Summary of Western US SNOTEL Snow/Precipitation Update Report

Summary of Western US SNOTEL Snow/Precipitation Update Report

Based on Mountain Data from NRCS SNOTEL Sites

**Provisional data, subject to revision**

Data based on the first reading of the day (typically 00:00) for Saturday, September 20, 2025

State/River Basin	Snow Water Equivalent		Water Year-to-Date Precipitation
State/River Basin	# of Sites	Percent of Median	# of Sites	Percent of Median
Alaska	30/62	*	45/62	112
Arizona	20/23	*	19/23	60
California	32/32	*	32/32	99
Colorado	100/105	*	101/105	86
Idaho North of Salmon River	31/31	*	30/31	84
Idaho South of Salmon River	64/65	*	64/65	92
Montana	86/91	*	85/91	89
Nevada	29/32	*	31/32	96
New Mexico	21/21	*	21/21	89
Oregon	73/81	*	74/81	102
Utah	84/90	*	88/90	82
Washington	64/76	*	62/76	81
Wyoming	83/85	*	81/85	90
Arkansas River Basin	6/6	*	6/6	94
Colorado River Basin	103/108	*	105/108	83
Columbia River Basin	253/266	*	251/266	89
Missouri River Basin	45/48	*	44/48	91
Rio Grande River Basin	28/29	*	29/29	91
The Great Basin	100/105	*	103/105	90

-M = Missing data.
* = Analysis may not provide a valid measure of conditions.
N/A = Not available.

Footnotes for median and average:
(##) = If less than 30 years are available, this value specifies the number of years used for the median and average calculations.
Sites with less than 10 years available do not have medians or averages.

If the Basin Index (%) percent value is flagged as potentially invalid,
care should be taken to evaluate if the value is representative
of conditions in the basin.

The SNOW WATER EQUIVALENT represents the depth of water in the snowpack, if the
snowpack were melted, expressed in inches.

The WATER YEAR-TO-DATE-PRECIPITATION represents total precipitation since October 1st, expressed in inches.

Contact your state water supply staff for assistance.

Medians and averages are calculated for the period 1991-2020.

Provisional data, subject to revision.

* Site -- Either: (a) the current value is missing; (b) the median or average for the day is not available or is zero; or (c) for snow water equivalent, the median or average for the day is less than 10% of the maximum median or average value for the year.

* Basin - More than half of the stations for a basin with normals report missing or invalid data.

The basin index is calculated as the sum of the valid current values divided by the sum of the corresponding medians or averages and the resulting fraction multiplied by 100.