Temecula could hit 100 degrees by Friday, Oct. 2, and stay there through the weekend as a long-duration heat wave settles over Southern California.

The National Weather Service warned Tuesday, Sept. 29, that triple-digit heat is likely to persist into the second week of October across the Inland Empire. As we reported Sept. 28, the city was already bracing for a hot weekend. The updated outlook is longer and more severe.

The NWS point forecast for Temecula, updated at 12:21 p.m. PDT Tuesday, projects these highs through Oct. 6: Wednesday, 88°F; Thursday, 95°F; Friday, 100°F; Saturday, 100°F; Sunday, 99°F; Monday, 98°F; Tuesday, 97°F.

Overnight lows offer little relief. The forecast shows temperatures around 71°F on Friday, Saturday, Sunday and Monday nights. Those lows could tie or break daily record-high minimums for valley locations, the NWS said.

High pressure moving in from the Great Basin of Nevada and Utah will begin dominating weather patterns by Thursday, according to Patch, which reported on the extended forecast. Tropical Storm Odalys and Hurricane Polo near the Baja California peninsula are keeping temperatures cooler through Wednesday.

Peak daytime highs across the broader Inland Empire are projected to reach 98 to 105 degrees Friday through Sunday, creating what the NWS called widespread moderate to major HeatRisk conditions.

Weekend temperatures in the western valleys could run as much as 15 to 20 degrees above average, the weather service said.

The heat may not end there. One extended-range model indicates well-above-normal temperatures could persist through the first two weeks of October, MyNewsLA reported. The NWS said heat-related advisories or warnings are all but certain for the period. There is a 30% to 40% chance highs could climb to 100 to 110 degrees in Southern California valleys.

Offshore winds add another concern. The NWS expects weak easterly gusts of 25 to 35 mph over the weekend along coastal mountain slopes and inland valleys, raising fire-weather risk during an already dry season.

The weather service advised residents to stay hydrated, limit strenuous outdoor activity during peak afternoon hours, and check on vulnerable neighbors and pets.

Temecula residents can sign up for emergency alerts through the city's Temecula ALERT system or the county's Alert RivCo system. Cell phones and VoIP lines must be registered separately; landlines are enrolled automatically. The city's Office of Emergency Management can be reached at 951-693-3971.