10/6/25 Forecast Discussion

The 2025-26 Water Year has officially begun. After our early season storm, forecast models are agreeing on an unsettled pattern in the extended range. Just how unsettled? Read more to find out!

10/6/25 Morning satellite image of the Eastern Pacific and Western U.S.

2024-25 Water Year Recap

Northern Sierra 24-25’ Water Year summary (pink line)

Overall, last water year was about as average as it could get. Clocking in at 56.6 inches (3.4 inches above the climatological average), residents in the Reno-Tahoe area were treated to an “anomalously” average winter.

After an above-average November and December, the tap shut off in January for our peak precipitation season. However, significant storms in February and a flurry of weaker storms throughout the spring brought us to average.

Snow water equivalent (SWE) during the climatological SWE peak (April 1st) for the 24-25’ water year

Snowfall around the snowpacks that feed into rivers in and around our region was a mixed bag last year. The central Sierra had slightly above average snowfall while most of the northern Sierra, southern Sierra, and foothills were below average. Anecdotally, this was one of the few winters in recent memory that didn’t feature a respectable snowfall event in the valley floor.

Water Year 25-26’ (so far)

Percent average precipitation totals since the beginning of October, which is the beginning of the water year

During the first couple of days of October, we had an unseasonably wet storm kick off our water year in a positive way. Subtropical moisture was drawn towards NorCal in with weak IVT, although spillover into the lee side valleys was easy to come by. The Reno airport received nearly a half inch of rain while surrounding foothills barely missed out on an inch. By early October standards, this was a decent precipitation event.

However, significant early water year precipitation events are not an indicator of if the rest of the year will have the same luck. In October 2021, NorCal and Western Nevada had one of the wettest Octobers on record due to a family of ARs making landfall late in the month. Later in the year, January 2022 became one of the only Januarys to not receive a single drop of precipitation for many Western Nevada and Central Sierra locations.

Seasonal forecasts (predictions that extend into the monthly range) are not useful in our region due to the lack of teleconnection reliability that some other areas in the country are more fortunate to rely on. This is why we have to take a look at our weather here in Reno-Tahoe week by week.

Monday - Wednesday

FV3’s take on the warm temperatures during Wednesday afternoon

Our pattern will change to being less heavy-layer friendly as temperatures in the region rise into the mid to upper 70s in the valley. Winds will also be light and variable during these next few days. Skies will remain nearly perfectly clear from now until Wednesday afternoon when high clouds increase as a low pressure is projected to deepen offshore the OR/WA coast. Enjoy these autumnal days with a flavor of summer in them, they won’t stay around long.

Thursday - Sunday

A note to make during our transition seasons (Spring/Fall) is that forecast models are shockingly unreliable in the medium to extended time range (>3 days). Despite this background uncertainty, every reliable global model ensemble has a deep trough in roughly the same location. I would feel confident in a pattern change with the expectations being limited to precipitation is likely to fall in the Western U.S. somewhere, temperatures will cool off, and wind gusts will rise. Concerning the specific impacts to the Reno-Tahoe region, too much to make a decisive forecast is to be determined.

In short, after a brief summer flashback, we'll be back to feeling fall-like by the end of the weekend!