2026 National Hydrologic Assessment

Released on March 19th, 2026

Click here to view the 2026 National Hydrologic Assessment

Take an interactive look at the Spring Flood Outlook

National Spring Flood Risk defined by risk of exceeding Moderate and Major Flood Levels

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For an interactive look at the Spring Flood Outlook, please visit the 2026 Spring Flood Outlook Story Map Journal

Executive Summary

The 2026 National Hydrologic Assessment (NHA) offers an analysis of flood risk for spring 2026, summarized at the national scale. This assessment is based on prior late summer, fall, and winter precipitation, frost depth, soil saturation levels, snowpack, current streamflow, and projected spring weather. 

Widespread major flooding is not expected this spring across the Continental U.S. (CONUS), with a normal to below normal flood risk over much of the U.S. This is driven primarily due to an abnormally warm and dry winter over much of the U.S., resulting in low snowpack and dry soils which will help to mitigate flood responses.

While there is a normal to below normal flood risk overall this spring, minor to moderate flooding is expected in portions of the Lower and Middle Mississippi Valleys, the Lower Ohio and Missouri Valleys, portions of the Central and Northern Plains, and the Upper Peninsula of Michigan. Minor flooding is possible over portions of the Northeast and Southeast as well as eastern Texas. In Alaska, spring ice breakup and snowmelt flood risk is forecast to be above normal for the Yukon and Tanana river basins due to above normal snowpack and cold winter temperatures which enhanced river ice conditions. Below normal flood risk is expected in Southcentral Alaska, the Koyukuk River Basin, and parts of southwestern Alaska.

Based on the expected spring flood outlook, hypoxia development in the Gulf of America and Chesapeake Bay is projected to not deviate significantly from seasonal normals. Hypoxic zones directly impact commercial and recreational fisheries. 

For supporting graphics, please visit the NHA Story Map here.

Heavy Rainfall and Flooding

The information presented in this report focuses on spring flood potential, using evaluation methods analyzed on the timescale of weeks to months, not days or hours. Heavy rainfall at any time can lead to flooding, even in areas where the overall risk is considered low. Rainfall intensity and location can only be accurately forecast days in the future, therefore, flood risk can change rapidly. Stay current with flood risk in your area with the latest official watches and warnings at weather.gov. For detailed hydrologic conditions and forecasts, go to the National Water Prediction Service (NWPS) at water.noaa.gov.

Current Hydrologic Conditions (CONUS)

Temperatures over the CONUS this winter (December 2025 - February 2026) have been above normal, with near to below normal temperatures mostly limited to portions of the Mid-Atlantic, Great Lakes, Ohio Valley, and the Northeast. West of the Mississippi River, temperatures were significantly above normal for the winter, with preliminary data indicating that many areas of the Rockies into the Southwest and Great Basin experienced a near record warm winter. 

The precipitation trend for this winter has been for dry conditions with much of the CONUS experiencing below normal winter precipitation. Pockets of normal to above normal precipitation values can be found along portions of the Upper Great Lakes region, the Northern Plains and the Northern Rockies, and along some of the mountains of the West Coast. Preliminary data suggests that portions of the Central Plains as well as the Lower and Middle Mississippi Valley received near record low precipitation this winter.

Snow water equivalent (SWE) values over much of the CONUS are well below normal, with only areas of the Northern Rockies having near normal SWE values. This is due to a combination of a dry winter as well as widespread above normal temperatures. Although there are some pockets of above normal winter precipitation totals in the West, due to the above normal temperatures, much of this precipitation either fell as liquid rain or was limited to higher elevation snow. 

Soil moisture data from the NWS Climate Prediction Center (CPC) suggests soils are dry over much of the CONUS, with isolated areas of above normal soil moisture values in portions of the Northwest and Northern Rockies, the Upper Great Lakes,  and the Northern Plains. Although temperatures have been above normal for the Northern Plains and Upper Great Lakes, soils remain frozen in these areas, thus locking this moisture in place until soils thaw. 

Despite the dry winter, 28-day average observed streamflow averages over much of the CONUS remain near normal as late February into mid-March is climatologically a period of lower streamflows. For many areas of the Gulf Coast, the warm and dry winter has led to below normal streamflows. Streamflows over portions of the Middle Mississippi Valley into the Lower Great Lakes region are above normal due to recent rainfall events. 

The combination of the factors described above have resulted in just over half of the CONUS being categorized in some degree of drought by the U.S. Drought Monitor (USDM) as of the time of this assessment. Most of the areas of extreme drought are predominately in the southern U.S., with pockets of extreme drought scattered through the remainder of the U.S. The current USDM can be found at https://droughtmonitor.unl.edu/.

