Water year 2026 is off to a two-tiered start, with snowpack at higher elevations significantly outpacing snowpack at lower elevations. Two trends since October 1 were certain. Temperatures were well above average, and precipitation has been abundant. The map below shows the 70 out of 96 SNOTEL stations in Montana that experienced either their 1st or 2nd wettest December on record in blue. Unfortunately, the rain line was too high to see much of that precipitation fall as snow at low elevations. Additionally, many SNOTEL stations lost several inches of snow water equivalent (SWE) during the unseasonably warm December 10-13 atmospheric river. At higher elevations, where precipitation fell as snow, SNOTEL sites reported well above average snow water equivalent on January 1. Only the snowpack of the Lower Clark Fork, Powder and Tongue basins remain below normal. Every other basin remains near or above normal for this time of year.

Despite a strong start and a handful of minor storms later in the month, snowpack accumulation slowed in January. Montana snowpack’s snow water equivalent (SWE) ranges from around 45-100% of median for February 1, with the Bears Paw Mountains reporting the lowest percentage, and the basins centered around Yellowstone National Park reporting the highest.

Following a slow start to the snowpack accumulation season, snowy weather during the last week of December and first week of January has drastically improved snowpack conditions. The largest snowfall accumulations occurred in western and northwest Montana, while northern Wyoming basins benefited less from the late-December storms. Despite recent improvements, snowpack percentages remain slightly below normal across most of Montana. The exceptions are northwest Montana and the Bears Paw Mountains which have a slightly above normal snowpack. For the rest of the state, the lack of snowfall during October and November created a deficit that will require sustained snowfall to overcome.

Snowpack accumulation during January varied drastically across the state. In northwest Montana, an above normal January 1 snowpack dropped to below normal after receiving minimal precipitation the second half of January. In contrast, a strong storm system hit central Montana resulting in well above normal snowpack for February 1. The Gallatin, Powder, and Tongue River basins had above normal precipitation during January, but following a slow start to the season the snowpack in these regions is still below normal. Consistent smaller storms across the rest of the state resulted in below to near normal precipitation, which maintained the below normal snowpack conditions from January 1. 

February was a month of steady snow accumulation in Montana. Most basins have near to below normal snow water equivalent (SWE). Colder temperatures for most of the month ushered in winter weather. The warm and sunny conditions near the end of the month slowed snow accumulation in most areas. Most snow courses and SNOTELs had SWE values in the range of 2” below to 1” above normal at the end of February. The map below shows snow measuring station departure from median SWE at the end of February. Some snow monitoring stations in the northwest Montana and the Rocky Mountain Front have larger SWE deficits. Dry January conditions and a slow start to water year precipitation accumulation allowed enough time for SWE deficits to increase. However, with snow accumulations in February the deficits decreased, and SWE values got closer to normal. Deficits also exist in soil moisture across the state. Most of the state remains in drought conditions, despite the steady snow accumulations.

March started off with little to no snow accumulation in most areas. The lull in accumulation gave time for snow water equivalent (SWE) deficits to increase in some locations. Near the middle of the month most areas began accumulating snow once again. By the end of the month most stations had SWE values that climbed closer to normal. Most stations in the southwest part of the state have SWE values close to normal. The northwest part of the state and the Rocky Mountain Front have more stations with below normal SWE. Deficits from earlier in the winter persist in these areas.

April ushered in spring conditions in Montana. Variable temperatures and weather effected snowpack across the state. Many sites experienced a halt to snow accumulation during this time. Scattered winter storms caused accumulation to momentarily restart at certain sites. Accumulation continued at higher elevations throughout the month. Widespread melt occurred at lower and mid elevation stations. With some stations melting out completely. Higher elevations experienced some snowmelt with SWE beginning to decrease near the end of the month.

