WILLMAR -- By midafternoon Monday, the heat index in Willmar had soared to 100 degrees and Rob Baumgarn, Willmar Community Education and Recreation coordinator, was keeping a close watch on the thermometer.
Any hotter, and he and his staff would have to start talking about whether to cancel community rec activities for the day.
"We constantly are checking the heat index," Baumgarn said. "If it reaches 100 to 105, that's where we start contemplating about what we should do."
A heat wave has had the region simmering since the weekend. With temperatures not expected to moderate until the end of the week, local residents are bracing for a Fourth of July holiday that's going to be a scorcher.
Jo DeBruycker, manager of the Health Learning Center at Affiliated Community Medical Centers, had this advice Monday for coping with the hot weather: "Slow down, seek shade and stay hydrated."
The very young and the very old are most at risk for heat-related illness, she said.
But even healthy younger adults can succumb, especially if they exercise too vigorously or don't drink enough fluids, she said. "Just because you've tolerated heat and humidity in the past doesn't always mean you'll be able to do it again. This week of heat and humidity is something we've not experienced for quite a period of time."
The National Weather Service is predicting highs in the mid-90s through at least Thursday. Nighttime lows will only cool off to the low 70s.
Runners in the Green Lake Road Race in Spicer on Sunday competed in temperatures that reached the low 80s by mid-morning. Although water stops were plentiful, several runners felt the heat and about half a dozen required brief treatment by emergency medical technicians.
Organizers of Spicer's Fourth of July festivities this week expect the heat to make a minimal dent in the crowd, however. The Independence Day celebration on Wednesday is one of the area's largest and includes a morning parade and an evening fireworks display over Green Lake.
"We're still planning for a great turnout," said Sabrina Lere. "We expect the Dairy Queen and the food vendors and the lake to be very busy. ... There's lots of places in Spicer for people to be able to cool off."
The Minnesota Department of Health issued a list Monday of precautions to take for managing the heat: Drink plenty of fluids -- but avoid alcohol, which is dehydrating, and heavily sugared drinks. Stay indoors, preferably in air conditioning. If you don't have air conditioning, spend some time in an air-conditioned public place such as a shopping mall or library.
If you're outdoors, dress in loose, lightweight clothing and take frequent breaks in the shade or in a cool place.
Small children and older adults are more vulnerable to the effects of heat, DeBruycker said. "They dehydrate more easily. They might not always show the signs."
Small children should be protected outdoors with hats or a place in the shade, she said. "Don't let them out in the blazing sun."
The state Health Department is urging people to check regularly on family members and neighbors who are older or chronically ill and at risk of heat-related illness.
Some medications also can result in increased susceptibility to heat. These include some tranquilizers, psychotropic drugs, medications for Parkinson's disease that inhibit sweating, and diuretics, which are often prescribed to treat high blood pressure.
DeBruycker put in a word on behalf of pets as well. When it's this hot, dogs and cats are safer and more comfortable indoors where it's air-conditioned, she said.
While the heat is on, strenuous activity should be limited to the morning or evening hours, when it's cooler, health officials advise.
For this reason, Willmar Community Education and Recreation avoids scheduling activities during the hottest part of the afternoon, Baumgarn said.
Popular events such as ball games are usually in the evening, he said. "It's very rare that we will cancel a 6 o'clock event. And we always advise people, 'If you don't feel you can be out there, don't come.'"
So far this summer, the hottest weather has been on weekends, when fewer activities are planned, he said. And because of the Fourth of July holiday, no youth programs are scheduled this week.
"We deal with rain and we deal with heat," Baumgarn said. "I just wish that there was a happy medium."