The temperature gauge ticked upward, topping out at 89 degrees just after lunch hour in one of the state's hottest public school classrooms.

With water bottles sitting on many desks, 'Ewa Beach Elementary second-graders tried to pay attention after a sweaty half-hour outside for recess and lunch Thursday during the first full week of the new school year.

But heads sagged and chins rested on hands.

Teacher Jadene Wong dabbed at perspiration as droplets of sweat collected around her eyes. She's seen students in her classroom nod off in the afternoon heat.

"Yesterday we had a boy fall out of his seat because he fell asleep," said school principal Sherry Kobayashi.

With Honolulu temperatures forecast to hit between 85 and 90 degrees this week — and expected to stay high — parents are being urged to send children to class toting water and wearing light clothing that isn't confining. Although schools are adding extra fans to classrooms, and some teachers are bringing theirs from home, the fans often simply blow around the hot air.

"It's very difficult for the kids to learn; it's very uncomfortable," said Kobayashi, who saw her school get a new six-classroom building this year, only to discover as school opened that half the air-conditioning system didn't work.

Jessica Nangauta's combination fifth- and sixth-grade class moved immediately to the library. And because most of her kindergartners aren't starting until tomorrow, Kobayashi is hoping the problem will be fixed before then.

"We put in 'trouble' calls. And we got them fans for temporary relief," she said.

While the state isn't seeing the 100-plus-degree killer heat that hit the West Coast over the past month and now has moved to the Midwest and East, teachers and principals are saying it seems hotter than usual for Hawai'i's hottest summer months. And with the new unified public school calendar that brought virtually everyone back to school at the end of July, schools that used to be out in August are feeling especially vulnerable.

Numerous studies have shown that when students struggle with poor conditions in their school — everything from dilapidated structures to hot air — they don't perform as well.

LUCKY 18

Only 18 of the state's 258 public schools, excluding charter schools, are air-conditioned, with two more under construction. That leaves the other schools to struggle with a multitude of fans, occasional window air-conditioners and other donated air conditioners that aren't always usable because of limitations with the schools' electrical infrastructure.

Parent Stephanie Walker, whose 5-year-old son, Caleb, started kindergarten Friday at Keone'ula Elementary School, said his teacher stressed the need to bring water. The school is operating temporarily at 'Ewa Beach Elementary until a new school location opens in January.

"It's a requirement that every parent send a half pint of water every day," she said. "They have mandatory water times (during the day) to take a break."

Pediatrician Dr. Melinda Ashton of Kapi'olani Medical Center for Women & Children suggests children drink at least three servings of water during their school day: the first by 10:30 a.m., the second during lunch recess and the third by the end of the school day.

"Kids just don't drink enough water so we see kids with headaches at 2 and 3 in the afternoon and they're just dry," said Ashton, who is medical director for patient safety and quality services for Hawai'i Pacific Health.

But Ashton said Hawai'i children should not be at the same risk as those suffering Mainland heat.

"Although it's hot and uncomfortable, it tends not to be the same level of danger for heat-related illness unless they're not drinking enough water," she said. "Our kids aren't at risk of heat stroke unless you've got them out exercising for a couple of hours."

Pohakea Elementary parent coordinator Lori Mo'o sends her 9-year-old son, Ezra, a fourth-grader at Mauka Lani, to school with a jug crammed with ice-cubes and then filled with water. But her 13-year-old, Aysha, an eighth-grader at the air-conditioned Kapolei Middle school, needs none of it.

"My daughter takes a sweater to school," she says.

Aysha says she notices a difference in how much easier it is to pay attention.

"We can concentrate more," she says of the cooler classrooms. "Since it's cooler it takes your mind off being hot."

SHORT ATTENTION SPANS

Of the hottest schools in the state, Mokulele Elementary at Hickam Air Force Base is the only one to switch from a traditional calendar last year to year-round calendar this year. Being in session during August for the first time has meant some changes, such as having to turn a sweltering portable classroom building into a storage room.

"Generally it's for PE, but it's a sauna," said vice principal Bart Nakamoto. "With the fans it would be in the 90s. Without fans I wouldn't want to be in there."

At Campbell High School, also on the list of the state's hottest schools, senior Royce Akiona, 17, thinks the heat in the classrooms may encourage students to skip out, while senior Jordan Samante, 17, says it's distracting.

"You're in class and listening to the teacher talk and you're not paying attention because you're like 'it's so hot,' " Samante said.

Five years ago, the Board of Education decided the state's hottest schools should be retrofitted with central air condition-ing rather than leaving the solution to the fickle winds.

"Under board policy classrooms exceeding the threshold of 80 degrees become eligible for air conditioning," DOE planner Sanford Beppu said.

Using average school temperature data from the 1990s, the department created a priority list for air-conditioning projects in the steamiest schools.

"It's tough to beat the heat," said Pohakea Elementary principal Stephen Schatz, whose school is third from the top of the hot list. "You can go under the trees but it's still hot."

PRICEY PROJECTS

Kihei Elementary on Maui, which tops the list of hottest schools, will see the first $1.2 million phase of its new central air-conditioning system completed by December, DOE planners say. Construction on the next two phases for the remaining buildings starts next summer.

This year the Legislature also increased the usual funding to retrofit the hottest schools with central air, going from $2 million allotted last year to $10 million now. With each retrofit costing $3 million to $5 million, that means two to three new air-conditioning projects can be launched this year.

But there's a down side to those improvements. Every school with air conditioning increases the system's electric bill. Next year the DOE expects to pay $37 million for electricity, a 65 percent increase from two years ago.

With schools in the driest areas of the islands, in particular, facing severe heat conditions each summer, the DOE also has been looking at other new ways to improve the learning environment that won't create even higher costs.

"We're designing our upcoming projects with energy-efficiency guidelines," Beppu said. "The design will allow us to not have a need for such a high level of air conditioning. ... It still could be air-conditioned but more efficiently."

Designs will follow "green" guidelines that include an expansive high ceiling that serves to funnel hot air upward and leave cooler air below.

ANYTHING TO STAY COOL

Meanwhile, the hottest schools struggle on.

Across 'Ewa Beach Elementary's campus from the wing of hot second-grade classrooms, it's about 15 degrees cooler in the climate-controlled library and office building.

Kobayashi, the school principal, suspects students might "purposefully misbehave" or find other reasons just to go there.

Third-grader Noah Leggett said last year students stretched out a project by a couple of days just to spend extra time in the cooler library.

"When we did a report on our animals we took a week," the 8-year-old said.

His mother, Cathy Leggett, the school's Parent Community Network Coordinator, says her children always complain of the heat, and Noah comes home with the back of his T-shirt wet from sweat and his head dripping despite his new shorter haircut.

"It's so hot for these poor kids," she says. "It's a given — they're always hot."

Reach Beverly Creamer at bcreamer@honoluluadvertiser.com.