Lewes · Weather, flooding and hazards

Lewes, Delaware: weather, flooding and hazards

Weather, climate, flooding and hazards in Lewes, Sussex County, Delaware: 21 questions answered from NOAA, the state and other official sources.

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Questions about weather, flooding and hazards in Lewes

What is the climate like in Lewes, Delaware?

Using NOAA 1991 to 2020 climate normals from the Lewes station, the nearest of the stations we use, the average January low is 30.2 degrees F and the average July high is 87.7 degrees F. Annual precipitation averages 47.28 inches. The station is not inside Lewes, so readings in town can differ a little, especially near the water. Source: ncei.noaa.gov.

How much snow does Lewes get per year?

The 1991 to 2020 normal for the Lewes station, the nearest station we use, is 10.5 inches of snow a year. Individual winters vary a lot around that average. Source: ncei.noaa.gov.

Is Lewes in a flood zone?

Part of Lewes may sit in a FEMA Special Flood Hazard Area, and the answer depends on the address, so we do not give a town-wide yes or no. The USGS elevation at the town's Census center point is only about 5 feet, which is low ground. Look up a specific property in the FEMA Flood Map Service Center and the DNREC Delaware Flood Planning Tool. Source: msc.fema.gov, floodplanning.dnrec.delaware.gov, epqs.nationalmap.gov.

Is Lewes in a hurricane evacuation zone?

Delaware labels hurricane evacuation zones A, B, C and D, and describes them as low-lying areas susceptible to flooding and storm surge. The state page does not list communities by zone, so we cannot say which zone Lewes or a given address falls in. Use the Know Your Zone lookup tool or interactive map to check an address. Source: preparede.org, dema.delaware.gov.

What body of water is Lewes on?

Lewes sits at the southern edge of Delaware Bay and beside the Lewes & Rehoboth Canal. Cape Henlopen State Park, next to Lewes, has both ocean and bay beaches. Source: visitdelaware.com, ci.lewes.de.us, destateparks.com.

How big is Lewes and how high above sea level is it?

The 2020 Census Gazetteer lists Lewes at 4.192 square miles of land and 0.922 square miles of water. Elevation at the Census center point is about 5 feet above sea level (USGS 3DEP), and ground height varies across town. Source: www2.census.gov, epqs.nationalmap.gov.

Which National Weather Service forecast zone covers Lewes?

The National Weather Service (Mount Holly office) places Lewes in forecast zone DEZ003, Inland Sussex, Delaware. This was read from the NWS point forecast page for the town's Census center point. Source: forecast.weather.gov.

How many days a year reach 90 degrees in Lewes?

NOAA's 1991 to 2020 normals for the Lewes station show an average of 29.2 days a year with a high of 90 degrees F or higher and 0.8 days at 100 degrees F or higher. The station is not inside Lewes, so readings in town can differ a little. Source: ncei.noaa.gov.

When are the last spring freeze and first fall freeze in Lewes?

NOAA's 1991 to 2020 normals for the Lewes station give a 50 percent probability date of March 29 for the last spring freeze (32 degrees F or lower) and November 14 for the first fall freeze. That works out to a growing season of 231 days at the same probability level. The station is not inside Lewes, so readings in town can differ a little. Source: ncei.noaa.gov.

How many freezing nights does Lewes have in a typical year?

NOAA's 1991 to 2020 normals for the Lewes station show an average of 59.2 days a year with a low of 32 degrees F or lower, and 9.9 days with a low of 20 degrees F or lower. The station is not inside Lewes, so readings in town can differ a little. Source: ncei.noaa.gov.

Which month is wettest and which is driest in Lewes?

NOAA's 1991 to 2020 monthly normals for the Lewes station show July as the wettest month at 4.95 inches and February as the driest at 3.17 inches. The station is not inside Lewes, so readings in town can differ a little. Source: ncei.noaa.gov.

How is rainfall split across the seasons in Lewes?

