Table of Contents
Extreme heat is defined as weather that is “substantially hotter and/or more humid than average for a location at that time of year” (Hazard Identification and Risk, 2011, p. 31) The Heat Index, which measures the “apparent temperature” when considering both air temperature and humidity, is used by organizations like the National Weather Service to identify extreme heat days. Extreme heat is particularly dangerous when occurring for a prolonged period (known as a “heat wave”).
Summertime temperatures are lower in the mountains and at higher elevations; therefore, extreme heat hazards in Colorado tend to occur in the Front Range, Grand Valley, Eastern Plains, and extreme southwest (Colorado Natural Hazards Mitigation Plan, 2013, p. 3-38). The number of extreme heat days in Colorado has been rising in recent years. In Denver, for instance, seven of the ten hottest years since 1874 occurred from 2000-2012 (NWS Boulder Denver, n.d.b). In Fort Collins, the number of days per year over 90 degrees from 2000-2013 was almost double the historic average (Extreme Heat, 2014). While the overall mortality rate due to extreme heat events has been declining in Colorado over the past several decades, largely due to the increased availability of air conditioning and preparedness for extreme heat hazards, certain groups remain vulnerable. Past extreme heat events have caused damage to state and local infrastructure, especially roadways and utility networks.
Extreme heat can help create the conditions for drought and can exacerbate the impacts of drought by putting additional stress on available water supplies. Extreme heat can also lead to increased storm activity, which is linked to both high wind and flash flood hazards. It can also contribute to the spread of wildfires.
Colorado Natural Hazards Mitigation Plan
The Colorado Natural Hazards Mitigation Plan is a key resource for an overview of extreme heat hazards and summaries of national and state-level data on extreme heat.
National Weather Service
The National Weather Service is a key resource for the forecasting of extreme heat events and for the issuance of advisories and warnings.
