Phoenix endures 144 days of 100-degree heat, breaking long-standing record

A 31-year-old record melted away on Wednesday as relentless triple-digit heat continued to scorch Phoenix for the 144th day this year.

The previous record for the most 100-degree days in a year was set in 1989 with 143 days in total.

When the mercury reached 100 F on Wednesday afternoon, it also tied the record high for the date, which was last reached on Oct. 14, 2015.

The city could tack on a few more days to the already impressive record with high temperatures in the upper 90s to lower 100s in the forecast across the major metro areas of the desert Southwest into the weekend. However, time is ticking for more 100-degree days in the city. The latest that Phoenix has ever recorded a high of 100 F was on Oct. 27.

In a given year, Phoenix Sky Harbor International Airport, the official climate station for the city of Phoenix, typically averages about 102 days where the high temperature equals or exceeds 100 degrees.

The worst of the heat arrived for many across the desert Southwest as early as Tuesday, while the arrival of the worst heat for cities like San Francisco and Redding, Calif., will be delayed until after midweek.

Unseasonably warm conditions are expected throughout most of the southwestern United States this week. However, the desert Southwest will be in the crosshairs for the truly sizzling temperatures.

The hottest conditions through the rest of the week will bake portions of southern Arizona, southern Nevada and inland areas of Southern California. In these areas, daytime high temperatures will generally climb 10 to 15 degrees Fahrenheit above normal levels for the middle of October.

Typical high temperatures across the desert Southwest range from the lower 80s in cities such as Las Vegas to near 90 in cities such as Phoenix and Palm Springs, Calif., to the middle 90s in Death Valley, Calif.

Other cities where record high temperatures are in jeopardy of being tied or broken this week include, but are not limited to, Las Vegas and San Francisco. In Las Vegas, temperatures will flirt with record levels through Wednesday, while records will not be in jeopardy in San Francisco until Thursday and Friday.

Heat of this level will act to increase the risk for heat-related illnesses, especially for the most vulnerable populations. Residents across the Southwest should drink plenty of water and try to limit any outdoor activity to the morning or evening hours to avoid peak heating.

In addition to unrelenting heat, here is another serious threat for portions of the Southwest: high winds.

"Tuesday night into Wednesday, surface high pressure quickly moved inland across the Northwest and strengthened, which created a textbook offshore wind setup," Sojda said. "The strongest winds look to occur later into Thursday morning, when the high over the Northwest will peak in strength."

"The focus of the strongest winds will be in the northern Sierra Nevada and Sacramento Valley into the Bay Area, but the pressure gradient will be just robust enough to get slightly stronger wind gusts over a larger portion of the mountains in Southern California as well," Sojda added.

These strong winds will act in conjunction with other factors including very low humidity levels, no precipitation and extremely dry fuels to create an elevated to critical fire threat across portions of California through Friday.

Where firefighters have made progress toward full containment of large fires, these strong winds may considerably hinder further progress or even act to erase progress altogether. Rapid fire growth is likely to occur in areas impacted by the strongest winds.

Unfortunately for residents across the Southwest waiting for prolonged relief after months of brutal weather, the wait will continue through at least the weekend, as little to no change in the overall weather pattern is anticipated.