Drought in Delaware

Note:  The next drought report will be on May 20th, 2026

Highlights:

• Precipitation continues to lag statewide, putting us way behind since the fall of last year.
• Temperatures have started out on the warmer side for the early part of the growing season, thus increasing evapotranspiration and the net loss of water from the environment.
• Streamflows are down statewide, with some locations experiencing their lowest levels ever for this time of year.
• Groundwater continues to struggle to recover from consecutive winters with lackluster precipitation.
• The seasonal outlook for May through July shows that drought conditions are likely persist over the next few months, though mostly likely around the level they are currently.

Statewide Drought Discussion

Eight consecutive months of below normal precipitation (a deficit of 11.48 inches going back to August of last year) has led to historically low flows on some streams and creeks and continued below normal groundwater conditions for most of the state.  

Precipitation

March 2026 became the eighth straight month with below statewide normal precipitation (relative to 1991-2020 base period).  April precipitation has fared no better.  Month-to-date, statewide precipitation for the DEOS Network has averaged 1.46 inches through the 21st.  We typically see about 3.5 inches in April, so we have a lot of catching up to do in the final week of the month to break our dry month streak.  Spatially, precipitation has been fairly evenly distributed across the state (see Figure 1), with the lowest totals occurring in Adamsville (0.86 inches) and Townsend (1.04 inches), and the highest totals in the state occurring at Stockley (2.55 inches) and Newark (2.42 inches).

Temperature/Evapotranspiration

Despite the freezing conditions we experienced on a couple of mornings earlier this week, temperatures for the last month or so have been fairly mild.  With above normal temperatures, evapotranspiration tends to be higher, and this is the case for this month as well.   Figure 2 shows that evapotranspiration has been normal to high for most of the state, while several watersheds are in the Very High category.  

Soil Moisture

Early growing season soil moisture is heavily driven by recent precipitation and the water holding capacity of the soil.  At this time, most natural vegetation has experienced leaf emergence, which means most plants are actively growing and using soil moisture.  Without rainfall, the soil moisture reserves we have can quickly dissipate and leave early season plants and especially crops very vulnerable to drought.  Figure 3 shows estimated soil moisture in the top 1 meter of soil from NASA satellite imagery.

Delaware, along with most of the Mid-Atlantic region of the United States, is experiencing fairly low soil moisture values for this time of year.  Soil moisture should be on the relatively high side this time of year  (55 – 70% typically), however our soil moisture is currently in the 35-45% range statewide.  That puts soil moisture for most of the state below the 5th percentile for this time of year.  If weather conditions stay like they are, we could be approaching the lowest early season soil moisture values we’ve seen since 2010, which is when this soil moisture product’s records began.

Streamflow

Despite the freshwater inflow resulting from the melting of winter ice and snowpack, fluvial discharge rates across northern Delaware have largely regressed to pre-freeze baseline levels. With the exception of the Brandywine Creek, which exhibits a marginal upward trend in volume, current hydrologic data indicates a significant departure from seasonal norms. The flows on the White Clay Creek at Newark, White Clay Creek near Newark, Red Clay Creek near Stanton, and the Brandywine Creek at Wilmington are in the 5th to 10th percentile range (much below normal). To be considered in the normal range, streamflows need to be between the 25th and 75th percentiles. This is the time of year when flows should be solidly in the normal range.

Having increased slightly, real-time monitoring in Kent and Sussex Counties shows that streamflows across these counties remain predominantly below normal. Flows on the St. Jones River at Dover remain in the 10th to 25th percentile (below normal) and flows on the Nanticoke River at Bridgeville are in the 5th to 10th percentile (much below normal).

These sustained low-flow conditions pose significant risks to aquifer recharge and water quality parameters. To transition these systems back to seasonal normals, the state requires a sustained period of statistically significant, above-normal precipitation over the next 60 days to offset current deficits.

Chlorides

Chloride concentrations have decreased from the winter high of 165 ppm (due to road salt) to a very low level of 46.2 ppm. Elevated chloride levels can speed up the corrosion of pipes, bridges, and other infrastructure, leading to higher maintenance costs and a greater risk of damage. They also pose a threat to aquatic ecosystems, as fish, insects, and plants in freshwater streams are especially sensitive to changes in salinity.

Groundwater

During February and into early March, groundwater levels in Delaware continued to reflect the effects of an extended period of below-normal precipitation and low streamflows that began in the fall of 2025. Recent monitoring shows that several wells across the state were at or below normal ranges for this time of year, with some wells exhibiting historically low levels.

A shallow monitoring well just south of Newark (DGS well Db24-18) had near real-time water levels around 14.51 feet below land surface, which is below the normal range for April (typical range ~8.0 to 12.7 feet below land surface). This indicates that groundwater in the unconfined shallow aquifer remained below normal for this time of year, which is when recharge should be occurring.

Well Hb12-05, (located in southern New Castle County) has decreased to the low end of normal once again after being firmly in the normal range in early January.

A monitoring well in southwestern Kent (Mc51-01a; Figure 4) has continued to track below the 5th percentile at around 15.0 feet below land surface. Since last fall, groundwater levels may represent a new record low for that well if confirmed with longer records.

At least one well (Pf24-02 located south of Georgetown) remained within the normal range, reflecting geographic variability in groundwater response across Delaware.

Delaware’s groundwater system responds slowly to changes in precipitation compared with surface waters (like streams and rivers). As a result, patterns of dry weather tend to show up first in streamflow and soil moisture, and then, if dry conditions persist, in groundwater levels and aquifer conditions.

Groundwater is a major source of drinking water and irrigation supply in much of Delaware, especially south of the Chesapeake and Delaware Canal. Extended periods of low levels can reduce well yields and may require deeper pumping or alternative supply strategies in some communities. Persistently low groundwater levels increase the risk of saltwater intrusion in coastal and near-estuarine aquifers, complicating long-term freshwater sustainment. In addition, low groundwater can stress wetlands and baseflow conditions to streams during dry periods, affecting fish, invertebrates, and riparian habitats.

Because groundwater responds more slowly than surface water, continued monitoring into winter and early spring 2026 will be critical to assess whether recent rainfall and seasonal recharge allow levels to rebound or if dry conditions continue to depress the water table.

Weather and Climate Outlook

Figures 5 and 6 show predicted probabilities of temperature and precipitation, respectively, for the United States from May through July.  

As can be seen in these figures, NOAA’s Climate Prediction Center is calling for warmer than normal conditions for nearly the entire country, while wetter than normal conditions are predicted along the eastern seaboard and the southwest United States.  While slightly wetter conditions would certainly be welcome, the likely above normal temperatures will make it difficult to see much in the way of recovery from the drought conditions we’re currently experiencing, especially in our groundwater and surface water systems which need a surplus in the water budget over an extended period of time to see significant improvement.

One final note is that the CPC’s and other seasonal forecasts from across the world are calling for a strong to very strong El Nino to develop later this year.  The effects of this shift in the climate system will likely have a limited impact on our region throughout the summer, as our climate tends to be dominated by other factors during that time of the year.  However, this could have significant implications for our winter conditions, when El Nino becomes more important.  El Nino patterns tend to keep our weather milder and wetter.  Given that we’ve experienced two consecutive winters with lackluster precipitation, this shift could be quite helpful to our long-term water needs, if the anticipated El Nino pattern persists into the winter of 2026-2027.  That said, we still have a growing season to get through before we can worry too much about that.