The odds of having above-normal temperatures will decrease in the second half of our summer.

No, silly, it's not actually going to be cooler.

Starting Monday, the National Weather Service will base those calculations on a "new normal," calculated from the temperature record of the previous 30 years and updated each decade.

On Aug. 1, we'll swap the relatively wetter and cooler '70s for the hotter and drier first decade of the 21st century.

Nationwide, the period of 2001-2010 was nearly a degree-and-a-half hotter than the decade of 1971 to 1980. The difference in maximum temperature was 1.37; minimum, 1.55; and average, 1.46, according to the National Oceanic and Atmospheric Administration, the parent agency of the National Weather Service.

For the 30-year average, the difference translates to about half a degree, averaged across the country, though some places had bigger increases and some regions cooled.

For Tucson, the normal average high jumps from 82.5 to 83.1. The average low rises from 54.8 to 55.8 degrees. The overall average goes from 68.7 to 69.4 degrees Fahrenheit.

"When you see the normal jump by anything above half a degree, that's significant," said J.J. Brost, science and operations officer for the National Weather Service in Tucson.

The fact that the minimum temperatures rose more than the maximum should not be a surprise, Brost said. We live in a constantly urbanizing environment. Concrete and asphalt retain more heat than the dirt and vegetation they replace.

Arizona's decade-long drought conditions also show up in the "new normal."

Normal annual precipitation drops from 12.17 to 11.59 inches.

The bottom line: We can now be hotter and drier and still be normal.

Hope that makes y'all feel better.

On StarNet: View current conditions, the 10-day forecast for Tucson and Southern Arizona, and learn about monsoon safety at


The atmosphere will remain soppy today, with another good chance of thundershowers at a home near yours.

"We're doing pretty good with the monsoon," said J.J. Brost of the National Weather Service in Tucson.

The average rainfall for July is 2.07 inches, and the weather service has recorded 1.62 inches so far at its Tucson International Airport site.

Some areas in and around Tucson have received more than 3 inches so far, while others remain dry.

"We're right back in the thick of things, and for the next week, we'll have pretty consistent thunderstorm activity," Brost said.

Wednesday and Thursday will dry out a bit with only a slight chance of rain, according to the weather service forecast, but thunderstorms will resume in earnest on Friday and through the weekend.

Contact reporter Tom Beal at or 573-4158.