A Heat Advisory is issued by the National Weather Service of the United States within 12 hours of the heat index reaching one of two criteria levels. A warning will be issued if there is a heat index of at least 105°F but less than 115°F for less than 3 hours per day or if nighttime low temperatures are above 80°F for 2 consecutive days. High values of the heat index are caused by temperatures being significantly above normal and high humidities, and such high levels can pose a threat to human life through conditions such as heat stroke.
The following is an example of a Heat Advisory issued by the National Weather Service office in Memphis, Tennessee.
WWUS74 KMEG 111956
URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE MEMPHIS TN
256 PM CDT FRI JUN 11 2010
...PROLONGED HOT AND HUMID WEATHER EXPECTED THIS WEEKEND INTO
EARLY NEXT WEEK...
.A DEEP TROPICAL SOUTHERLY FLOW WILL REMAIN IN PLACE AS A LARGE AREA
OF HIGH PRESSURE BUILDS OVER THE LOWER MISSISSIPPI RIVER VALLEY THIS
WEEKEND. HIGHS SATURDAY THROUGH MONDAY SHOULD RANGE FROM THE MID TO
UPPER 90S ACROSS THE ENTIRE MID-SOUTH...WITH DEW POINTS IN THE
LOW TO MID 70S. THIS WILL MAKE FOR HEAT INDEX VALUES AROUND 105
DEGREES EACH DAY.
THE HEAT AND HUMIDITY WILL NOT SUBSIDE MUCH AT NIGHT WITH TEMPERATURES
ONLY DROPPING INTO THE MID 70S IN MOST RURAL AREAS...TO THE LOWER
80S IN DOWNTOWN MEMPHIS. THIS WILL ADD TO THE DANGER FOR PEOPLE
WHO CANNOT FIND A WAY TO ADEQUATELY COOL DOWN.
CROSS-CRITTENDEN-ST. FRANCIS-LEE AR-PHILLIPS-DUNKLIN-PEMISCOT-
INCLUDING THE CITIES OF...WALNUT RIDGE...PARAGOULD...JONESBORO...
HARRISBURG...BLYTHEVILLE...WYNNE...WEST MEMPHIS...FORREST CITY...
OXFORD...NEW ALBANY...TUPELO...AMORY...ABERDEEN...UNION CITY...
256 PM CDT FRI JUN 11 2010
...HEAT ADVISORY IN EFFECT FROM 10 AM SATURDAY TO 10 PM CDT
THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A HEAT
ADVISORY...WHICH IS IN EFFECT FROM 10 AM SATURDAY TO 10 PM CDT
* HIGH TEMPERATURES IN THE MID TO UPPER 90S COMBINED WITH DEW
POINTS IN THE LOW TO MID 70S WILL MAKE FOR PEAK AFTERNOON HEAT
INDEX VALUES OF 103 TO 108 DEGREES SATURDAY THROUGH MONDAY.
LITTLE RELIEF CAN BE EXPECTED AT NIGHT WITH LOWS IN THE MID 70S
IN MOST RURAL LOCATIONS...TO POSSIBLY THE LOWER 80S IN DOWNTOWN
* THE HIGHEST HEAT INDEX VALUES ARE EXPECTED BETWEEN 1 PM AND 7 PM
* EXCESSIVE HEAT IS THE NUMBER ONE WEATHER KILLER. WHILE THIS
PART OF THE COUNTRY SEES ITS FAIR SHARE OF SUMMER HEAT...THIS
WILL BE THE FIRST HEAT WAVE OF THE SUMMER SO PEOPLE SHOULD BE
ESPECIALLY PREPARED FOR THE DANGERS EXCESSIVE HEAT POSES. YOUNG
CHILDREN...ELDERLY PEOPLE AND THOSE WITH ILLNESSES OR HEART
CONDITIONS ARE MOST AT RISK. LIMIT OUTDOOR ACTIVITIES TO EARLY
IN THE MORNING OR UNTIL EVENING. IF YOU HAVE A WORKING AIR
CONDITIONER USE IT...OR AT LEAST OPEN WINDOWS AND ALLOW AIR TO
A HEAT ADVISORY MEANS THAT A PERIOD OF HOT TEMPERATURES IS
EXPECTED. THE COMBINATION OF HOT TEMPERATURES AND HIGH HUMIDITY
WILL COMBINE TO CREATE A SITUATION IN WHICH HEAT ILLNESSES ARE
POSSIBLE. DRINK PLENTY OF FLUIDS...STAY IN AN AIR-CONDITIONED
ROOM...STAY OUT OF THE SUN...AND CHECK UP ON RELATIVES AND
See also 
- ^ National Weather Service. "Heat Advisory". Glossary - National Weather Service. Retrieved 18 May 2011.
- ^ National Weather Service. "Heat Advisory". Iowa Environmental Mesonet NWS Product Archive. Retrieved 18 May 2011.
External links 
Tue, 14 May 2013 07:41:08 -0700
Welcome to summer, Northfield! Less than two weeks after city schools were closed because of a snowstorm, Northfield residents will face potentially record-breaking heat and a fire risk on Tuesday. The National Weather Service has issued a heat ...
NBC Bay Area
Napa Valley Register
Thu, 02 May 2013 05:03:07 -0700
High temperatures in the Napa area are expected to climb into the low 90s on Thursday, triggering a heat advisory by the National Weather Service for the North Bay region. With the mercury expected to peak at 92 degrees at Napa County Airport, the ...
Mon, 13 May 2013 05:49:25 -0700
Less than two weeks ago many of us had snow coating the ground, and now we're talking about a heat advisory. Near record temperatures is expected Tuesday from noon to 8 p.m. according to the National Weather Service. Temps will be soaring into the low ...
Wed, 01 May 2013 09:31:19 -0700
SALINAS, Calif. - The National Weather Service has issued a heat advisory for the entire San Francisco and Monterey Bay region, which is in effect from 1 p.m. to 9 p.m. Thursday. Record or near record breaking temperatures are likely for many locations.
Perry County Republic Monitor
Fri, 24 May 2013 09:24:27 -0700
And, there doesn't have to be a heat advisory for folks to utilize the park center and the senior center — if it's too hot to handle, both centers are open to the public for a cool-down. “We wouldn't turn anyone away,” Gahan said. “We didn't set this ...
Mon, 20 May 2013 21:12:42 -0700
... Environmental Action Climate Change May Result In 540% Rise In Heat-Related Deaths No Spike In Heat Deaths Despite Record Temperatures Elisabetta Canalis In Hot Car Addresses Dangers Posed To Dogs (VIDEO) Chicago Heat Advisory: Heat Wave ...
Sun, 28 Apr 2013 20:25:20 -0700
It sends out a second van on days when the National Weather Service issues an extreme-heat advisory. The organization has struggled to get water to homeless people in the suburbs, Peña said. “We just started last year going a little into Glendale ...
Mon, 20 May 2013 03:13:34 -0700
Northfield Historical Society to Host Two Events on Thursday • Are Medical Procedures More Expensive in Dakota County or Rice County? • Northfield's Temperature Breaks 90 Degrees • Heat Advisory, Red Flag Warning in Effect Through Tuesday Evening ...
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