Underlying Science
Intensifying Rainfall and Flooding in New Jersey
- Higher temperatures increase the energy in storms and allow the atmosphere to hold more water, which increases the potential for more intense precipitation and flooding
- By the end of the 21st century, heavy storm events are projected to occur 200 to 500% more often and with more intensity than in the 20th century
- Major flood events hit New Jersey in 2000, 2004, 2005, 2006, 2007, 2010, 2011, 2012, 2016, and 2021
- NJDEP and the Northeast Regional Climate Center, a National Oceanic and Atmospheric Administration (NOAA) partner, released two New Jersey-specific studies in November 2021:
- Confirming increases in precipitation across New Jersey over the last 20 years
- Projecting further increases in precipitation intensity over the coming decades
- The data presently used to analyze flood potential in waterways and in the design of stormwater infrastructure is outdated—it includes data only through 1999
- The precipitation expectations that presently guide state policy, planning and development criteria, and which rely upon data obtained through 1999, do not accurately reflect current precipitation intensity conditions
Highest Observed and Projected Precipitation Change
Observed Precipitation Change Since 1999
Projected Precipitation Change Under a Moderate Emissions Scenario for 2050-2099
Highest % Change
Highest observed and projected extreme precipitation percent changes in New Jersey. For a 24-hour storm, the highest percent change of the analyzed NJ stations from 1950-1999 to 1950-2019 is displayed in blue bars for recurrence intervals (2-year, 10-year, 100-year). The green bars display the highest NJ county projected percent change at the upper likelihood for each recurrence interval under a moderate emissions scenario from 1950-1999 to 2050-2099.