23 May 2021
Read MoreNew Climate Normals :
A Comparison of the 1991 – 2020 Climatological Normals
with the 1981 – 2010 Climatological Normals ,
focusing on Columbia, SC and Augusta, GA.
Daniel C. Miller
National Weather Service
Columbia, SC
Introduction
o What are Climate Normals ?
o Normal daily/monthly/annual highs, lows, average temps, precipitation
amounts, etc
Introduction
Climate Normal Examples
Introduction
o How are these climate normals calculated?
o Using observations taken over a 30 -year period
o WMO established the 30 -year time period standard for normals
o Early in the 20 th century when most locations around the world only had
about 30 years worth of continuous weather observations
o Updated every 10 years
Background
o NCEI recently released 1991 -2020 climatological
normals for the US
o Normal daily/monthly/annual temperatures,
precipitation amounts
o Replacing the 1981 -2010 dataset
What are climate normals used for?
o Forecasting
o Climate comparison by location
o Can identify trends in time
o Industry/Personal uses
Outline
o CONUS Comparison
o Change in average annual temperature and precipitation amount
o Normals comparison for Columbia, SC and Augusta, GA
o Monthly/Annual Average Temperature and Precipitation Amount
o Other Climate Statistics
o New Tropical Cyclone Normals for the Atlantic Basin
What has changed with the new normals ?
o US Annual Average Temperature:
o Warmer for most of the CONUS
o Cooler Northern Plains/Upper Midwest
o US Annual Average Precipitation Amount:
o Wetter values for much for the north and east
o Drier Central/Southern Plains, Rockies, Desert SW
o For both Columbia, SC and Augusta, GA:
o Warmer and wetter values for annual average temperature and precipitation
amount.
o Slight increase in number of named Tropical Cyclones and Hurricanes in the
Atlantic Basin
o No change in number of “major” hurricanes (Cat. 3 or higher on Saffir -Simpson scale)
Month 1981 -2010 Normal 1991 -2020 Normal Difference
January 44.8 45.7 + 0.9
February 48.5 49.1 + 0.6
March 55.6 55.9 + 0.3
April 63.4 64.1 + 0.7
May 71.7 72.2 + 0.5
June 79.1 79.1 0
July 82.2 82.4 + 0.2
August 80.8 81.0 + 0.2
September 74.7 75.5 + 0.8
October 64.1 64.6 + 0.5
November 54.8 54.0 -0.8
December 46.7 47.7 + 1.0
Annual 63.9 64.3 + 0.4
Columbia SC
Monthly/Annual Normal Average Temperature Comparison ( ?F)
Month 1981 -2010 Normal 1991 -2020 Normal Difference
January 45.4 47.4 + 2.0
February 49.1 50.8 + 1.7
March 55.9 57.5 + 1.6
April 62.7 64.6 + 1.9
May 71.1 72.7 + 1.6
June 78.6 79.7 + 0.9
July 81.6 82.8 + 1.2
August 80.5 81.8 + 1.3
September 74.6 76.4 + 1.8
October 64.4 66.0 + 1.6
November 55.2 55.6 + 0.3
December 47.2 49.4 + 1.8
Annual 63.9 65.4 + 1.5
Augusta GA
Monthly/Annual Normal Average Temperature Comparison ( ?F)
Month 1981 -2010 Normal 1991 -2020 Normal Difference
January 3.58″ 3.49″ -0.09″
February 3.61″ 3.39″ -0.22″
March 3.73″ 3.57″ -0.16″
April 2.62″ 2.83″ + 0.21″
May 2.97″ 3.49″ + 0.52″
June 4.69″ 4.97″ + 0.28″
July 5.46″ 5.35″ -0.11″
August 5.26″ 4.65″ -0.61″
September 3.54″ 3.91″ + 0.37
October 3.17″ 3.13″ -0.04″
November 2.74″ 2.76″ + 0.02″
December 3.22″ 3.70″ + 0.48″
Annual 44.59″ 45.24″ + 0.65″
Columbia SC
Monthly/Annual Normal Precipitation Amount Comparison
(Inches)
Month 1981 -2010 Normal 1991 -2020 Normal Difference
January 3.91″ 3.84″ -0.07″
February 3.92″ 3.67″ -0.25″
March 4.18″ 4.08″ -0.10″
April 2.84″ 2.92″ + 0.08″
May 2.65″ 3.05″ + 0.40″
June 4.72″ 4.75″ + 0.03″
July 4.33″ 4.48″ + 0.15″
August 4.32″ 4.61″ + 0.29″
September 3.22″ 3.60″ + 0.38
October 3.27″ 2.56″ -0.71″
November 2.82″ 2.66″ -0.16″
December 3.39″ 3.87″ + 0.48″
Annual 43.57″ 44.09″ + 0.52″
Augusta GA
Monthly/Annual Normal Precipitation Amount Comparison
(Inches)
Location 1981 -2010 Normal 1991 -2020 Normal Difference
Columbia, SC 71.6 80.9 + 9.3
Augusta, GA 82.0 86.3 + 4.3
Annual Number of Days > 90F Comparison
Annual Number of Days < 32F Comparison
Location 1981 -2010 Normal 1991 -2020 Normal Difference
Columbia, SC 47.3 46.5 -0.8
Augusta, GA 51.3 51.0 -0.3
Annual Number of Days > 100F Comparison
Location 1981 -2010 Normal 1991 -2020 Normal Difference
Columbia, SC 5.2 6.0 + 0.8
Augusta, GA 5.5 5.9 + 0.4
Location 1981 -2010 Normal 1991 -2020 Normal Difference
Columbia, SC November 3 rd November 7 th 4 days later
Augusta, GA November 5 th November 9 th 4 days later
Average Date of the First Fall Freeze Comparison
Average Date of the Last Spring Freeze Comparison
Location 1981 -2010 Normal 1991 -2020 Normal Difference
Columbia, SC March 30 th March 25 th 5 days earlier
Augusta, GA March 29 th March 23 rd 6 days earlier
Location 1981 -2010 Normal 1991 -2020 Normal Difference
Columbia, SC 1.5″ 1.2″ -0.3″
Augusta, GA 0.9″ 0.8″ -0.1″
Annual Snowfall Amount Comparison
New Tropical Cyclone Normals for the Atlantic Basin
Summary
o US Annual Average Temperature:
o Warmer for most of the CONUS
o Cooler Northern Plains/Upper Midwest
o US Annual Average Precipitation Amount:
o Wetter values for much for the north and east
o Drier Central/Southern Plains, Rockies, Desert SW
o For both Columbia, SC and Augusta, GA:
o Warmer and wetter values for annual average temperature and precipitation
amount.
o Slight increase in number of named Tropical Cyclones and Hurricanes in the
Atlantic Basin
o No change in number of “major” hurricanes (Cat. 3 or higher on Saffir -Simpson scale)
Note
o Record values still use the entire period of record
o Continuous temperature and precipitation records for Columbia, SC and
Augusta, GA date back to the late 1800’s.
New Climate Normals :
A Comparison of the 1991 – 2020 Climatological Normals
with the 1981 – 2010 Climatological Normals ,
focusing on Columbia, SC and Augusta, GA.
Daniel C. Miller
daniel.miller@noaa.gov
National Weather Service
Columbia, SC
Thank You!