• Des Moines
• Waterloo
• Mason City
• Estherville
• Fort Dodge
• Ames
• Marshalltown
• Atlantic
• Lamoni
• Ottumwa

Current Conditions

Current Heat Index Readings	Current Temperatures
Maps Courtesy of the Iowa Environmental Mesonet

Staying Safe

Heat is the #1 weather-related killer in the United States! Here are a few tips on staying safe during episodes of dangerously hot weather:

• First and foremost, minimize your time outside, especially during the hottest parts of the day. Stay in an air conditioned building.
• If you must be outside, wear light-colored and loose-fitting clothing.
• Drink plenty of water or natural juices if you are out in the heat, even if you do not fell thirsty. Avoid alcoholic or caffeinated beverages.
• Think about others! NEVER leave children in a car on even a moderately warm day as conditions in the car can quickly heat to unhealthy levels. Check on the elderly or other people at risk.

For more information, check the National Weather Service's Heat Safety page.

What is the Heat Index?

The Heat Index (HI) is sometimes referred to as the "apparent temperature" and is a measure of how hot it feels outside to the human body. The HI includes the influence of both the actual air temperature and relative humidity. As either value increases, the apparent temperature also increases. The reason why the apparent temperature increases with relative humidity is due to how the body cools itself. The body dissipates almost 90% of its heat through skin perspiration (sweat). Sweating by itself does nothing to cool the body unless the water is removed by evaporation--and high relative humidity hinders evaporation.

To figure out the HI, reference the Heat Index Chart below and find the intersection of the air temperature and relative humidity. The shaded zones on the chart correspond to the probabilities of developing heat-related disorders. It is important to note that the HI values were devised for shady, light wind conditions, thus, exposure to full sunshine can increase HI values by up to 15 degrees.

Heat disorders are generally a result of the body's inability to shed excess heat by sweating or a chemical (salt) imbalance caused by too much sweating. When heat gain exceeds the level the body can remove, or when the body cannot compensate for fluids and salt lost through perspiration, the temperature of the body's inner core begins to rise and heat-related illness may develop. The table below on the right explains the risk to the body from continued exposure to excessive heat and is color coded to match the HI chart.

Heat Index/Apparent Temperature (°F) Possible Heat Disorders for People in High Risk Groups 130°F or Higher Heat/Sunstroke HIGHLY LIKELY with continued exposure 105°F - 130°F Sunstroke, heat cramps, or heat exhaustion LIKELY, and heatstroke POSSIBLE with prolonged exposure and/or physical activity 90°F - 105°F Sunstroke, heat cramps, or heat exhaustion POSSIBLE with prolonged exposure and/or physical activity 80°F - 90°F Fatigue POSSIBLE with prolonged exposure and/or physical activity

For more information on how heat affects the body, see the National Weather Service's Heat Safety webpage.