With summer in Montana just around the corner, warmer than normal May temperatures ushered in the seasonal transition and spurred rapid snowmelt. May precipitation varied drastically across the state. Northwest Montana and the Gallatin, Upper Yellowstone, and Bighorn basins had below normal May precipitation. Southwest, central Montana, and the Powder and Tongue basins experienced near to above normal May precipitation. This brings the water year precipitation to near normal across most of the state, and below normal in northwest Montana. The warm temperatures swiftly shepherded in spring runoff. Snowpack across Montana is 25%-70% of median, well below normal for June 1. This is a drastic drop from May 1 where snowpack was largely 75%-110% of median. One exception is the Bighorn Mountains, where June 1 snowpack in associated basins is 75%-120% of median.

Warm temperatures and lack of precipitation over the last couple months have resulted in a bleak start to the seasonal snowpack in Montana and northern Wyoming. Precipitation since October 1 has mostly been well below normal. As a result, the snowpack is currently about 30-60% of what it normally is this time of the year, except for part of the southern Absaroka and Wind River Mountains. Currently many NRCS snow monitoring stations in the region are reporting their lowest snowpack on record. Additionally, temperatures have been significantly warmer than normal during the last two months, as a result the snowpack has experienced some melt.

An early January storm brought hope that normal winter weather had finally arrived. After record setting cold temperatures settled in mid-month for about a week, well above normal temperatures accompanied by dry weather returned and persisted during the last two weeks of January in all but the northern Flathead and Kootenai River basins.
Most basin wide snowpack percentages haven’t changed much since January 1, and are still well below normal. Above normal precipitation was needed to make significant gains on the snowpack deficit, yet January precipitation was below normal in all but the Kootenai River basin. Currently, all snowpack percentages are below normal.

Following an exceptionally slow start to the water year, winter weather arrived in February and provided much needed precipitation to the region. Precipitation last month was above normal in all but the northern Bighorn Mountains. Snowpack percentages have increased in all basins, but overall, the snowpack remains below normal. The recent improvements were timely, but there are only one to two months remaining in the normal snow accumulation season and more snow is needed.

Given the lack of precipitation from November through much of January in Montana, above normal precipitation was needed over the last couple of months to begin to catchup on snowpack and precipitation. February provided well above normal precipitation to nearly all of Montana. Basins such as the Jefferson and Upper Missouri received over 150% of normal precipitation during February and those weather patterns continued into the first week of March across much of Montana. What seemed to be the beginning of a potential recovery tapered off after the first week of March in many basins. Overall precipitation was above normal in southwest and southern Montana, but mostly below normal elsewhere.

Well above normal precipitation during April was needed given the meager snowpack conditions experienced this year. Total monthly precipitation was above normal last month in the Powder and Tongue River basins, but was not widespread across Montana. A couple mid-month storms did provide significant snowfall, but April is typically a wet month in Montana, and total precipitation last month did not meet that standard. April precipitation was overall about 65-80% of normal with a couple of isolated locations that were higher. For example, the Gallatin and Bitterroot received about 90-95% of normal April precipitation. Spring weather in Montana can be highly variable, with a storm that is currently adding to the snowpack as this report is being prepared. While this is exactly what is needed, this one storm alone will not likely make up for the water year precipitation deficit across most of western Montana. Water year precipitation is 75-85% of normal for most of the state. Northern Wyoming basins and the upper Madison have fared slightly better and are currently at 90-100% of normal water year precipitation.

Summer is fast approaching and as Montana wraps up the 2024 snow accumulation season recent weather helped improve the water supply outlook, however the outlook remains below normal in many locations. Last month brought a mix of snow, rain, and sunshine across Montana. While that is not uncommon weather for this time of the year, some locations did not receive the moisture they needed. The Kootenai, Lower Clark Fork, Jefferson, and upper Madison River basins experienced below normal precipitation last month. All other basins received above normal precipitation, and some of the storm totals were exceptional. Periods of cool weather delayed snowmelt and increased snowpack percentages in many basins. The Gallatin, Smith-Judith Musselshell, Powder, and Tongue saw the largest increases. June 1 snowpack percentages currently range greatly, from well above normal in the Bighorn Mountains to well below normal around Helena and the Rocky Mountain Front.