Excessive heat warning

An excessive heat warning is a notice issued by the National Weather Service of the United States when temperatures exceeds 100°F^{[citation needed]} (37°C). When this is in effect, heat stroke is extremely likely to occur in anyone who is outside in intense sunlight for an extended period of time, which poses a serious threat to life. Athletes and hikers, in particular, need to be very careful under the effects of a heat warning, as those groups of people are the most vulnerable to heat exhaustion. Local weather agencies, particularly those where excessive heat is less frequent or in areas with deserts or mountainous terrain, often set their own criteria.

The following is an example of an excessive heat warning issued by the National Weather Service office in San Antonio, Texas on June 11, 2022 during a severe heat wave.

692
WWUS74 KEWX 111801
NPWEWX

URGENT - WEATHER MESSAGE
National Weather Service Austin/San Antonio TX
101 PM CDT Sat Jun 11 2022

TXZ171>173-191>193-203>208-219>222-120900-
/O.UPG.KEWX.HT.Y.0005.000000T0000Z-220613T0000Z/
/O.NEW.KEWX.EH.W.0001.220611T1801Z-220613T0000Z/
Llano-Burnet-Williamson-Hays-Travis-Bastrop-Uvalde-Medina-Bexar-
Comal-Guadalupe-Caldwell-Frio-Atascosa-Wilson-Karnes-
Including the cities of Llano, Burnet, Georgetown, San Marcos,
Austin, Bastrop, Uvalde, Hondo, San Antonio, New Braunfels,
Seguin, Lockhart, Pearsall, Pleasanton, Floresville,
and Karnes City
101 PM CDT Sat Jun 11 2022

...EXCESSIVE HEAT WARNING IN EFFECT UNTIL 7 PM CDT SUNDAY...

* WHAT...Air temperatures ranging from 103 to 107, as well as heat
  index values up to 105 to 110 expected.

* WHERE...Portions of south central Texas.

* WHEN...Until 7 PM CDT Sunday.

* IMPACTS...Extreme heat and humidity will significantly
  increase the potential for heat related illnesses,
  particularly for those working or participating in outdoor
  activities.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

^[1]

• Extreme cold warning – the polar opposite of an Excessive heat warning

• National Weather Service