Oahu’s energy use hit a 2015 high on Thursday as warm weather pushed residents to use more electricity.

The peak energy use Thursday was 1,246 megawatts, a 9 percent increase from electricity use the same day last year — when residents used 1,143 megawatts — and the highest so far this year.

“Whenever it gets hot and humid, we see an increase in the use of electricity,” said Darren Pai, Hawaiian Electric Co. spokesman. “The combination of feeling hot and sticky leads customers to use more air conditioning, which increases the demand for electricity.”

The jump in energy use coincides with El Nino’s hold on the islands; there have been dozens of record-breaking temperatures this summer. The waters in the Central Pacific in August were the warmest in more than 17 years, as the current El Nino is the third strongest on record, behind 1997-98 and one in 1987-88 that peaked early.

“Historically, demand reaches its peak around October, when it is usually both hot and humid,” Pai said. “Weather conditions are not following the usual trends this year, and we’ve seen a corresponding increase in the demand for power.”

HECO’s all-time high for the island’s energy use was 1,327 megawatts, which occurred Oct. 12, 2004.

Relief from the current muggy weather won’t happen soon for Hawaii residents as the National Oceanic and Atmospheric Administration reported Thursday that El Nino conditions are likely to continue through the winter before weakening in spring.

Air conditioning businesses reported that demand has followed the record-breaking temperatures.

Cosco Air Conditioning and Refrigeration said demand for 2015 has exceeded projections by 50 percent; in August it was 160 percent over what the company was expecting.

The use of these appliances can have a dramatic effect on resident energy use.

“Residents who don’t use an energy-efficient unit may rack up a higher electric bill to survive this heat,” said Shan Wirt, spokeswoman for Hawaii Energy, a ratepayer-funded energy conservation and efficiency program.

For cooling, air conditioning units are the most demanding.

The energy usage difference between an energy-efficient ceiling fan and window air conditioning unit can be about 62 kilowatt-hours per month, said Hawaii Energy. At 30 cents per kilowatt-hour, it is an $18.60 difference per month.

For July and August, Hawaii Energy said it saw a 400 percent increase in air conditioning rebate participation compared with the two previous months.

Hawaii Energy’s rebate program includes, among other deals, a $50 rebate for purchasing a qualified window air conditioner and trading in an old, working window unit or portable air conditioner unit for recycling.

For more information on rebates from Hawaii Energy, see hawaiienergy.com/for-homes/rebates/hvac.