HARTFORD, Conn. – The mild summer so far has allowed New Englanders to often turn off their air conditioners, helping cut costs with reduced demand for electricity.

An abundance of natural gas and more efficient power plants have helped reduce the wholesale price of energy, a respite from soaring heating costs in the winter, said ISO-New England, the region’s grid operator.

“In New England, we have a tale of two seasons,” said Matthew White, chief economist at ISO-New England.

The average wholesale price in June was 1.96 cents per kilowatt hour, down by nearly 50 percent since June 2014, he said. The decline continued in July, dropping by more than 27 percent year over year, ISO said Tuesday.

Costs are falling for some ratepayers, but it’s uneven among New England states and the lower prices are in effect for only a few months. The U.S. Energy Department said retail prices in New England were higher in June and July than in the same months last year.

Connecticut regulators approved a nearly 20 percent cut, or an average $31 a month, for residential customers of Eversource from July 1 to Dec. 31.

The price for customers of Central Maine Power dropped by more than 13 percent beginning last March 1 and extends through the end of the year. Maine Public Utilities Commission Chairman Mark Vannoy cautioned that the trend may not continue due to strong demand for natural gas in New England and the limited capacity to deliver it.

In Massachusetts, a reduction of more than 20 percent kicked in May 1, but rates climbed more than 30 percent last November, said David Graves, a spokesman for National Grid.

Vermont did not deregulate its power markets and it avoids price spikes and cost-cutting, said Public Service Commissioner Christopher Recchia. “We’re pretty stable here,” he said.

Another factor in lower wholesale prices is a boom in natural gas production, with supplies of shale gas from Ohio and Pennsylvania up 500 percent in five years, White said. New Englanders also have benefited from about 15,000 megawatts of generation added since 1997, with about two-thirds in efficient natural-gas fired generation.

The contrast with winter price spikes is striking. During February’s record cold, for example, demand for natural gas was so high that pipelines serving New England were at or near capacity, driving up the price of natural gas, ISO said.

Greg Cunningham, senior attorney at the Conservation Law Foundation, said the lower prices are partly a function of timing. Utilities in Maine and New Hampshire took advantage of lower prices in electricity contracts negotiated a few months after price spikes pressured Massachusetts utilities and their customers, he said.

“Predicting energy prices is not a game anyone wants to bet our paychecks on, but wholesale and retail prices are lower,” he said.