Lawrence already had its first 100-degree day of the year on Tuesday and, if you believe the forecast, it could have at least one more by the end of the week.

So Lawrencians need to focus on staying hydrated and keeping cool.

“We’ve had a relatively mild summer until recently, and all of a sudden it turned very hot,” said Charles Yockey, a pulmonologist at Lawrence Memorial Hospital. “When temperatures are above 90 and humidity above 75 percent, it’s a disaster for people who aren’t acclimated to the heat.”

When it’s this hot, Yockey said, if you’re not consuming enough fluids to urinate every two to three hours you need to drink more. And people on dehydrating medications — for example, diuretics or medications for conditions like hypertension — should be extra cautious.

Despite the conditions this week, Lawrence Memorial Hospital’s emergency room hasn’t seen any patients recently for heat-related illness.

Medical professionals say one easy way to tell that you’re suffering from a heat-related illness is if it’s really hot and you stop sweating. After that, then you may feel dizzy and light-headed, hallucinate, have a seizure or pass out, leading to heat stroke. If you feel a heat-related illness coming on, get into the shade or somewhere with air conditioning and drink water. Or, better yet, try to avoid getting into that situation in the first place.

“What we tell people is if it’s this hot and you have to be outside, try to avoid the hours between 10 a.m. and 2 p.m. If you have to work outside, definitely keep yourself hydrated,” said Kim Ens, director of clinic services for the Lawrence-Douglas County Health Department. “For people who are elderly or young kids, when it’s that hot they need to stay inside. If they don’t have air conditioning in the middle of the day, they want to find a place that does.”

“Even for people who are used to working outside, they really need to be a bit more cautious,” she added. “It’s really hard on your body when it gets this hot and humid.”

Over at the U.S. Specialty Sports Association Fastpitch World Series, being held this week at the Clinton Sports Complex, USSSA state director Jeremy McDowell said the games are being stretched out so teams and officials can take water breaks and play at a slow pace.

“We have been sending reminders on the heat to the coaches and making sure they know the importance of hydrating this week,” he said. “We have a good track record when dealing with these events and the heat and always make sure the athlete is put first.”

Lawrence-Douglas County Fire-Medical has received several calls recently from residents suffering from dehydration.

“The best practice is to hydrate early,” said Fire-Medical division chief Eve Tolfree. “You can’t start hydrating the day of. You need to start hydrating and forecast it out several days before. That way your bodies are not going to try to play catch-up.”

That goes for Kansas University students returning to school soon.

“Hopefully everybody, as they migrate back to Kansas, will start hydrating early; that’s the key,” Tolfree said.

Other advice from local health care professionals includes:

• Walk in the morning rather than during the day.

• Don’t drink caffeine and alcohol, as they are dehydrating.

• Don’t take salt pills.

• Cover your head from the sun.

• Wear sunscreen.

• Stay in the shade.

• Hold athletic practices indoors or in the evenings.

• Check on your elderly neighbors.

• Don’t ever leave a person or pet in a non-air-conditioned car with the windows up.