North Lahontan

Hydroclimate Report Water Year 2019

California Department of Water Resources (DWR) | June 30th, 2020

Water year (WY) 2019 continued to demonstrate effects of climate change with greater variability and more extremes. Hydroclimate extremes presented themselves with atmosp

Water year (WY) 2019 continued to demonstrate effects of climate change with greater variability and more extremes. Hydroclimate extremes presented themselves with atmospheric rivers causing both flooding and heavy snowpack. Before the wet winter and spring months, California experienced a very dry fall in where the devastating Camp Fire started on November 8, 2018 in Butte County. Fall transitioned to into a wet winter with 64 percent of the WY total for the DWR Northern 8-station index falling in the three months of January, February and March. Temperatures went from extreme cold in February to hot in August as the year progressed from winter to summer.

Hydroclimate Report Water Year 2020

California Department of Water Resources (DWR) | August 31st, 2021

Water Year (WY) 2020 continued to demonstrate the climate change narrative of greater variability and more extremes. In both precipitation and temperature, there were ne

Water Year (WY) 2020 continued to demonstrate the climate change narrative of greater variability and more extremes. In both precipitation and temperature, there were new extremes with a very dry February and very hot end to the water year. Late fall precipitation onset continued with the first significant storm of the year arriving in late November. The WY ended with 67 percent of average precipitation statewide and 62 percent of average in the Northern Sierra. For runoff, the Sacramento Basin had 66 percent of average April-July streamflow while the San Joaquin Basin had 58 percent of average. Peak statewide snowpack was 62 percent of average reaching that point in early April with a late season storm providing some offset to the winter’s dryness. February was one of the big stories of WY 2020 with record low precipitation. In a year of extremes, August and September also contributed record warmth for the month including a 130-degree Fahrenheit reading at Death Valley on August 16, 2020. This observation, if verified by the World Meteorological Organization, would be one of the hottest daily temperature maximums recorded on Earth. Several cities set new records for days above 90 degrees as well.

Hydroclimate Report Water Year 2021

California Department of Water Resources (DWR) | December 31st, 2022

Water year (WY) 2021 added to the climate change narrative with extreme dryness leading to record setting drought conditions. In both precipitation and temperature, there

Water year (WY) 2021 added to the climate change narrative with extreme dryness leading to record setting drought conditions. In both precipitation and temperature, there were new extremes with a record dry and warm spring being most notable. Late fall onset occurred again this year arriving in late November starting the seasonal snowpack on very dry soils. The WY ended with 48 percent of average precipitation statewide making it the second driest year in 126 years of record. It was also second warmest for statewide average temperature. For two-year totals, WY 2021 set a record, recording less precipitation than WY 1977. There was only one significant storm in the WY in late January which included low elevation snow and very strong damaging winds. The April 1 statewide snowpack registered 62% of average. Peak snowpack at 64% of average occurred the week before April 1. Runoff from the snowpack was far below expectations due to the dry antecedent conditions and record dry and warm spring. The lack of runoff resulted in the need for emergency drought response measures.

Hydroclimate Report Water Year 2022

California Department of Water Resources (DWR) | October 1st, 2024

Hydroclimate Variability in Snow-fed River Systems

American Meteorological Society (AMS) | June 25th, 2019

Snow-fed river system communities are highly sensitive to climate change because the majority of their water supply is derived from snow. A warmer climate shift

Snow-fed river system communities are highly sensitive to climate change because the majority of their water supply is derived from snow. A warmer climate shifts precipitation phase from snow to rain, altering snowpack dynamics, shifting peak streamflow timing, reducing groundwater recharge, and increasing winter and spring flooding. Warmer spring and summer temperatures further compound these “snow droughts” by increasing evapotranspiration rates and irrigation water demand. This presents critical challenges in managing seasonal water supply and demand engineered for stationary climate patterns.

Hydroclimate volatility on a warming Earth

Nature Portfolio (Springer Nature) | January 9th, 2025

Hydrologic Analysis of Mojave River Basin, California, Using Electric Analog Model

U.S. Geological Survey (USGS) | August 18th, 1971

Hydropower capacity factors trending down in the United States

Nature Portfolio (Springer Nature) | June 27th, 2024

Identifying the Amount of Wastewater that is Available and Feasible to Recycle in California

Water Research Foundation (WRF) | July 24th, 2023

Impact of current and warmer climate conditions on snow cover loss in burned forests

American Association for the Advancement of Science (AAAS) | September 17th, 2025

Wildfires are increasingly burning in snow-dominated watersheds and can alter snowmelt dynamics. However, the spatial variability of snow cover loss in burned forests has

Wildfires are increasingly burning in snow-dominated watersheds and can alter snowmelt dynamics. However, the spatial variability of snow cover loss in burned forests has been under characterized. Here, we use remotely sensed snow data to show that, under average winter conditions, snow melts earlier in the first year postfire in 99% of the snow zone. Postfire snow cover loss is more extreme in relatively low-elevation, warm environments compared to that in high-elevation, cold regions. Under +2°C of warming, 73% of the snow zone would experience more extreme earlier postfire snowmelt compared to historically average conditions. Regions with the largest shift earlier in postfire snowmelt timing under average climate conditions also have the largest shift earlier in postfire snowmelt under +2°C warming. The spatial variability in postfire snowmelt timing and exacerbated impact in projected warmer winters affect ecosystem water availability, snow albedo feedbacks, and snowmelt runoff forecasting essential to water resource management.