Drought in Delaware

Note:  The next drought report will be on February 4th, 2026

Highlights:

• Precipitation for December was below normal and has been 50 to 75 percent of normal over the last 90 days for most of Delaware.
• The surface water balance was mostly positive, except for the southern half of Sussex County, where precipitation was insufficient to outpace evapotranspiration in December.
• Soil moisture conditions continue to slowly decline statewide, with top level soil moisture in Kent and Sussex Counties being below the 2nd percentile for this time of year.
• Streamflow conditions throughout Delaware are much below normal for this time of year, with some gauges currently below the fifth percentile.
• Groundwater conditions throughout the state are generally below normal for this time of year, with recent trends generally being stable or declining.  

Statewide Drought Discussion

Water conditions throughout Delaware continue to slowly deteriorate, as the state experienced its 5th straight month of below normal precipitation.  Streamflow and groundwater levels are also generally below normal for this time of year.

Precipitation

December 2025 will likely go down as our fifth consecutive below normal precipitation month.  Normal precipitation for December for Delaware is 3.85 inches.  Precipitation data from DEOS Network for December came in with an average of about 2.70 inches statewide.  However, this value is likely low because of an accuracy problem with most DEOS precipitation gauges, which tend to underreport frozen precipitation.  Figure 1 shows that over the last 90 days, most of Delaware has only seen between 50 and 75 percent of normal precipitation.

For the 2025 calendar year, Wilmington finished with just over 40 inches of precipitation (40.52”), which is 4.81 inches below normal.  Meanwhile, Georgetown’s annual precipitation for 2025 dipped below normal in December, finishing the year 0.92 inches below normal (42.96” total).  The year 2025 is the driest year in Delaware since 2017.

Temperature/Evapotranspiration

Water balance conditions were, as anticipated, positive statewide this time of year as precipitation outpaced evapotranspiration.  Reference evapotranspiration was around 1.17 inches on average statewide, with southern Delaware generally seeing higher values than northern Delaware (see Figure 2) due to slightly warmer temperatures in December.  

Surplus water balance conditions are typical for December. There are about three or four months remaining in the dormant season, where precipitation typically outpaces evapotranspiration.  Hopefully things get a little wetter over that timeframe so that we can recharge our hydrologic system more fully before the growing season begins. 

Soil Moisture

With another below normal precipitation month in the books, top level (1 meter deep) soil moisture conditions in Delaware continued to slowly deteriorate.  Northern Kent County now has soil moisture levels at or below the 2nd percentile (going back to 2010), which means two out of Delaware’s three counties now have extremely low soil moisture values for this time of year (Figure 3). 

Streamflow

Throughout December 2025, Delaware’s rivers and streams continued to show below-normal flows for this time of year, which reflects the limited rainfall and lingering dry conditions from earlier in the fall and early winter.

At the USGS streamgage on the White Clay Creek near Newark, discharge measurements recorded in early January 2026 (reflecting late December flows) showed about 35 cubic feet per second (cfs or about 23 mgd) on January 5, 2026, which is significantly below the median flow of about 64 cfs (about 41 mgd) for that date based on historical records. This places streamflow on the White Clay Creek near Newark in the below-normal range compared with typical conditions for early January.

Real-time monitoring shows that streamflows across much of Delaware remain predominantly below normal. In several instances, streamflows dropped into the lower percentiles (some less than 5th percentile) compared with long-term records for December. Low streamflows will have an affect on water availability, ecosystem health, and water quality across Delaware if conditions persist into winter and early spring.

Chlorides

Recent precipitation has diluted chloride levels in the Christina River near Newport to 129 ppm after reaching a high of 1165 ppm at the end of October. This decrease is largely due to increased river flows in recent days, which have allowed fresh water to dilute the tidal saltwater, pushing the chlorides further downstream toward the mouth of the Christiana River. Without rainfall to continue dilution, chloride concentrations may again increase to concentrations seen at the end of October.  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.

On the Delaware River, the typical November median salt front position is around River Mile 70 (near the  mouth of the Christina River), meaning the current location (approximately River Mile 85) is noticeably farther upstream than average for this time of year (the average location of the salt front during December is River Mile 69). Continued monitoring through the winter will help assess whether upcoming rainfall and river discharge push the salt front back downstream toward its usual seasonal position.

Groundwater

During early December 2025, groundwater levels in Delaware continued to reflect the effects of an extended period of below-normal rainfall and low streamflows that began in fall 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 (USGS well Db24-18) had measured water levels around 15.4 feet below land surface, which is just below the normal range for early December (typical range ~12.5–15.0 feet). This indicates that groundwater in the unconfined shallow aquifer remained lower than expected for the month of December.

Well Hb12-05, which had been at the low end of normal since early fall, fell into the below-normal range in early December but recharged a bit and reached the normal range by the end of December. However, the water level has since fallen back into the below normal category.

A monitoring well in southwestern Kent (Mc51-01a) continued to track below the 5th percentile at around 17.6 feet below land surface, a level that may represent a new record low for that well if confirmed with longer records.

At least one well (Pf24-02) remained within the normal range (albeit the low end of normal), 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.

Compared with notable drought periods such as the mid-1960s, the 1980s, and the late 1990s–early 2000s (when extended dry spells led to widespread water shortages and some wells were dramatically drawn down), the early December 2025 groundwater levels show similarities in trend but not yet as extreme statewide consequences.

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

Despite a little thawing out this week, the outlook for January is expected to keep the winter chill in place.  Figure 5 shows the temperature outlook for January 2026 from the NOAA Climate Prediction Center (CPC).  This is consistent with the longwave upper atmospheric trough that’s been in place over the Eastern United States since late November.  Until this pattern breaks down, we should continue to expect cooler than normal temperatures.  

But perhaps more importantly for this time of year, the precipitation pattern in January is equal chances of being above normal or below normal (Figure 6).

This means the CPC did not have enough information or decisive data to predict above or below normal precipitation.  While this could mean we see something close to normal precipitation in January, that doesn’t mean we will.  More than likely, until the current weather pattern changes, we’ll probably continue seeing drier than normal conditions.  La Nina is expected to wane later this winter, so maybe that helps shift our weather pattern into a wetter regime.  Until then, let’s hope January doesn’t end up as the sixth straight month with below normal precipitation.