JACKSONVILLE, Fla. -- The high temperature Friday broke a record set in 1940 and forecasters call for one more day of above-average heat and humidity before a storm front brings temperatures back down to earth.

After a high of 102 degrees at Jacksonville International Airport and feel-like temperatures from 109 in Jacksonville to 117 in Brunswick, the National Weather Service extended the current heat advisory to Saturday at 7 p.m.

Forecasters said high humidity from the Gulf of Mexico and Atlantic is exacerbating above-average temperatures.

"In late July and August, the tropical rush of humidity comes in from the south, and that can magnify the heat," Channel 4's chief meteorologist John Gaughan said at 5 p.m.

HOT NUMBERS      Friday was the sixth day in a row with a high above 95 degrees Friday's 102° breaks 60-year-old record Fourth triple-digit high this summer -- the most in more than 10 years Only 5 of the past 60 days have been below normal June 2010 was the hottest June on record Last July averaged below normal temperatures

Gaughan said the extreme heat should ease by Sunday, but not before some storms with potentially heavy downpours and intense lightning pass through northeast Florida.

High heat index values can create dangerously hot conditions where individuals may become critically exhausted if outdoors. People are urged to drink plenty of fluids, stay in an air conditioning if possible, remain out of the sun and check on relatives and neighbors who may be sensitive to heat-related illnesses.

"We had the hottest June on record, and if we continue with these temperatures, this may be the hottest July yet," Channel 4 meteorologist Richard Nunn said.

Emergency room doctors at Memorial Hospital report a 50 percent increase in patients showing heat-related ailments this summer over previous summers.

"Occasionally we do see somebody who is in really bad, life-threatening condition from heat-related problems," Dr. Mark Broderur told Channel 4's Jennifer Bauer. "The biggest problem is not keeping up with fluids."

Doctors said when it gets this hot, sometimes water isn't enough and people should consider a sports drink to replace the electrolytes that are lost through sweating.

Broderur said they have also treated people with burns on the bottoms of their feet from walking on hot sand or pavement.

"We were just walking from the beach and we couldn't make it; we had to put on our flip-flops," beachgoer Lamonte Watkins said.

The entire south is roasting under high temperatures and humidity and heat advisories extend all the way to the Great Plains.