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Extreme Temperatures

Climate and weather have important effects on public health. Extreme heat and cold, severe weather, icy roads, floods, dust storms, lightning, and wildfires can all pose significant hazards to our health and property.

This indicator focuses on exposure to high temperatures. It includes the number of days per year over various high-temperature thresholds for both air temperature and heat index. These data are intended to provide a better understanding of the spatial and temporal patterns of extreme heat in New Mexico and to help communities understand and prepare for the health risks of extreme heat.
Extreme heat raises the risk of heat stress and heat related illnesses, including heat cramps, heat edema, and heat stroke. Extreme heat also can raise morbidity and mortality risk by putting additional physical stress on people with pre-existing health issues, including respiratory, cardiovascular, and renal conditions.
Those most vulnerable to extreme heat tend to be people with pre-existing health conditions, older adults, very young children, people with disabilities, people who work outdoors, people with lower incomes, and people who are socially isolated.
There are several best practices that can help keep you and others safe from heat stress:
  • Limit the amount of time spent in hot conditions.
  • Take breaks in a cooler environment. Continuous heat exposure is more hazardous than intermittent heat exposure.
  • Limit sun exposure (e.g., shade trees, wide brimmed hats).
  • Stay well hydrated.
  • Avoid physical activity during the hottest part of the day. Move strenuous activities to mornings and evenings if possible.
  • Increase air movement with a ceiling or floor fan. If you do not have air conditioning, open your windows at night to let the heat escape.
  • Check on friends, family, and neighbors who may be vulnerable to heat, especially if they do not have anyone else to check on them. Social isolation is one of the biggest risk factors during extreme heat. If you know someone who, for example, is older and has no air conditioning, call or stop by to talk about the weather and make sure they are doing okay.
Temperature is the standard, basic measure of heat. It is what we typically see on thermometers, weather apps on our phones, and TV weather forecasts.

Heat index incorporates both temperature and humidity to provide a more complete picture of how hot the air "feels" to us. For example, a temperature of 90F feels hotter if the air is very humid, because sweat evaporates less rapidly in more humid air, reducing the body's ability to cool itself. Heat index is intended to capture these effects.

In many parts of the country, heat index is almost always higher than air temperature because of persistently high humidity. However, very low relative humidity levels (less than 13%) actually cause heat index to be lower than air temperature, because sweat evaporates very rapidly under these conditions. In New Mexico, such low humidities are common at mid-day during the summer, which causes the maximum heat index to often be lower than the maximum air temperature.
The 90th, 95th, and 98th percentiles for temperature and heat index were calculated using May-September daily maximum temperatures from 1981-2010 for each grid cell in New Mexico. The number of days exceeding those thresholds at each location were then calculated for each year.

"Percentile" refers to the percent of days with temperatures below some threshold. For example, if the 90th percentile for daily high temperature is 83F, then 90% of days had high temperatures less than 83F. Similarly, if the 95th temperature percentile is 87F, then 95% of days had high temperatures less than 87F.

Percentiles are often used for assessing heat risk because people in different regions are adapted to different temperatures. For example, a June temperature of 100F may be quite typical in Phoenix but exceptionally hot and hazardous in Seattle. Percentiles help us understand how unusual a given temperature is in each location.
The NM EPHT Web site is supported by Cooperative Agreement Number 5 U38EH000949 from the Centers for Disease Control and Prevention (CDC). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of CDC. Please use the following citation: " Retrieved Wed, 26 July 2017 22:40:14 from New Mexico EPHT Tracking Public Web site: https://nmtracking.org/ ".

Content updated: Wed, 29 Mar 2017 17:36:38 MDT