It’s tempting to say that 2016 was an unusually warm year in Tucson, but above-average temperatures are becoming common.
Tucson’s average temperature of 72.1 for 2016 tied 2014 for the warmest year in 121 years of record-keeping by the National Weather Service.
Five of the current decade’s seven years now sit in the top 10, and eight of the 10 warmest years have occurred since 2003.
That jibes with regional climate records. The period from 1950 to 2013 “has been hotter than any comparably long period in at least 600 years,” according to “Our Changing Climate,” a report compiled by 300 climate experts for the U.S. Global Change Research Program.
“The decade 2001-2010 was the warmest in the 110-year instrumental record, with temperatures almost 2°F higher than historic averages, with fewer cold air outbreaks and more heat waves,” said the report’s section on the U.S. Southwest.
The year began warm, said Mike Crimmins of the University of Arizona’s Climate Assessment of the Southwest.
Crimmins said the region “expected to be drowning in El Niño,” the warm-water phenomenon in the Pacific Ocean that usually brings winter rain to the Southwest.
January had average temperatures and more than twice normal rainfall, but February and March were dry and unseasonably hot. “We started off the year super warm. The highs and lows were sort of off the rails.”
February was 5.8 degrees above average and March was 4.9 degrees higher.
The hot year produced some, but not all, of the expected consequences.
In June, during what Crimmins called “an epic heat wave” across the region, three hikers died in the Tucson area as temperatures spiked in the first and third weeks of the month, reaching a yearly high of 115 degrees in Tucson on June 19.
June heat was mitigated late in the month by the early arrival of monsoon thunderstorms.
Moisture from the monsoon also put an early stop to the summer wildfire season, which had begun to look scary.
The productive monsoon made up for sparser precipitation in winter and early spring.
Rainfall totals for the year were slightly above normal — 11.81 inches at the official gauge at Tucson International Airport, with 7.4 inches falling during the monsoon period of June 15 to Sept. 30. Normal for the current climate period is 11.59 inches per year.
July temperatures were also above normal. “None of the daily averages screamed ‘record,’ but pretty much every day was above average and the overnight temperatures were so warm,” Crimmins said.
Then came the hottest fall on record. The hottest October ever topped the average by 6.5 degrees.
Crimmins said those who attribute the temperature rise to El Niño, a warming world or the heat-capturing mass of the urban environment, are all correct.
“It’s a mix of all three and probably more of a mix of El Niño and the longer-term temperature trend,” he said. “That longterm trend is the dominant signal.”
That is reflected in the historical record for Tucson. Average temperatures rose each decade from 1900-09 to 2000-09, from 66.6 degrees to 71 degrees.
Meteorologist John Glueck, who compiles climate data for the National Weather Service in Tucson, said the trend is established.
“We’re just a warming planet right now and we just have to expect higher temperatures.”
Glueck said Tucson set or tied 19 record high daily temperatures during the year and recorded only seven days when the temperature hit the freezing mark.
On the plus side, it was the first two-year period of above-normal rainfall since the early ’90s, Glueck said.