EXCESSIVE HEAT WATCH for Wednesday Morning Through Thursday Night

Even North Shore lakefront communities at the shoreline of Lake Michigan are under an Excessive Heat Watch.

URGENT – WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
231 AM CDT TUE JUL 19 2011

What is the record high dew point for Chicago? See below …

MCHENRY-LAKE IL-DUPAGE-COOK-LAKE IN-PORTER-
INCLUDING THE CITIES OF…WOODSTOCK…WAUKEGAN…WHEATON…
CHICAGO…GARY…VALPARAISO
231 AM CDT TUE JUL 19 2011

…EXCESSIVE HEAT WATCH REMAINS IN EFFECT FROM WEDNESDAY MORNING
THROUGH LATE THURSDAY NIGHT…


AN EXCESSIVE HEAT WATCH REMAINS IN EFFECT FROM WEDNESDAY MORNING
THROUGH LATE THURSDAY NIGHT.

* TEMPS/HEAT INDEX…HIGH TEMPERATURES IN THE MIDDLE TO PERHAPS
UPPER 90S WILL COMBINE WITH OPPRESSIVE HUMIDITY VALUES TO RESULT
IN DANGEROUS HIGH HEAT INDICES OF 105 TO 110 DEGREES BOTH
WEDNESDAY AND THURSDAY AFTERNOON. LITTLE RELIEF IS EXPECTED FROM
THE HEAT WEDNESDAY NIGHT…ESPECIALLY IN THE CITY OF CHICAGO WHERE
LOWS WILL BE IN THE LOWER 80S WITH NIGHT TIME HEAT INDEX
READINGS LIKELY TO REMAIN ABOVE 90 DEGREES THROUGH THE NIGHT.

Near record dew points overnight
10:51 PM 78.1°F
11:51 PM 79.0°F
12:51 AM 79.0°F
01:51 AM 78.1°F
RECORD HIGH DEW POINT FOR CHICAGO IS 83°F RECORDED ON 7/30/1999 8:56 AM
A high dew point indicates high humidity

PRECAUTIONARY/PREPAREDNESS ACTIONS…

AN EXCESSIVE HEAT WATCH MEANS THAT A PROLONGED PERIOD OF HOT
TEMPERATURES IS EXPECTED. THE COMBINATION OF HOT TEMPERATURES AND
HIGH HUMIDITY WILL COMBINE TO CREATE A DANGEROUS 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 NEIGHBORS.

Today’s high will show some relief, especially at the lakefront. Arlington Heights has a forecast high of 88°F Tuesday and Lake Forest has forecast high of 78°F Tuesday — more Tuesday highs by the lakefront — Highwood, high 76°F, Lake Bluff, high 77°F, Wilmette, high 78°F, Evanston, high 78°F .