PHOENIX — After a wet El Niño winter and spring, Arizona is drying out again.
Our monsoon rainfall has been dismal so far and it’s looking dry as we wrap up August, too.
El Niño is officially over. Sea-surface temperatures in the Pacific ocean near the equator are cooling and now we are in neutral territory – meaning no El Niño or La Niña.
So how will that impact our weather here in Arizona? It’s complicated and it really depends on the season.
El Niño and La Niña have a more direct impact on winter weather than summer weather. That’s because steering winds high in the sky that drive storms around our atmosphere are stronger in the winter.
During the summer, our weather in Arizona is dominated by high pressure and monsoon flow from the south. That flow can pull in moisture from tropical storms in the Eastern Pacific or Gulf of California, which may be more abundant during El Niño summers. Those tropical systems can bring big rain storms into Arizona late in the monsoon season and help beef up our rainfall numbers. So, switching away from El Niño and into neutral conditions means we don’t have a clear indicator as to how the rest of the monsoon is going to pan out.
The Climate Prediction Center shows equal chances of either above normal or below normal rainfall across Arizona through October.
Heading into winter, there is a slight chance El Niño could redevelop, but it’s more likely we’ll stay in neutral conditions, which means we once again do not have a clear indicator as to how our winter weather will play out.
Typically in Arizona, El Niño winters tend to be cooler and wetter than normal and La Niña winters tend to be warmer and drier than normal.