You’re not wrong if you felt this year’s monsoon was lacking, but the National Weather Service recently announced exactly how dry monsoon 2020 was. The average monsoon brings Tucson just over 6 inches of rain from June 15 through September. In 2020, we received only 1.62 inches.
This makes 2020 the second driest monsoon since the weather records began in 1895. In fact, 2020 was only .03 inches from being the single driest monsoon ever, an honor that belongs to the 1924 monsoon, which saw 1.59 inches. 1924 and 2020 are also the only monsoons on record with less than 2 inches of rain.
On a monthly breakdown, June generally sees .15 inches, July sees 2.25 inches, August sees 2.39 inches, and September sees 1.29 inches. For 2020, June had no rain, July had .46 inches, August had 1.16 inches, and September had trace amounts.
Luckily, this weak summer rain is not a trend in recent years. While monsoon 2019 also saw below average rainfall, 2015 through 2018 all saw above-average monsoonal rains, with 2017 seeing nearly 50 percent more rain than average.
However, rainfall is only one part of the equation. August 2020 was also Tucson’s hottest month ever recorded since 1895, beating the previous record set by … July 2020. Both months combined to make this summer the hottest in all 125 years of weather records. According to NWS data, this August held a combined average temperature of 92 degrees. This July held a combined average of 91.5. Before these last two months, the hottest average month was July 2005 at nearly a full degree lower.
The average August temperature over the last 125 years is 84.7 degrees, and the average July temperature for the same range is 86.5. These temperatures are not daily highs, but averages over the entire month—highs and lows. And while these last two were the hottest months on average, the maximum temperature recorded on a single day in Tucson was in June 1990 at 117 degrees.
“The trend is for warmer,” said John Glueck, senior forecaster for NWS Tucson. “We’ve had hotter summers for a good period of time now, and that’s something we’ll just have to get used to with a warming climate.”
This article appears in Oct 1-7, 2020.
I doubt if there are any “monsoon” records that go back to 1895. Nobody used that term for Asian winds off the Indian Ocean when my parents were kids in the 1920s or when I was growing up in the 1950s. We called them “SUMMER RAINS” & that was good enough for everybody.
As far as summer rains go, 2020 did seem like one of the worst years.
I got 3.32 inches between Jun 15 and Sept 30. “Monsoon” used to begin based on consecutive days when the dew point was 54 degrees or more. The current definition was instituted in 2008. So you can’t compare monsoons, which started in the 1940s by one definition and 2008 by another.
BTW, in 2010 I got 3.16 inches, less than this year.
Like MMP, summer rainy season works for me.
Actually, it’s very simple and easy to compare monsoons, or summer rains, or whatever you want to call them.
The “traditional” start of the monsoon was predicated on THREE consecutive days of AVERAGE dewpoints of 54 degrees or higher (i.e., averaged over the 24 hours of each day)–i.e., the onset of consistent deep moisture in the form of water vapor in the atmosphere. In an arid climate like Arizona, this could only happen in the context of the annual seasonal high-level wind pattern that pulls moisture up from the south, which is called a “monsoon”, a word that is actually derived from Dutch and has long been accepted as a generic meteorological term that refers to any such seasonal wind pattern that induces precipitation.
The official framework was changed at least in part to provide a consistent temporal framework that would make it easier to compare monsoons. There are indeed (summer) rainfall records that go back to 1895 in Tucson (I have the pdf from National Weather Service), and now it’s a relatively simple task to compare the 2020 monsoon time frame (June 15-Sept. 30) to that of 1895, or any other year since, regardless of dewpoints or traditional onsets or whatever.
And yes, if you look at the period of record, this pathetic NON-soon was the second-worst ever in terms of total precip–1.62″, just barely edging the 1.59″ of 1924. If you take into account the brutal, unprecedented, relentless, record-shattering heat, one could easily make the case that this was by far the most miserable monsoon of the past 125 years, and we’ve really never had anything else that was even close. One wonders how many centuries you’d have to go back to find anything remotely like it…???