Safety Tips for Concerning Children
Safety Tips for Adults
The Heat Index, sometimes referred to as the apparent temperature is given in degrees Fahrenheit. 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 below. 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 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.
IMPORTANT: 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 Heat Index Chart shaded zone above 105°F (orange or red) shows a level that may cause increasingly severe heat disorders with continued exposure or physical activity.
Never Leave Children, Disabled Adults or Pets in Parked Vehicles
Each year, dozens of children and untold numbers of pets left in parked vehicles die from hyperthermia. Hyperthermia is an acute condition that occurs when the body absorbs more heat than it can handle. Hyperthermia can occur even on a mild day. Studies have shown that the temperature inside a parked vehicle can rapidly rise to a dangerous level for children, pets and even adults. Leaving the windows slightly open does not significantly decrease the heating rate. The effects can be more severe on children because their bodies warm at a faster rate than adults.
Courtesy of San Francisco State University. Use of this graph does not imply NWS endorsement of services provided by San Francisco State University.
How Fast Can the Sun Heat a Car?
The sun's shortwave radiation (yellow in figure below) heats objects that it strikes. For example, a dark dashboard or seat can easily reach temperatures in the range of 180 to over 200°F. These objects (e.g., dashboard, steering wheel, child seat) heat the adjacent air by conduction and convection and also give off longwave radiation (red in figure below) which is very efficient at warming the air trapped inside a vehicle.
The atmosphere and the windows of a car are relatively transparent to the sun’s shortwave radiation (yellow in figure above) and are warmed little. This shortwave energy, however, does heat objects it strikes. For example, a dark dashboard or seat can easily reach temperatures in the range of 180°F to more than 200°F. These objects, e.g., dashboard, steering wheel, childseat, heat the adjacent air by conduction and convection and give off longwave radiation (infrared), which efficiently warms the air trapped inside a vehicle. Learn more about excessive heat and cars.
Normal Temperatures of Puerto Rico and U.S. Virgin Islands
|Maximum Temperatures||Minimum Temperatures|
When to Expect "the Warmest day of the Year" (click here)
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Concientizacion sobre calor extremo
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NOTE: NWS San Juan in collaboration with University of Puerto Rico/Medical Sciences Campus/Department of Environmental Health and University of Puerto Rico/Carolina Campus/Department of Natural Sciences have been working since July 2012 on a couple of research papers about Heat Wave Frequency and Health Consequences in Puerto Rico. The main goal of these local studies is to determine local criteria for Heat Warnings and/or Advisories.