NewsArizona News


What is up with this monsoon? Where’s all the rain?

Monsoon storms 7-3
Posted at 8:32 PM, Aug 28, 2019
and last updated 2019-08-29 18:50:28-04

It’s not your imagination. This monsoon has been mostly missing in action.

Phoenix is now in the midst of the fourth driest monsoon on record with little more than a quarter of an inch in the last two months.

The rankings are just as bad, if not worse, for other parts of our state.

Both Flagstaff and Show Low are currently in the number one spot for the driest monsoons on record as of August 27.

So why is this happening? It’s complicated, but overall our monsoon flow has had a hard setting up. Typically, high pressure will get positioned near the Four Corners, shifting winds out of the south which bring in our monsoon moisture. But this summer, high pressure has often been sitting over central and western Arizona which blocks moisture from coming in and instead cranks up the heat.

As of August 27, we are now up to 27 days at 110 degrees or more here in Phoenix. We’ve only had five years on record with more.

We’ve also had 11 days where overnight lows didn’t drop below 90 degrees.

All of the top years with the most lows in the 90s have occurred in the last two decades.

So when will this sweaty mess of extreme heat end?

On average, our last 110-degree day is August 26. We’re already beyond that and we’ve got a couple more 110s in the forecast heading into Labor Day weekend. The latest we’ve ever hit 110 degrees was September 19, 2010. At this point, there’s no telling if we’ll see more 110s into mid-September, but we can get some long-range guidance from the Climate Prediction Center. Their outlook shows a good chance of above normal temperatures across Arizona through the end of the monsoon which officially wraps up September 30.

As far as rainfall goes, this monsoon will likely end as one of the driest on record. While there’s still a month to go, we’ve got a lot of making up to do. We typically get between two and a half and three inches of rain during the monsoon season here in Phoenix. The outlook for September shows equal chances of above normal or below normal rainfall, so we’ll just have to wait and see how it all pans out.