Developing El Niño is Already Atypical


The latest 3-month RONI (Relative Oceanic Niño Index) for April-May-June is at +0.47, just shy of the threshold for a weak El Niño. But looking at the sharp upward trajectory (and latest monthly values) of the current event, it is obvious we are headed much higher.

Comparing it to the 7 previous Strong and Very Strong El Niños, this year is starting lower than any of the previous events at this point in the year, and the only one that transitioned from La Niña. But what does all this mean in terms of the developing El Niño and, more so, on what the actual impacts will be? Stay tuned.






 






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Posted

2025-2026 California Rainfall Season in Review


 

Today marks the end of the California rainfall season, with the overall picture of near-normal rainfall for most of Northern California, a bit above normal for Central California, and mostly well above normal for Southern California. Statewide, with the exception of Pine Flat Reservoir, all of the major reservoirs are above their seasonal averages. And of note, this past winter was a Weak La NIña, and the CPC Winter Precipitation outlook reflected a "typical" La Niña pattern of drier than normal in SoCal! 

Links:
https://ggweather.com/ca2025rain.htm
https://cdec.water.ca.gov/resapp/RescondMain
https://ggweather.com/enso/roni.htm
https://www.cpc.ncep.noaa.gov/products/archives/long_lead/llarc.ind.php


Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com



 






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Posted

Strong & Very El Niño and California Precipitation

Strong & Very El Niño and California Precipitation

An updated and more detailed climatology of California Precipitation during Strong and Very Strong El Niño events can now be found at https://www.ggweather.com/ca_enso2026/ca_elnino_strong.html .

The climatology for all El Niño events has also been updated and improved at https://www.ggweather.com/ca_enso2026/ca_elnino.html

It would be relatively straightforward for someone to do similar climatologies for the other western states using the Western Region Climate Center’s State Climate Tracker page at https://wrcc.dri.edu/my/climate/tracker. I would be happy to discuss and share the Excel template that I developed.

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com

Posted

El Niño - Some Context for California Precipitation this Winter

El Niño - Some Context for Preciptation this Winter

 

The NOAA Climate Prediction Center (CPC) has switched into "El Niño is here" mode, with a  63% chance of a very strong El Niño  (i.e., RONI > +2.0°C) during November-January. But just knowing what the strength of El Niño does not guarantee a particular outcome; it only tips the scale. Looking at past seven strong and very strong El Niño events, at least one year had below normal rainfall in California. (https://www.ggweather.com/ca_enso2026/ca_elnino.html)


And El Niño does NOT necessarily translate to extensive flooding in California.  Of the 13 largest flood damage years since 1950, only 4 have been El Niño years, 4 La Niña, and 5 neutral. And when you look at the Very Strong El Niño of 1997-98, it only ranks at #13, because even though many parts of the state had nearly double their normal rainfall, it was spread over about twice the number of normal rainy days. For example, SF had 47.22” vs a normal of 22.89”, and 119 days vs a normal of 71 days. See https://ggweather.com/enso/calif_flood.htm

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com

Posted

Tomorrow is NATIONAL HEATSTROKE PREVENTION DAY - May 1, 2026


 

Tomorrow, Friday, May 1, 2026, is National Heatstroke Prevention Day. It's a day to raise awareness about the hazards of children dying due to heatstroke inside hot cars. Please take a moment to check out and SHARE the materials below and those at NoHeatstroke.org. Thanks for any assistance in helping to save young, precious lives!

Sadly,
Jan

Jan Null, CCM
Adjunct Professor of Meteorology
San Jose State University
jnull@noheatstroke.org   
Web: https://noheatstroke.org 
Facebook: https://www.facebook.com/noheatstroke/







 

Posted

California Precipitation and Water Supply


Despite the recent gnashing of teeth about the relatively dismal snowpack reports, California's total precipitation and reservoir storage are tracking mostly at or above normal. April's storms have kept the important Sierra Nevada and Cascade watersheds at or above normal, and these indices account for both rainfall and snowfall.  A summary of the 154 largest reservoirs in the state shows them to be at 118% of their April 26th historical average.






Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com


 

 

Posted

California Tornadoes


Following yesterday's EFU tornado near Vina, in the northeastern Sacramento Valley, there were several media comments/inquiries along the lines of "I thought California doesn't get tornadoes".  Yes, on average 6.4 tornadoes per year! I have updated the  California Tornado Climatology at https://ggweather.com/ca_tornado.htm. It contains a database of all 487 tornadoes recorded in California from 1950 through 2025. 

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com






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Posted

El Niño Update

IMPORTANT NOTE for Twitter (X) followers: My @ggweather account got hacked last week. I am now @ggweather2026. Please follow and share. Thanks.

As expected, NOAA CPC issued its final La Niña Advisory and has gone into El Niño Watch mode. (https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml)  Their consensus modeling would have the best odds of a moderate-to- strong El Niño next late Fall and Early Winter.

But even knowing what the strength might be, does NOT necessarily foretell the temperature and precipitation outcomes. Case in point, with this year's La Niña the expectation was for Southern California to be drier than normal this winter. Instead, it is mostly 100% to 150% of normal!

And finally, there is no such thing as a "Super" El Niño! Just like the "Godzilla" El Niño of 2015, it is clickbait hyperbole. Please refrain.



Posted

Latest ECMWF ENSO Plume Hyperbole

The issuance of the April ECMWF SEA5 Niño 3.4 anomaly forecast has set off a whole new wave of hyperbole about a doom-and-gloom “Super El Niño”. But, in my opinion, that needs a lot of context:

  • The ECMWF SEA5 model anomalies are still based on the 1981-2020 climatology, which is cooler than the updated 1991-2020 climatology being used elsewhere. It is also not the new Relative Oceanic Niño Index (RONI).

  • A review of the April plumes for the past 7 years shows a pretty consistent “warm bias” versus the observed ONI (i.e., black dotted line).

  • But per this and other models, an El Niño does look likely. The strength is less so! However, even with this knowledge, the impacts of whatever El Niño strength occurs are far from clear, especially given previous events. Caveat emptor.


Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
 

 








Posted

ENSO Precipitation and Temperature Climatology Updates

 

ENSO Precipitation and Temperature Climatology Updates
With the advent of the Relative Oceanic Niño Index (RONI, https://ggweather.com/enso/roni.htm) I have updated several of my previous precipitation and temperature ENSO-related climatologies. The cautionary perspective that these products allow is that the impacts of an "average" ENSO event are really made up from a broad range of actual widely different events and that there is no "typical" event. 

El Niño and California Precipitation: By the Numbers 
https://www.ggweather.com/ca_enso2026/ca_elnino.html, https://www.ggweather.com/ca_enso2026/ca_lanina.html
I have added data for the 3 Sierra Nevada Precipitation Indices, as well as the maximum and minimum for each ENSO category at each location. Similarly, the La Niña site has been updated.

US Winter ENSO Anomalies maps have also been updated.
https://ggweather.com/enso2023/us_elnino_precip.html, https://ggweather.com/enso2023/us_elnino_temp.html, https://ggweather.com/enso2023/us_lanina_precip.html, https://ggweather.com/enso2023/us_lanina_temp.html)

Main El Niño and La Niña Resource Page: https://ggweather.com/enso.htm
 
Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com

Samples:




 

 

Posted