NOAA's 1991 to 2020 normals for the Lewes station list 10.72 inches of precipitation for winter (December to February), 11.04 inches for spring, 13.03 inches for summer and 12.49 inches for fall. Summer is the wettest season. Source: ncei.noaa.gov.

At what tide level does flooding start in Lewes?

The National Weather Service Mount Holly Sussex County tide table, updated May 2016, says flooding begins along Bay Avenue, Cedar Street and Pilottown Road in Lewes at 6.4 feet above MLLW on the Lewes tide gauge. Flooding along Savannah Road (Business US Route 9) near the Lewes and Rehoboth Canal is listed at the same level. Source: weather.gov.

How does the National Weather Service rate coastal flooding near Lewes?

In the National Weather Service Mount Holly Sussex County tide table, updated May 2016, minor tidal flooding begins at 6.0 feet above MLLW on the Lewes gauge and the coastal flood advisory threshold is 6.3 feet. Moderate tidal flooding begins at 7.0 feet and major tidal flooding at 8.0 feet. Source: weather.gov.

What are the highest tides on record at the Lewes gauge that NWS uses for Lewes?

The National Weather Service Mount Holly Sussex County tide table, updated May 2016, lists the highest Lewes gauge readings as 9.3 feet above MLLW on January 23, 2016, 9.2 feet on March 6, 1962, 8.8 feet on January 4, 1992 and 8.7 feet on October 29, 2012 during Post-Tropical Cyclone Sandy. NOAA's own Lewes datum record also lists its observed maximum on January 23, 2016. Source: weather.gov, api.tidesandcurrents.noaa.gov.

How fast is sea level rising near Lewes?

NOAA's relative sea level trend for the Lewes tide gauge is 1.49 inches per decade, with an error of 0.05, based on monthly data from February 1919 to December 2025. The National Weather Service uses Lewes as the reference gauge for Sussex County tides. Source: api.tidesandcurrents.noaa.gov, weather.gov.

Where is the tide gauge that measures Lewes water levels?

The National Weather Service says the Lewes tide gauge is on the bay side of Cape Henlopen in Breakwater Harbor, and that its record begins in January 1919 with gaps from equipment outages. NOAA's sea level trend analysis for station 8557380 starts in February 1919. Source: weather.gov, api.tidesandcurrents.noaa.gov.

In which months are water levels highest at the Lewes gauge?

NOAA's Lewes sea level trend product lists a seasonal cycle in which September is highest at 0.29 inches above the annual average and October next at 0.25 inches. January is lowest at 0.27 inches below the average. Source: api.tidesandcurrents.noaa.gov.

Where do evacuees from Lewes go in a hurricane evacuation?

DelDOT's February 2023 Sussex County evacuation annex says Lewes evacuees head west on US 9 toward Georgetown, then north on SR 1 toward Milford, or west on Route 16 toward Milton and Ellendale. It says at-risk residents should leave at least 24 hours before storm onset and tidal flooding. Source: deldot.gov.

Which past storms brought major tidal flooding to the Delaware coast near Lewes?

The National Weather Service Mount Holly Sussex County tide table, updated May 2016, lists 8.0 feet above MLLW, the major flood level, at the Lewes gauge on September 27, 1985 (Hurricane Gloria), March 3, 1994 and August 27, 2011 (Hurricane Irene). Post-Tropical Cyclone Sandy reached 8.7 feet on October 29, 2012. Source: weather.gov.

When did the current flood maps for the Lewes area take effect?

DNREC's floodplain mapping page says the Kent and Sussex map updates became effective in June 2018. Flood zones depend on the address, so check a specific property in the FEMA Flood Map Service Center or the Delaware Flood Planning Tool. Source: dnrec.delaware.gov.

How these answers are sourced

Every answer on this page cites an official or primary source, such as the town, a state agency, NOAA or the institution itself. Answers SussexCounty.ai could not confirm from a primary source are left out until they can be.