Tucson's monsoon plays catch-up with a banner July

June brought almost no rainfall in Tucson, but since the first big monsoon storm hit July 10, rainfall in some places around the metro area has already surpassed average amounts for June and July combined.

The monsoon normally starts in mid-June and brings about 0.15 of an inch of rain to the Tucson International Airport in the last weeks of the month, said Rob Howlett, meteorologist for the National Weather Service in Tucson.

But only trace amounts of rain fell in Tucson this June, and the dry stretch continued through the first week of July.

Now, with several recent heavy rains, the monsoon is surpassing expectations.

“The season just went zero to 60 over the last week in Tucson,” said Michael Crimmins, University of Arizona associate professor of global change and soil, water and environmental science.

As of Tuesday, July 18, the official NWS reporting station had received 2.7 inches of rain since the start of the monsoon, most of which fell within the last week.

“The first day that we saw rain was July 10, and from that point on, we’ve seen seven days (of rain),” Howlett said Monday.

“There was only one day where there was no measurable rainfall at the airport (on July 12).” But other parts of town saw up to an inch of rain that day.

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Even so, the airport is seeing higher-than-average levels of rainfall: 2.7 inches so far this month, compared to the average 2.25 inches for the entire month of July.

Parts of Tucson’s west side received more than 3 inches of rain on Monday, according to Jordan Pegram, meteorologist at the weather service.

Thirty-day rainfall totals provided by Pima County Regional Flood Control maps show above-average totals ranging from more than 5 inches on Mount Lemmon, almost 4 inches in places on the southwest side, and 2 to 3 inches in many parts of the metro area.

“Tucson is winning,” said Crimmins while comparing levels of rainfall around the state during the 2017 monsoon.

There’s far more monsoon action along the Mogollon Rim and in Tucson than in the northwest, southwest and northeast reaches of the state, Crimmins said.

But on Sunday, storms that started along the Rim moved southward and drenched Phoenix around sunset, resulting in the first big storm of the season for the area, said Jaret Rogers, meteorologist at the weather service in Phoenix.

Phoenix Sky Harbor International Airport reported 0.43 inches of rain, but some areas in west-central Phoenix reported up to 3.5 inches Sunday night.