Key facts: New Castle
- The city's four earthen dikes date to the late 1600s, and their tops, at about 8.5 feet, sit below the 100-year flood elevation.[1]
- The Dutch West India Company laid out the grid and green in 1651.[2]
- New Castle can flood from upstream river flows, from a tidal surge, or from both at once, and much of the city lies in the coastal floodplain, according to DNREC.[1]
Dikes from the 1600s
The city's four earthen dikes date to the late 1600s, and their tops, at about 8.5 feet, sit below the 100-year flood elevation.[1] That is a sobering number for anyone in the old town. It makes a separate flood policy and a practiced move-to-higher-ground plan worth having.
A closer look in New Castle
Working on a 1651 street plan
Flood claims recorded in New Castle County
New Castle sits in New Castle County. FEMA publishes every National Flood Insurance Program claim with personal details removed, which gives a plain record of where water has reached insured buildings here.
| Measure | Count |
|---|---|
| Flood insurance claims on record | 1,575 |
| Year with the most claims | 2003 (263) |
| Largest named event | Hurricane Floyd (210) |
| Claims outside high-risk A and V zones | 32% |
| Claims on buildings built before 1975 | 80% |
County-wide counts of insured claims only. Uninsured losses, burst pipes and appliance leaks are not in this data.
What the New Castle claim record shows
For New Castle homes, the local precedents are the events behind the most New Castle County claims: Hurricane Floyd (210 claims), Hurricane Irene (144 claims) and Hurricane Ida (90 claims).
About 32% of claims with a recorded zone came from outside the high-risk A and V zones, so a moderate-risk label does not mean a New Castle home stays dry.
If your New Castle home is older, note that buildings from before 1975 make up 80% of county claims with a known build date. Many predate current flood maps, so inspect low outlets, ductwork and subfloors closely after any water event.
Federal disaster history for New Castle County
FEMA lists 17 federal declarations covering New Castle County. The most common types are hurricane (9), snowstorm (4) and biological (2). The latest are Remnants of Hurricane Ida in 2021, Tropical Storm Isaias in 2020 and Covid-19 Pandemic in 2020. Federal aid can open after a declaration, so New Castle owners should look it up before discarding damaged items.
New Castle weather and your home
Weather records for New Castle from 2015 through 2024 average 52 inches of precipitation a year, and August and July are the wettest months. The area averages 11.0 days a year with an inch or more.
New Castle falls to 20°F or below on about 13 nights a year, which puts pipes in exterior walls, crawl spaces and garages at risk.
When rain falls in New Castle
Seasonal averages for New Castle, 2015 through 2024. Plan roof, gutter and sump pump checks before the wettest stretch.
| Season | Average | Share of year |
|---|---|---|
| January to March | 11.6 in | 22% |
| April to June | 13.5 in | 26% |
| July to September | 15.2 in | 29% |
| October to December | 11.4 in | 22% |
Modeled from Open-Meteo historical weather data. Precipitation includes rain and melted snow.
New Castle home checklist from these records
- Don't rely on recent quiet years. Only 15% of New Castle County claims date from 2015 or later, so older floods still show what can happen.
- Insulate exposed pipes before 13-plus hard-freeze nights arrive, and know your main shutoff.
- Test any sump pump before August, since New Castle averages 11 days a year with an inch or more.
- Keep dated photos of each room. After Hurricane Floyd, 210 insured New Castle County owners filed claims at about the same time.
What to tell the New Castle contractor
- Whether you are in the historic district or a suburb with a New Castle address
- Whether tidal or rain water entered
- What original materials got wet
Services New Castle callers ask about
Questions
New Castle water damage questions
Why is New Castle so flood-prone?
Low ground beside a tidal river, with old dikes below the 100-year flood level, leaves little margin.[1]
Can old plaster survive a flood?
Sometimes, though contaminated flood water usually means more removal. Test before disturbing older finishes.