Millsboro · Weather, flooding and hazards

Millsboro, Delaware: weather, flooding and hazards

Weather, climate, flooding and hazards in Millsboro, Sussex County, Delaware: 18 questions answered from NOAA, the state and other official sources.

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Questions about weather, flooding and hazards in Millsboro

What is the climate like in Millsboro, Delaware?

Using NOAA 1991 to 2020 climate normals from the Georgetown Delaware Coastal Airport station, the nearest of the stations we use, the average January low is 28.6 degrees F and the average July high is 87.7 degrees F. Annual precipitation averages 43.88 inches. The station is not inside Millsboro, so readings in town can differ a little, especially near the water. Source: ncei.noaa.gov.

How much snow does Millsboro get per year?

The Georgetown airport normals table we use for Millsboro does not publish snowfall. The nearest station we fetched with a 1991 to 2020 snowfall normal is the Lewes station, at 10.5 inches a year. Treat that as a regional reference, not a measurement for Millsboro. Source: ncei.noaa.gov.

Is Millsboro in a flood zone?

Part of Millsboro 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 about 29 feet. 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 Millsboro 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 Millsboro 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 Millsboro on?

Millsboro sits at the headwaters of the Indian River. The Delaware Public Archives says the river was dammed there around 1792 at a place called Rock Hole for a grist mill and sawmill. Source: archives.delaware.gov.

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

The 2020 Census Gazetteer lists Millsboro at 5.11 square miles of land and 0.235 square miles of water. Elevation at the Census center point is about 29 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 Millsboro?

The National Weather Service (Mount Holly office) places Millsboro 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 Millsboro?

NOAA's 1991 to 2020 normals for the Georgetown airport station show an average of 30.5 days a year with a high of 90 degrees F or higher, 0.5 days at 100 degrees F or higher and 110.8 days at 80 degrees F or higher. The Georgetown airport station is not inside Millsboro, so readings in town can differ a little. Source: ncei.noaa.gov.

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

NOAA's 1991 to 2020 normals for the Georgetown airport station give a 50 percent probability date of April 4 for the last spring freeze (32 degrees F or lower) and November 6 for the first fall freeze. That works out to a growing season of 217 days at the same probability level. The Georgetown airport station is not inside Millsboro, so readings in town can differ a little. Source: ncei.noaa.gov.

How much heating and cooling demand does Millsboro have in a year?

NOAA's 1991 to 2020 normals for the Georgetown airport station list 4070.2 heating degree days and 1396.1 cooling degree days a year, which are NOAA's measures of heating and cooling demand. The Georgetown airport station is not inside Millsboro, so readings in town can differ a little. Source: ncei.noaa.gov.

Which month is wettest and which is driest in Millsboro?

NOAA's 1991 to 2020 monthly normals for the Georgetown airport station show September as the wettest month at 4.54 inches and February as the driest at 2.58 inches. The Georgetown airport station is not inside Millsboro, so readings in town can differ a little. Source: ncei.noaa.gov.

How often does Millsboro get an inch or more of precipitation in one day?

NOAA's 1991 to 2020 normals for the Georgetown airport station show an average of 11.1 days a year with 1.00 inch or more of precipitation and 2.2 days with 2.00 inches or more. The Georgetown airport station is not inside Millsboro, so readings in town can differ a little. Source: ncei.noaa.gov.

Are Delaware's record high and low temperatures from Millsboro?

Yes, according to the Delaware Climate Office, which cites NOAA. It lists the state's highest temperature as 110 degrees F at Millsboro on July 21, 1930 and the lowest as minus 17 degrees F, also at Millsboro, on January 17, 1893. Source: climate.udel.edu.

At what tide level does flooding start in Millsboro?

The National Weather Service Mount Holly Sussex County tide table, updated May 2016, says flooding begins in Millsboro at 6.8 feet above MLLW on the Lewes tide gauge. The table does not name specific Millsboro roads. Source: weather.gov.

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

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 Millsboro?

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.

What does Sussex County's hazard plan rank as the biggest weather risks for Millsboro?

Sussex County's December 2022 hazard mitigation plan ranks flooding (riverine and coastal) first, hurricanes and tropical storms second, severe thunderstorms third, drought fourth and extreme heat and cold fifth. Millsboro is one of the plan's participating jurisdictions, with its own annex. Source: bridgeville.delaware.gov.

Is Millsboro part of a StormReady community?

The National Weather Service StormReady page for Delaware lists Sussex County as StormReady, along with Kent and New Castle counties. It does not list Millsboro separately. Source: weather.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.