Heat Index (2024)

La Crosse, WI

Weather Forecast Office

Weather.gov > La Crosse, WI > Heat Index

Heat Index
Temperature vs. Humidity

How to read the chart: find the temperature on the left hand side, then move to the right until you find the column for the approximate relative humidity. That number will be the temperature that it will "feel" like. Example: A temperature of 95 and relative humidity of 50% will "feel" like 107 degrees.

0%5%10%15%20%25%30%35%40%45%50%55%60%65%70%75%80%
115103107111115120127135143151
11099102105108112117123130137143151
1059597100102105109113118123129135142149
1009193959799101104107110115120126132136144
958788909193949698101104107110114119124130136
90838485868788909193959698100102106109113
857879808182838485868788899091939597
807374757677777879798081818283858686
756969707172727373747475757676777778
706464656566666767686869697070707071

IMPORTANT: Heat index values were devised for shady, light wind conditions. Exposure to full sunshine can increase values by up to 15 degrees! Also, strong winds, particularly with very hot, dry air, can be extremely hazardous.

Or, if you know the temperature and the dewpoint, figure out the heat index and relative humidity (RH) using this calculator.

HEAT INDEX using Temp and Dew Point

HEAT INDEX using Temp and RH

Dew Point vs. Humidity

The dew point is the temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity (RH) of 100%. At this point the air cannot hold anymore water in the gas form. If the air were to be cooled even more, water vapor would have to come out of the atmosphere in the liquid form, usually as fog or precipitation.

The higher the dew point rises, the greater the amount of moisture in the air. This directly effects how "comfortable" it will feel outside. Many times, relative humidity can be misleading. For example, a temperature of 30 and a dew point of 30 will give you a relative humidity of 100%, but a temperature of 80 and a dew point of 60 produces a relative humidity of 50%. It would feel much more "humid" on the 80 degree day with 50% relative humidity than on the 30 degree day with a 100% relative humidity. This is because of the higher dew point.

So if you want a real judge of just how "dry" or "humid" it will feel outside, look at the dew point instead of the RH. The higher the dew point, the muggier it will feel.

General comfort levels that can be expected during the summer months:

  • less than or equal to 55: dry and comfortable
  • between 55 and 65: becoming "sticky" with muggy evenings
  • greater than or equal to 65: lots of moisture in the air, becoming oppressive
Heat Index/Heat Disorders
Heat IndexPossible heat disorders for people in higher risk groups
80-90Fatigue possible with prolonged exposure and/or physical activity.
90-105Sunstroke, heat cramps and heat exhaustion possible with prolonged exposure and/or physical activity.
105-130Sunstroke, heat cramps or heat exhaustion likely, and heat stroke possible with prolonged exposure and/or physical activity.
130 or higherHeatstroke/sunstroke highly likely with continued exposure.
Heat DisorderSymptomsFirst Aid
SunburnRedness and pain. In severe cases swelling of skin, blisters, fever, and headaches.Ointments for mild cases if blisters appear and do not break. If breaking occurs, apply dry sterile dressings. Serious, extensive cases should be seen by a physician.
Heat CrampsPainful spasms usually in muscles of the legs and abdomen possible. Heavy sweating.Firm presure on the cramping muscles, or gentle massaging to relieve the spasm. Give sips of water. If nausea occurs, discontinue use.
Heat ExhaustionHeavy sweating, weakness, skin cold, pale and clammy. Pulse thready. Normal temperature possible. Fainting and vomiting.Get victim out of sun. Lay down and loosen clothing. Apply cool, wet cloths. Fan or move victim to air conditioned room. Sips of water. If nausea occurs, discontinue use. If vomiting continues, seek immediate medical attention.
Heat Stroke (sunstroke)High body temperature (106 F or higher). Hot dry skin. Rapid and strong pulse. Possible unconsciousness.Heat stroke is a severe medical emergency. Summon emergency medical assistance or get the victim to a hosiptal immediately. Delay can be fatal.

Move the victim to a cooler environment. Reduce body temperature with cold bath or sponging. Use extreme caution. Remove clothing, use fans and air conditioners. If temperature rise again, repeat process. Do not give fluids.

Safety Tips
  • Slow down. Strenuous activities should be reduced, eliminated, or rescheduled to the coolest time of the day. Individuals at risk should stay in the coolest available place, not necessarily indoors.
  • Dress for summer. Lightweight, light-colored clothing reflects heat and sunlight, and helps your body maintain normal temperatures.
  • Foods (like proteins) that increase metabolic heat production also increase water loss.
  • Drink plenty of water or non-alcoholic fluids. Your body needs water to keep cool. Drink plenty of fluids even if you don't feel thirsty.
  • Do not drink alcoholic beverages.
  • Spend more time in air-conditioned places. Air conditioning in homes and other buildings markedly reduces danger from the heat. If you cannot afford an air conditioner, spending some time each day (during hot weather) in an air conditioned environment affords some protection.
  • Don't get too much sun. Sunburn makes the job of heat dissipation that much more difficult.
Heat Index (2024)

FAQs

How to solve heat index? ›

The heat index formula is expressed as,
  1. HI= c1+c2T+c3R+c4TR+c5T2+c6R2+c7T2R+c8TR2+c9T2R2 In this formula, ...
  2. Example 1. Determine the heat index if the temperature is 197∘F and the relative humidity is 80%. ...
  3. Heat Index (HI) = 1410.25oF. Therefore, the heat index is 1410.25 Fahrenheit.
  4. Example 2. ...
  5. Heat Index = 1273.47 oF.