Current Flooding

Minor to moderate river flooding is ongoing and forecast through the remainder of this week across portions of the Ohio River Valley, the Central Gulf Coast, and Michigan. Minor and isolated moderate river flooding is ongoing and forecast over portions of the Pacific Northwest through the next week.

Long Range River Flood Outlook

This outlook is focused on the expectation of flooding with a 50% probability of exceedance, which is considered the most probable level of flooding expected within a season. The 25% probability of exceedance can provide a reasonable worst case forecast for planning purposes, especially in those areas where flooding is primarily driven by convective rainfall. In this assessment, forecast values at the 50% probability will be referred to as “expected” flooding, with forecast values at the 25% probability referred to as “possible” flooding. For areas where there are no significant differences between the 50% and 25% outlook, “expected” will be used to refer to the outlook. To view the latest Long Range River Flood Outlook, including forecasts for specific locations, visit https://water.noaa.gov. 

Northeast

Isolated minor flooding is possible through the remainder of March for portions of New York, Vermont, and southern New England. After mid-March, the existing snowpack will have melted off. This will end the snowmelt related flood risk moving into the spring. Spring flooding in the Northeast is usually driven by a combination of rainfall, snowmelt, and ice jamming on rivers.

Mid-Atlantic

Minor to isolated moderate flooding is possible through the remainder of March as any rainfall may combine with diminishing snowpack that remains across the region, mainly over portions of southern New York and northern New Jersey. By the end of March, little to no snowpack is expected to remain across the Mid-Atlantic region which will reduce the potential for any river flooding caused by spring snowmelt. Dry conditions over the region will help reduce the potential for flooding the remainder of the spring, however, heavy rainfall at any time can lead to flooding.

Southeast

Scattered minor flooding is possible throughout the southeastern U.S. this spring. Nearly the entire Southeast is in some form of drought, and streamflows and soil moisture values are generally reflective of the dry conditions. This will help to mitigate the flood responses from any rainfall events the remainder of the spring. Spring flooding in the southeastern U.S. is driven by heavy rainfall events.

Ohio River Basin

Minor flooding is expected in the Ohio Valley into spring. Moderate flooding is possible across the Ohio Valley through spring, especially in the southern and western portions of the region. Areas that received significant rainfall in early March will remain vulnerable to additional flooding due to saturated soils. Typically, late winter/spring storms are the main drivers of flooding in the area, and spring flooding is normal in the Ohio River Basin.

North Central

Minor to isolated moderate flooding is expected this spring, with a limited possibility for major flooding. This translates to a normal to below normal flood risk for the region. In areas of South Dakota, existing snowpack and moisture frozen in the soil will be the main driver of flood risk. Over the Upper Peninsula of Michigan, a well above average snowpack will increase the flood risk. Elsewhere, where recent precipitation has led to some flooding and those areas will be more prone to flooding later in the season. Overall, the actual flood threat will be determined by weather conditions for the remainder of the spring.

Missouri Basin

Isolated minor to moderate flooding is expected in the Lower Missouri Basin this spring, with moderate to isolated major flooding possible due to forecast and climatologically expected rainfall. Plains snowpack has been largely absent and shallow this winter and is not expected to contribute significantly to spring flooding. Flood risk in the Lower Missouri Basin is primarily driven by thunderstorm activity. Flood risk in the Upper Missouri Basin is driven by snowmelt and rain while in the Mountain West, flood risk is primarily driven by snowmelt.

Arkansas-Red Basin

Isolated minor to moderate flooding is expected in the Arkansas-Red Basin this spring. Flooding in the Arkansas and Red river basins is typically related to spring rainfall events. 

Lower Mississippi Basin

Scattered minor flooding is expected in the Lower Mississippi Valley this spring. For the mainstem of the Lower Ohio and Mississippi rivers, minor flooding is expected this spring with scattered to isolated major flooding possible, primarily near the confluence region of the Ohio and Mississippi Rivers. Overall, flooding in the Lower Mississippi Valley is typically related to spring rainfall events. Flooding in the Lower Ohio and Mississippi rivers is mainly driven by flooding in the Ohio River Basin.

West Gulf

Minor to isolated moderate flooding is expected in portions of eastern Texas this spring. River flooding in this region is typically related to spring rainfall events.

Colorado Basin

At this time, spring snowmelt flooding is not expected in the Colorado River Basin. Generally, mid-March is usually too early to determine spring snowmelt flooding potential with any confidence due to snowmelt across the basin, as snowpacks at higher elevations may continue to build through the spring. However, this year, the well below normal snowpack over the basin will severely limit any snowmelt related flooding.

