ALAMOSA — “For the April, May, June seasonal outlook in Colorado, we have pretty high confidence that it’s going to be warmer and drier,” said Russ Schumacher, Colorado State Climatologist in a recent presentation to water users in the San Luis Valley. 

Schumacher, who is also a professor at Colorado State University Department of Atmospheric Science, was one of the featured speakers at the 2025 Salazar Center State of the Rio Grande Basin Symposium on the Adams State University campus. 

His explanation of how “warmer” and “drier” are closely connected provided a clearer understanding of “how temperature and precipitation fit within a changing climate”. 

Schumacher began with the basics. “The topography of Colorado is a big driver of climate,” he said. “From the eastern plains to the river valleys, valleys on the Western Slope to the San Luis Valley surrounded by mountains, there are huge variations in climate over a distance that isn’t that great. Precipitation in a year is about seven to eight inches in the San Luis Valley versus 50 inches of snow in the San Juans. But, overall, the San Luis Valley has the most interesting weather in the state.” 

During 2024, the last water year, conditions were “a lot happier.” A water year runs from Oct. 1 to Sept. 30. October of 2023 to September of 2024 was a warm water year - the sixth warmest water year going back to the 1800s. When average precipitation is 10 inches per year, precipitation that is more than two inches above average is a big deal. “Some of the southern places in the valley had the wettest year ever,” Schumacher said. “Alamosa was more than three inches wetter than Denver or Fort Collins. That’s never happened before – they were remarkable statistics.” 

Remarkable as those numbers were, much of the moisture in the San Luis Valley comes from snowpack and, in November of 2024, “one huge snowstorm” got the new water year off to a “wet start with three to four inches of water” from just one storm.  

“SNOTEL [a system of measurement] at Hayden Pass was two inches higher that it has ever been, so there was good reason for being optimistic. But,” he continued, “there has not been much moisture since then.” 

During the winter months of December, January and February, temperatures were extremely warm in the San Luis Valley. February was the warmest February on record with eight days of 65 degrees or higher temperatures. The previous record was five days.  

“Very warm goes along with not having much snow,” Schumacher said, “and that’s especially true in the valley where snow on the ground keeps temperatures down. If there’s a lot of snow cover, it doesn’t warm up as much.” 

And now, a little more than a month later, “the numbers are not good for the Rio Grande Basin. They aren’t good for snowpack which means they’re not good for water supply.” 

In a shift to talking about a climate that is changing, Shumacher says that the two key variables are temperature and precipitation.  

Going back to the late 1800s in the Rio Grande Basin, the number of “warm” days have significantly increased since the 1980s to the 1990s, and that trajectory has continued with 2024 being the third warmest year on record.  

Having temperature records extending over such a long period of time makes predicting temperatures in the future something that can be done with significant confidence. But precipitation is much more complicated with great variability from year to year and decade to decade.  

“There have been lots of dry years since 2000, but they rival dry years from the Dust Bowl,” he said. To have confidence in what conditions such as stream flow and run-off may be in the future, one has to take into account the interaction between precipitation and temperature and the evaporative demand that is the result.  

Schumacher explained this by saying, “When it’s warmer and drier, the air is thirsty for water, so it pulls that moisture out from the soil, the crops, the forests and reservoirs. That air’s thirst for water – that is what we call evaporative demand, and this is how climate change is addressing drought because it’s an issue of hot drought. Yes, drought is partly exacerbated by there being less precipitation but it’s actually the higher temperatures that are most responsible for the dryness because of evaporative demand. 

“So, when an area is experiencing record breaking heat – even the years when there is more than usual precipitation - the water isn’t going to go as far. Likewise, when the temperature is high and precipitation is low, the impact is even worse because of the increased demand for water from the atmosphere.” 

Schumacher wrapped up by saying, “For the April, May, June seasonal outlook, we predict with greater than average confidence that, in the San Luis Valley, it will be warmer and better than average confidence that it will be drier.  

“I know the news isn’t good right now,” he continued, “and this isn’t the impact we want to see. So, take the predictions with a grain of salt. I like to tell people that we’re right more often than we’re not but we’re wrong a lot. Even so, we have pretty high confidence that it’s going to be warmer and drier.”