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So Begin Phoenix’s 90° Days

31 Mar 2018, 5:24 pm

Phoenix, Arizona officially had its first 90° high temperature of the year Saturday. Only about 160 more of those to go!

(Caption: IT’S HOT! 🌵 Phoenix, AZ has officially hit 90° for the first time this year. Phoenix usually sees temperatures in the low 80’s this time of year.)

So far Saturday, the unofficial high temperature in Phoenix hit 91 degrees. Once the day is complete the National Weather Service will send out a climate report with the official high. At 91 degrees the high temperature is (so far) 10 degrees above the average of 81 this time of the year, but just short of the record for the date of 95 degrees set on March 31, 2015.

Observed high temperatures (unofficial) on Saturday, March 31

Hitting 90° at this point in the year is not too unusual for the Phoenix area. The average day Phoenix hits 90° or hotter is April 3. Thus, this year’s stat comes just a few days earlier than average. The earliest 90° day was February 17, 2016 and the latest was not until May 12, 1912.

The annual average number of times Phoenix hits 90 degrees in any given year (right) compared to this year’s tally *so far* at 1!

Phoenix spends about half its year at or above 90 degrees. For instance, the chart above shows that the city averages 164 days out of each year getting to 90 degrees or hotter. This year’s tally is one, but it’s not likely to remain at that number for long.

Forecast high temperatures (red line) and low temperatures (blue line) for Phoenix, AZ between Sunday, April 1 and Friday, April 6, 2018

Based on the forecast it appears we’ll have more of the same kind of temperatures heading our way across southwest Arizona for the beginning of April. In fact, while much of the nation will be gripped by colder-than-average weather to begin the month, the Southwest will likely stay warmer.

The likelihood of colder (blue) or warmer (orange) than average temperatures between April 6 and 10
The likelihood of colder (blue) or warmer (orange) than average temperatures between April 8 and 14

Since this is just the beginning of the 90 degree days, how long does it last? Well, hang on for a long ride. Phoenix’s average final 90 degree day for the calendar year is October 25th. The earliest it occurred was on September 28, 1916 and the latest it occurred was all the way to November 15, 1999.

For WeatherNation, Meteorologist Steve Glazier