Northwest

Isolated minor and moderate flooding, primarily due to rainfall, is expected through the end of March. At this time, widespread spring snowmelt flooding is not expected in the Northwest, however, rainfall driven flooding will remain possible through early spring. Generally, mid-March is usually too early to determine spring snowmelt flooding potential with any confidence due to snowmelt across the basin, as snowpacks at higher elevations may continue to build through the spring. West of the crest of the Cascade Mountains, winter is the primary flood season due to the frequency of atmospheric rivers, with spring flooding generally less severe than winter flooding.

California-Nevada

At this time, spring snowmelt flooding is not expected in California or Nevada. Generally, mid-March is usually too early to determine spring snowmelt flooding potential with any confidence due to snowmelt across the basin, as snowpacks at higher elevations may continue to build through the spring. However, this year, the below normal snowpack over the basin will limit any snowmelt related flooding. Winter is the primary flood season in California due to the frequency of atmospheric rivers.

Alaska Spring Ice Breakup Outlook

Overall, the spring breakup and snowmelt flooding potential is above normal across portions of Alaska, particularly across the Interior where breakup flooding occurs most frequently. 

Areas specifically at an elevated flood risk are the Yukon and Tanana river basins due to above normal snowpack, normal to above normal river ice thickness, high freeze-up stages, and rough ice conditions from freeze-up jams. The highest values of above normal snowpack (130 - 150% of normal) is across the Canadian Yukon and eastern Interior Alaska, with additional above normal snowpack across the Yukon-Kuskokwim Delta and parts of the North Slope. Areas with below normal risk of breakup flooding are Southcentral Alaska, the Koyukuk River Basin, and parts of southwestern Alaska as there is a below normal snowpack.

The severity of spring breakup is largely controlled by April and May temperatures. A swift transition from cold early April conditions to warm late April/early May conditions increases the likelihood of a dynamic breakup and raises the risk of ice jam flooding.

Temperatures across much of mainland Alaska are expected to remain well below normal through the remainder of March and potentially into early April. The latest April–June temperature outlook issued March 18 by NOAA’s Climate Prediction Center (CPC) favors above-average temperatures across the western third of mainland Alaska, with below- normal temperatures elsewhere across the Interior. However, CPC notes that confidence in this outlook is lower than normal.

However, CPC notes that confidence in this outlook is lower than normal.

If this general pattern holds, it would decrease the chances of a more dynamic breakup. Near normal temperatures upstream in the headwaters would allow snowmelt to occur more steadily, while warmer conditions downstream would promote earlier snowmelt and ice deterioration before breakup arrives.

Western U.S. Water Supply

Water supply forecasts are produced by the River Forecast Centers in the western U.S. Forecasts are based on current hydrologic conditions including snowpack, soil moisture, and streamflow. As conditions change, particularly over the next few months, forecasts will be updated and available at the Western Water Supply Forecasts webpage.

Spring Flood Outlook and Implications for Gulf of America Hypoxia

In the northern Gulf of America, a large area of low-oxygen forms in the bottom waters during the summer months, often reaching in excess of 5,000 square miles. This area of low-oxygen, otherwise known as the “dead zone”, is strongly influenced by precipitation patterns in the Mississippi-Atchafalaya River Basin (MARB), which drains over 41% of the CONUS. Changes in precipitation influence river discharges into the Gulf, which carry the majority of nutrients fueling the annual dead zone, so examining spring flood risk in the basin can provide a useful indicator of the possible size of the dead zone during the summer.

The predicted spring flood potential across the MARB will likely lead to normal hypoxic conditions in the northern Gulf of America this summer. Most of the MARB is not predicted to experience moderate or major flooding this spring. Absent major flooding, normal springtime discharges of nutrients and freshwater from the Mississippi River are predicted.

In early August, NOAA will measure and report on the size of the hypoxia zone as part of efforts through the Mississippi River/Gulf of America Hypoxia Task Force to evaluate efforts aimed at reducing nutrient loading to the Gulf of America. 

About This Product

The National Hydrologic Assessment (NHA), issued each spring by the National Weather Service (NWS), provides an outlook on U.S. spring flood potential. Analysis of flood risk integrates late summer, fall, and winter precipitation, frost depth, soil saturation levels, streamflow, snowpack, and temperatures. The information presented in this report focuses on spring flood potential, using methods analyzed on the timescale of weeks to months, not days or hours. A network of 13 River Forecast Centers and the National Water Center work collaboratively to assess the risk summarized here at the national scale. The NHA is intended as a national level overview of conditions and not intended to focus on any specific location. Moreover, this assessment displays river and overland flood threat on the scale of weeks or months. Flash flooding or debris flow, which accounts for the majority of flood deaths, is a different phenomenon associated with weather patterns that are only predictable days in advance. To stay current on flood risk in your area, go to water.noaa.gov for the latest local forecasts, warnings, and weather information 24 hours a day.

This site was last updated March 19, 2026 11am CT.