March temperatures shattered records in Phoenix and across the West

Last month was the hottest March on record for Phoenix and much of the U.S. West.

Phoenix’s average March temperature of 78.8 degrees was 12.5 degrees above normal and 6.5 degrees hotter than the previous March record set in 2004. The Valley hit triple-digit temperatures earlier than ever recorded and broke daily heat records on 15 days throughout the past month.

Climate scientist Zack Labe, with the research organization Climate Central said the heat wave across the West was unprecedented not only because it struck in March, but because it persisted for weeks.

Research from the organization World Weather Attribution shows the extreme heat throughout the West in March would have been “virtually impossible” without human-caused climate change.

“So far, the observations are showing that these heat extremes are increasing more quickly than our climate models project,” Labe said during a panel discussion with reporters last week.

Labe said the unprecedented heat wave will likely have serious repercussions throughout the West in the months ahead.

“We have dry soils, dry vegetation, we have parched stream flows that are running much lower than normal, all setting the stage for, more likely than not, conditions that are more conducive for wildfires,” Labe said.

Here’s a look at the heat wave by the numbers:

• 12.5 degrees above normal — Phoenix’s average March temperature of 78.8 degrees was 12.5 degrees above normal and 6.5 degrees hotter than the previous March record set in 2004.
• 15 days of heat records — 15 days throughout March broke daily high temperature records.
• 9 days in triple-digits — 9 days in March reached temperatures of 100 degrees or more in Phoenix. Previously, Phoenix had only ever reached 100 degrees in March one time, on March 26, 1988. 
• 45 days early for triple-digits — Phoenix broke the record for the earliest in the year the Valley has ever reached the triple-digits, climbing to 102 degrees on March 18, eight days earlier than the previous record of March 26, and 45 days earlier than the typical first triple-digit day of May 2. 
• 105 degrees — 3 days in March reached 105 degrees in Phoenix, the hottest March temperatures ever recorded in the city. The previous record was 100 degrees.
• 112 degrees — On March 20, two places in Arizona — Martinez Lakes and Fort Yuma — and two nearby California communities reached 112 degrees. That was the hottest March temperature ever recorded anywhere in the U.S.

Climate Central