Summer 2023 Climate Outlook for northeastern SC and southeastern NC

Summer 2023 is shaping up to be a warm one according to outlooks issued by the Climate Prediction Center.  Across the eastern Carolinas there is a 50 to 60 percent chance for temperatures to run above normal this summer.  There's not as much certainty with precipitation, but forecasters believe much of the eastern U.S. will see a slightly elevated potential for above normal rainfall this summer.

Developing El Niño and Temperatures

After almost three years of persistent La Niña conditions, ocean water temperatures across the tropical east Pacific Ocean are warming above normal and will likely cause El Niño to develop for the first time since 2019.  El Niño is the warm phase of ENSO -- the El Niño Southern Oscillation.  ENSO brings various weather and climate impacts around the world varying by location and by season. 

For the Carolinas during summer, El Niño's impact on temperatures is small.  Statistical analysis since 1950 shows El Niño is associated with a slight tendency for cooler summer temperatures here, but there is considerable overlap between years which makes it a rather poor predictor by itself.

Learn more about ENSO, El Niño, and La Niña...

The Climate Prediction Center's outlook for this summer is for a 50 to 60 percent chance for above normal temperatures.  There are two main factors behind this outlook: computer models and climate change.  Carbon dioxide and methane continue to increase in concentration in the atmosphere. These gases, released into the air from the burning of fossil fuels and from natural gas extraction, trap more and more of the sun's heat which leads to a warming climate. The past several summers have had observed temperatures near or above the 1991-2020 average, and this summer may turn out no different.

On average, 90 degree high temperatures are recorded 20 times a year in Myrtle Beach, SC; 45 times a year in Wilmington, NC; and 70 times a year in Florence, SC.  Extremely hot temperatures of 100 degrees average three occurrences a year in Florence, and only once a year in Wilmington.  Both Florence and Lumberton, NC saw 100 degree temperatures last summer, but it's been 18 years since the normally cool seabreezes in Myrtle Beach have allowed temperatures to reach 100 there. (July 27, 2005)

Cooling degree days are a way to relate seasonal temperatures to energy consumed by air conditioning a home or business.  Each degree that a day's average temperature runs above 65° F accumulates one cooling degree day, and summing up these cooling degree days across a season shows how much energy is needed for air conditioning. 

For the climate across the eastern Carolinas, each 1° F that summer temperatures run above normal causes number of cooling degree days to rise by approximately 6 percent.  Energy bills will likely be higher than normal this summer due to increased cooling costs -- dependent on exactly how far seasonal temperatures stray from normal.

More info on Cooling and Heating Degree Days from the EPA...

Precipitation

Areas of moderate drought at the end of the winter have vanished thanks to plentiful rainfall across most portions of the eastern Carolinas this spring.  Rainfall amounts over the past three months have been near to above normal with the exception of locally dry conditions across Williamsburg and Florence counties in South Carolina.

There is very little historic difference between rainfall in El Niño, neutral, and La Niña summers across the eastern Carolinas. A small tendency is noted for El Niño summers to run drier than others, but there is considerable overlap between years and this by itself is not a reliable predictor.

The Climate Prediction Center outlook for the Carolinas this summer is for a slightly enhanced potential for above normal precipitation.  This is mainly based on recent observed trends toward higher summer rainfall totals.  Extended range model blends including the NMME (North American Multi-Model Ensemble) and C3S (European Copernicus) suggest near normal to slightly above normal rainfall totals as well.

Two positive aspects to an outlook for adequate rainfall during the summer are:

• The Climate Prediction Center's Drought Outlook through the end of August shows no significant drought is likely to develop across the Carolinas.
• The National Interagency Fire Center (NIFC) shows a near normal risk of wildfire through August across the Carolinas.

Hurricane Season

NOAA's official outlook has an increased likelihood of a near-normal hurricane season across the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico with the number of tropical storms, hurricanes, and major hurricanes near the center of their historic ranges. 

Why are the forecast ranges so wide?  NOAA forecasters carefully craft their forecasts so that there is at least a 70 percent chance that the actual number of tropical storms, hurricanes, and major hurricanes will fall into those forecast ranges at the end of the season.  If only a single forecast value was provided, the chance of that forecast verifying would be very small.

There are multiple competing factors in the ocean and atmosphere that make this season's hurricane outlook particularly challenging.

1. El Niño is developing across the tropical east Pacific Ocean.  This climate oscillation typically reduces the number and strength of Atlantic hurricanes by increasing wind shear across the Atlantic Ocean. 
2. Ocean surface temperatures across the Main Development Region in the tropical Atlantic Ocean are currently above normal and are forecast to remain above normal during the heart of the hurricane season.  Oceanic heat is the fuel that hurricanes live on, and by itself can lead to more and stronger hurricanes.
3. Monsoon-related rainfall across Africa's Sahel region is expected to be above normal this summer.  This area is where tropical waves (also called easterly waves) form, some of which become our long tracked Atlantic hurricanes.  By itself more rainfall here yields more tropical waves, some of which could become tropical storms and hurricanes.

The official Atlantic Hurricane Season begins June 1 and lasts through November 30.  The bulk of our significant local hurricane impacts have occurred in September or early October, however destructive storms can still affect the Carolinas during summer.  Some of our more notable July and August hurricane strikes include:

• Hurricane Isaias (August 2020)
• Hurricane Irene (August 2011)
• Hurricane Charley (August 2004)
• Hurricane Bonnie (August 1998)
• Hurricane Bertha (July 1996)

The list of names for this year's tropical storms and hurricanes are:

In the unlikely event all of the names on this list are used, there is a backup list of names ready.

Coastal and River Flooding

The risk of coastal flooding will be highest this summer during full moons on July 3, August 1, and August 30.  These are times when astronomical tides will be large enough that only a modest period of onshore winds or a nearby storm system could easily produce coastal flooding.  Tides associated with this summer's new moons on June 18, July 17, and August 16 will be smaller and should pose a lesser risk for flooding.

Official astronomical tide forecasts are available for Wrightsville Beach and Myrtle Beach.  We also produce a local 3-day Total Water Forecast which takes winds and storm surge into account for Wrightsville Beach and Myrtle Beach.

Probabilistic river stage forecasts produced by the Southeast River Forecast Center suggest a near normal potential for river flooding across the region this summer including the Carolinas.  River levels going into summer are generally near to slightly below normal.  Evaporation and water usage by trees and plants are both highest during the summer months, so it generally takes well above normal rainfall to lead to river flooding concerns.

Long range probabilistic river outlooks are issued once a month for points along many of the larger rivers across the eastern Carolinas.  Check our Advanced Hydrological Prediction Service (AHPS) page for these and for additional forecasts and outlooks.

Other Links of Interest

• Climate Prediction Center Seasonal Temperature and Precipitation Outlooks
• Climate Prediction Center Seasonal Hurricane Outlook for 2023
• Average Temperatures and Precipitation for Wilmington, NC | Florence, SC | Myrtle Beach, SC | Lumberton, NC
• NWS Wilmington, NC North and South Carolina Historic Heatwaves

Research and Page Author: Tim Armstrong
Last Updated: May 31, 2023