A heat wave that has simmered in parts of the Southwest since the spring was expected to spread into the central and eastern parts of the country during the last week of July, forecasters said Sunday.

«For much of July, hot and dangerous conditions have been normal in parts of the West, Texas and Florida,» the National Weather Service said in a forecast discussion. «These summer conditions will build and expand in the eastern two-thirds of the country this week, beginning in the north-central states and plains.«

Federal meteorologists have issued excessive heat warnings and advisories for a wide swath of the US, including parts of California, Utah, Nevada, Colorado, Oregon, Idaho, Wyoming, Nebraska, the Dakotas, the desert Southwest and Texas, as well as the southern tip of Florida.

Three high-pressure systems of the type associated with hot weather were expected to move over the interior West, Midwest and Northeast and Florida, according to the weather service.

The geographic spread of the heat wave through at least Wednesday could be tempered by thunderstorms expected in the mid- and southern Atlantic and along the Gulf Coast, the weather service said.

NASA reported on July 13 that the past month marked the hottest june registered for the planet. Last week, the director of the agency’s Goddard Institute for Space Studies, Gavin A. Schmidt, told a news conference that July is likely to be the hottest month on record.

Schmidt also said that 2023 could pass as the fourhottest year on recordwith the possibility that it could ultimately be classified higher as a new El Niño releases greenhouse gases and provides a warming influence for the American West.

The National Park Service has reported that at least four visitors to the Southwest are suspected of succumbing to heat-related deaths since early June.

The most recent was reported Tuesday after Steve Curry, 71, of Los Angeles, collapsed in 121-degree heat at Death Valley National Park, according to the park service.

The weather service in Phoenix said Sunday that the city’s record streak of high temperatures above 110 degrees continued into its 24th day. The high was 114.

Maricopa County has counted at least 12 heat-related deaths since the warm months began in April. Additional deaths were being investigated to determine if they were heat related, according to a county report.

Also on Sunday, Salt Lake City registered a temperature of 104, tying its record for the date, federal meteorologists said.

Miami recorded a high of 98, surpassing its record of 95 to date, the weather service said. Monday will be the 44th consecutive day in Miami with a heat index temperature, a «feel-like» figure measured by including humidity, above 100 degrees, forecasters said.

Fort Lauderdale tied his record for the date, 95, according to the weather service.

Continuous heat began in Texas in mid-June, before the summer solstice on June 21.

Scientists say the prolonged summer heat is consistent with the effects of global warming, which they say is creating more intense, frequent and prolonged episodes of extreme weather in much of the world.