Hazy mountain

Smoke from California wildfires and a low-pressure system made a haze thick enough to obstruct the Santa Rita Mountains from Interstate 19.

Labor Day weekend added to what the National Weather Service had already declared the hottest summer on record, but there's some relief this week as temperatures drop.

As of Sept. 2, the Weather Service reported 86 days at 100 degrees or above recorded at Tucson International Airport – the closest place for official records. Green Valley and Sahuarita don't have approved stations for official record-keeping.

The holiday weekend brought an excessive heat warning and more triple-digit days – five more with Friday hitting 110 degrees.

The record for most triple-digit days is 99, set in 1994. The same year set the record for most days at or higher than 105 degrees – 53 days.

That record fell on Aug. 28, and Labor Day weekend added three more days above 105 degrees.

The Weather Service recorded July as the single hottest month on record with an average temperature of 91.5 degrees. A month later, August was declared the single hottest month at 92 degrees.

August wasn't just 6.7 degrees above normal, it was also 1.8 degrees above the previous hottest August in 1994.

Triple-digit days were constant.

According to the Weather Service's preliminary monthly climate data, only five of the 31 days in August didn't reach triple digits, and the vast majority of the ones that did were above 105 degrees.

And the Climate Prediction Center is already forecasting above-normal temperatures for September and fall.

While the temperatures might be above normal, there is some relief as this week should see them dip well below the triple-digits days that dominated summer.

The Weather Service forecasts Wednesday's high at 90 degrees in Tucson and 88 degrees for Green Valley.

But don't get too excited. Those lulls into the 90s aren't going to last too long.

Meteorologist Kevin Strongman said temperatures should creep back into the 100s this weekend.

"Come back up to the 100s, but it won't be higher than 105 like we've seen this past weekend where it's been blazing," he said.

The Weather Service reported Tucson, Nogales and Safford had record high temperatures on Saturday and Sunday. Tucson and Nogales had record highs on Monday as well.

The mid-week cooling is the product of a cold-weather system moving through the area.

"So, there's a low-pressure center coming down through Nevada into Utah, and it's bringing colder temperatures from there," Strongman said.

The high winds from the system also brought in smoke from California on Tuesday.

Strongman said the smoke should have started to move out Tuesday night as the cold front passes through and make for clearer skies Wednesday.

On Tuesday morning, the Pima County Department of Environmental Quality said air quality remained good since the smoke was high enough to avoid monitors. However, PDEQ said high winds could cause the smoke to move to ground levels.

PDEQ also said the hazy skies could remain in the area until Friday.

And as the skies clear, the heat will return.

Strongman said the Climate Center's forecast for higher-than-average temperatures for September and the fall remain on track. So does the center's rainfall forecast.

"The CPC had put out saying that it would be below normal," he said. "And that's actually looking like it has a very likely chance of remaining below normal for precipitation."

It's not all bad news.

Strongman said seasonal cooling should start in the next few weeks.

"Possibly next week where it starts dropping off," he said. "But we'll still be in the 90s. But it's definitely cooler from last summer, where it's been above 100 constantly."

Jorge Encinas | 520-547-9732