What is too hot for the heat index? ›

If you are exposed to direct sunlight, the heat index value can be increased by up to 15°F. As shown in the table below, heat indices meeting or exceeding 103°F can lead to dangerous heat disorders with prolonged exposure and/or physical activity in the heat.

What can you say about the heat index? ›

The heat index tells you what it “feels like” outside when you factor in the humidity. For example, if it's 98 degrees Fahrenheit (36.7 Celsius) with 55% relative humidity, it might feel more like a scorching 117 F (47.2 C).

What is an unsafe heat index? ›

Heat Index

Possible heat disorders for people in higher risk groups. 130 or higher. Heatstroke/sunstroke highly likely with continued exposure. 105-130. Sunstroke, heat cramps or heat exhaustion likely, and heat stroke possible with prolonged exposure and/or physical activity.

What does 80 degrees with 80 humidity feel like? ›

But as the moisture level increases, the temperature you feel will also rise. For example, on an 80-degree day, a 60% relative humidity will create a heat index of 82 degrees Fahrenheit (28 degrees Celsius). Increase that to 80% relative humidity, and the perceived temperature rises to 84 (29 degrees Celsius).

What is the formula for calculating heat? ›

The quantitative relationship between heat transfer and temperature change contains all three factors: Q = mcΔT, where Q is the symbol for heat transfer, m is the mass of the substance, and ΔT is the change in temperature. The symbol c stands for specific heat and depends on the material and phase.

How hot is too hot for humans? ›

A new study suggests that once temperatures hit 104 to 122 degrees, our bodies may stop working optimally.

How hot is considered extreme heat? ›

In most of the United States, extreme heat is a long period (2 to 3 days) of high heat and humidity with temperatures above 90 degrees.

Is 400 considered high heat? ›

What is High Heat Cooking? The definition of high temperature cooking is anything that involves a temperature between 400 F (205 C) to 600 F (315 C). This temperature allows liquid to evaporate and achieve a thick texture. It is also ideal for sauteing vegetables to retain their freshness and crispiness.

Why is it so hot right now? ›

But climate change, caused by human activities that release plant-warming gasses like carbon dioxide, is causing global temperatures to be warmer than normal.

What is the highest recorded heat index in the world? ›

World: Highest Temperature
Record Value56.7°C (134°F)
Date of Record10 /7 [July] / 1913
Formal WMO ReviewYes (2010-2012)
Length of Record1911-present
InstrumentationRegulation Weather Bureau thermometer shelter using maximum thermometer graduated to 135°F
1 more row

How to reduce heat index? ›

What You Can Do to Reduce Heat Islands
  1. Increase shade around your home. ...
  2. Install green roofs. ...
  3. Install cool roofs. ...
  4. Use energy-efficient appliances and equipment. ...
  5. Check on your friends, family, and neighbors.
Jul 10, 2023

How hot is too hot to work inside? ›

Heavy and very heavy work carry the highest risk of heat-related illness.
Effective WBGT (°C)Unacclimatized workers
Below 70°F (21°C)Low risk of heat-related illness
70 to 77°F(21 to 25°C)Strenuous work possibly unsafe
Above 77°F (25°C)High risk of heat-related illness with strenuous work

Can I leave work if it's too hot? ›

While there are no specific federal regulations about working in extreme cold or heat, you do have a right to a workplace “free from recognized hazards .” That includes exposure to extreme cold and heat. Some states do have more rigorous rules regarding heat, and you can find the state plans here .

How hot is too hot to be outside? ›

How hot does it have to be before it's safer to be inside? Oller points to the heat index for this one: Temps between 90 and 105 degrees Fahrenheit are considered “extreme caution,” and anything above falls under the “danger” and “extreme danger” categories.

What is the heat index calculator? ›

This calculator estimates the temperature felt by the body as a result of air temperature and relative humidity.

What is the formula for heat load index? ›

The following steps outline how to calculate the Heat Load Index (HLI). First, determine the air temperature (T) in degrees Celsius. Next, determine the wet bulb temperature (W) in degrees Celsius. Next, use the formula: HLI = 0.5 * ((T + W) – 0.31 * (T – 14.4)).

How do you calculate thermal index? ›

The thermal index (TI) is defined as the ratio W/Wdeg, where W is the acoustic power emitted by the transducer at any time, and Wdeg is the power required to cause a maximum temperature rise of 1°C anywhere in the beam, contributed by ultrasound absorption alone.

What is the formula for calculating heat loss? ›

The heat loss in the wall is measured in BTUs and the formula is U value x Wall area x Delta T. In our example, this would be: . 07 x 164 x 28 = 321.44 BTUH (British Thermal Units per Hour). This is the amount of heat that is escaping through the exterior walls based on the amount of insulation in them.

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