University of Houston-Victoria

Emergency Management

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Extreme Heat

The Victoria area has very hot summers, and sometimes spring and fall temperatures reach dangerous levels as well.  Knowing heat safety and how to recognize heat-related illnesses can help save you or someone else.

Heat Watch vs. Warning

Excessive Heat Warning - Take Action! An Excessive Heat Warning is issued within 12 hours of the onset of extremely dangerous heat conditions. The general rule of thumb for this Warning is when the maximum heat index temperature is expected to be 105° or higher for at least 2 days and night time air temperatures will not drop below 75°; however, these criteria vary across the country, especially for areas not used to extreme heat conditions. If you don't take precautions immediately when conditions are extreme, you may become seriously ill.

Excessive Heat Watches - Be Prepared! Heat watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours. A Watch is used when the risk of a heat wave has increased but its occurrence and timing is still uncertain.

Heat Advisory - Take Action! A Heat Advisory is issued within 12 hours of the onset of extremely dangerous heat conditions. The general rule of thumb for this Advisory is when the maximum heat index temperature is expected to be 100° or higher for at least 2 days, and night time air temperatures will not drop below 75°; however, these criteria vary across the country, especially for areas that are not used to dangerous heat conditions. Take precautions to avoid heat illness. If you don't take precautions, you may become seriously ill.

Heat Related Illnesses

During extremely hot and humid weather, your body's ability to cool itself is challenged. When the body heats too rapidly to cool itself properly, or when too much fluid or salt is lost through dehydration or sweating, body temperature rises and you or someone you care about may experience a heat-related illness

Humidity Matters: Relative humidity is a measure of the amount of moisture in the air. Sweat does not evaporate as quickly when the air is moist as it does in a dry climate. Since evaporation of sweat from the skin is one of the ways the human body cools itself on a hot day, high humidity reduces our natural cooling potential and we feel hotter. Low humidity can also be a problem for outdoor workers in hot, desert-like climates. Sweat evaporates very rapidly in low humidity, which can lead to severe dehydration if a person does not drink enough water throughout the day.

additional information: OSHA

Heat IndexRisk LevelPlan
Less than 91°F Lower (Caution) Basic heat and safety planning
91° to 103°F Moderate Implement precautions and heighten awareness
103° to 115°F High Additional precautions to protect workers
Greater than 115°F Very High to Extreme Triggers even more aggressive protective measures

 

NOAA INDEX RISK LEVELPROTECTIVE MEASURES
Less than 91°F Lower (Caution) Basic Heat safety and planning
91-103°F Moderate Implement precautions and heighten awareness
103-105°F High Additional precautions to protect workers
Greater than 115°F Very High to Extreme Triggers even more aggressive protective measures