Colorado’s 2026 water year, which ran from October 2025 through September 2026, ended with record-shattering warmth. The Colorado Climate Center has posted its final water-year review. The statewide headline matters in the Eagle Valley because mountain snow and the timing of runoff shape water supplies well beyond the high country.
What a water year measures
A water year begins Oct. 1, allowing winter snow accumulation and the following spring and summer runoff to be considered in one cycle. It is different from a calendar year. The Climate Center’s water-year data uses this October-to-September convention.
Temperature and precipitation also measure different things. A year can be dry because little moisture falls. Extra heat can compound that shortage by reducing snowpack, bringing melt earlier and increasing evaporation and plant demand for water.
Why 2026 stood out
Even before summer, the Climate Center reported that October 2025 through May 2026 was Colorado’s warmest such eight-month stretch on record and its seventh-driest start to a water year. Its May summary put the statewide average 5.1 degrees Fahrenheit above the 1991–2020 average for that period. Those are October-to-May figures, not full-year figures.
In June, Climate Center researchers explained that record warmth had depleted snowpack and increased evaporative demand, adding to pressure on river flows. Their analysis showed why looking only at precipitation could understate the water impact of an unusually hot year.
What the statewide result does—and does not—say about Eagle County
A Colorado-wide ranking does not tell us the exact temperature, snowfall or streamflow at a specific Eagle County location. Conditions vary by elevation, basin and season. Local decisions should use basin snowpack, stream gauges, reservoir reports and water-provider updates alongside statewide summaries.
The useful takeaway is that water planning cannot rely on rainfall or snowfall totals alone. When temperatures run high, the same amount of precipitation may provide less lasting snow and less reliable runoff. Read the Climate Center’s final water-year review for the statewide record and its regional detail.
