Arizona Weather Force has issued the May 2025 Long Range Update to the Southwest United States Monsoon, effective June 15th through September 30th, 2025.
As stated months ago on social media, I now have the strength and focus to issue the FINAL Monsoon Update …
At the current time, La Nina is fading fast to neutral conditions, which is neither El Nino or La Nina. This is otherwise called a La Nada. Current atmospheric profiles for this time of year do show interesting aspects, with cutoff systems through later May and into the first half of June, with temperatures swings from below normal to above normal along with it. This is known as a see-saw pattern.
The monsoon season is designated by a static date system, which starts on June 15th and goes to September 30th. This is the system we go by now, not the three day of 55+ dewpoints in Tucson. With that being said, long range pattern suggests that the monsoon will start at the end of June, which makes this article being one month out from my start date.
Contradictory to last year’s monsoon pattern, numbers do show a major increase in storm values. This would be due to the fact that the Eastern Pacific Ocean Hurricane Season looks to be above normal this year. When Hurricanes form down there south of Cabo San Lucas and West of Mainland Mexico, these tend to shove moisture and outflow boundaries to the Western Mexico Mountains, southeast of Arizona. As those severe storms along that range form, outflow shows northwest along them and eventually these dynamics enter Arizona through Pinal, Santa Cruz, and Cochise County. Values for this pattern to happen for the heart of the monsoon season will be on the higher end.
With that being said, here at Arizona Weather Force, this season will be going back to the forecast images of hail, wind, severe risk, along with issuing the appropriate severe thunderstorm, flood, and/or tornado watches that will be needed. I’ll be on standby for when the storms are about to begin, but for now just endure the pre-monsoon heat that signals the coming events as we dig deeper into Summer.
Raiden Storm
Master General Meteorologist