not the heat, it’s the humidity.” In reality, both affect our comfort as I learned once on a week-long business trip to Phoenix, Arizona. I was at first astonished to see daily high temperatures above 100o F but soon learned that I could be quite comfortable due to the low (5%) relative humidity. By drinking lots of water and wearing loose-fitting cotton clothing, I was quite comfortable during my stay there.

Says the National Weather Service:

The Heat Index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature. To find the Heat Index temperature, look at the Heat Index Chart above or check our Heat Index Calculator. As an example, if the air temperature is 96°F and the relative humidity is 65%, the heat index–how hot it feels–is 121°F. The red area without numbers indicates extreme danger. The National Weather Service will initiate alert procedures when the Heat Index is expected to exceed 105°-110°F (depending on local climate) for at least 2 consecutive days.

NWS also offers a Heat Index chart for area with high heat but low relative humidity. Since heat index values were devised for shady, light wind conditions, exposure to full sunshine can increase heat index values by up to 15°F. Also, strong winds, particularly with very hot, dry air, can be extremely hazardous.


The system that cools your home is designed to both cool and dehumidify the air to 74o F. and 50% relative humidity. Under these conditions, the temperature “feels like” the thermostat setting. This will be true as long as the humidity stays around 50%. When the air conditioner fails to take humidity out of the air at the proper rate, the home feels uncomfortable.

There are several possibilities:

  1. It is cool outside, so the air conditioner will not run enough to take out the humidity produced from cooking, washing, and other sources.
  2. The air conditioner is over-sized. It cools the home but shuts off before it can dehumidify.
  3. Poor equipment selection. South Florida is more humid than most of the nation. Some manufacturers design their equipment so it is more effective in less humid regions.
  4. Duct leakage can cause humidity to be drawn into your home every time the fan comes on. At the same time, warm air from the outdoors and the attic cause the air conditioner to run longer, and better dehumidification. This is a losing proposition, as the home feels comfortable on all but the warmest of days.
  5. Equipment low on refrigerant will cool the air but will lose control of humidity. Health can be affected and mold growth promoted at humidity levels above 60%.


Digital thermometer with a small house next to itIf you find you need to set the thermostat a few degrees lower than before, just to keep comfortable, you may have problems that are not obvious. A thorough mechanical inspection and diagnosis is necessary for optimum cooling and dehumidification.

We recommend you subscribe to a Comfort Club Membership with Complete Comfort. They will make certain your maintenance is performed as-needed by a technician trained to recognize potential problems and ensure optimum performance. They will make recommendations to best ensure reliable cooling for months and years to come. Call (561) 529-6262 today.