SIOUX CITY AREA
By Richard Ryrholm
Climatic Focal Point
National Weather Service, Sioux Falls
...ANOTHER WET YEAR IN SIOUXLAND...WITH ROLLER COASTER TEMPERATURES...
Temperatures averaged somewhat below normal in 2009, or 0.6 degree below the normal of 48.3 degrees. However, it was quite a roller coaster from month to month compared to normal. It was yet another wet year in Siouxland in 2009, totaling 32.82 inches precipitation at the Sioux Gateway Airport, or 6.83 inches above normal. Out of the past 19 years, only 5 years (or 26%) had below normal precipitation, and the 19 year average of 28.35 inches was about 2.4 inches above the official 30 year normal of 25.99 inches. Snowfall for the 2008-09 season was 35.5 inches, or 4.1 inches above normal. However, 22.6 inches or 64% of the 2008-09 seasonal snow total occurred in December 2008, which seems to be repeating itself through December 2009 with an all-time monthly record snowfall of 34.0 inches. The following is a chronological account of the weather events of 2009 in Siouxland...
January 12th … Strong northwest winds gusting up to 52 mph in the afternoon combined with 1 to 3 inches snowfall and existing snow cover to produce blizzard conditions in the area into the evening. Temperatures dropped from a high of 35 before noon, to 2 below zero and wind chills around 20 below by late evening.
January 14-15th … Bitter cold arctic air plunged into the area with wind chills dropping to the 20s then 30s below zero, down to near 40 below zero at 7 AM on January 15th. The 15th was the coldest day of the winter and the year with a record low of 20 below and a record low daily maximum of 2 below zero. This was the coldest high temperature in Sioux City in the last 10 years, since the 4 below zero high on January 4th 1999. There were 11 days with lows of zero or below in January 2009.
February 9th … An intense low pressure system brought very strong southwest winds gusting up to 53 mph in the evening, for the strongest recorded wind speed of 2009.
February 26-28th … Some freezing rain and sleet the morning of the 26th, changed to periods of light snow, accumulating 2.5 inches until early on the 28th.
March 22-23rd … Official spring started with 1.24 inches of rainfall, and some severe weather west to south of Sioux City in the late afternoon of the 23rd.
March thru May … The meteorological springtime period of March thru May was on the dry side overall with less than half the normal precipitation. There was only 2.5 inches snowfall from March through April. On April 4-5th the Siouxland was missed by a snowstorm that went north, west, and south of the area. There were 5 days of 90 degree temperatures from late April through May. The first day was a record high of 92 on April 23rd. A high of 97 occurred on May 19th for the warmest temperature of 2009.
June thru August … The meteorological summer period of June through August was wet and cool, with a total of 14.33 inches rain, compared to a normal of 9.81 inches. The first two weeks of June were very cool with 39 heating degree days recorded. There were 16 days of measurable rain of .01 inch or more in June, which tied the record for the month. July 2009 was the 5th coolest July on record, averaging 4.4 degrees below normal. Most of this was due to the average daily low of 58.7 degrees, which was the 2nd coolest average minimum on record for July. There were several fairly minor severe weather and heavy rain events causing localized urban flooding during the summer, which include the following… the late evening of July 7th, late evening of August 2nd, and from midnight to 2 am early on August 25th when there was 1.93 inches rain in two hours at the airport.
September 3rd … The heaviest rain event of the year was recorded early in the day with 3.10 inches rainfall from midnight CDT through 9 am. The rest of September was pleasant until October came along, which was cool, wet, and cloudy.
October and November … October was the wettest and the third coldest October on record. The average daily high of 53.3 degrees was the second coolest on record for October, and was 2.1 degrees cooler than the average daily high in November 2009. This is the first time on record that the average daily high in November was warmer than in October. Snowfall around an inch occurred on both the 10th and 12th. Measurable precipitation was recorded on 16 days of the month, adding up to 5.70 inches, or 3.71 inches above normal. November was a total turnaround from October, averaging 8.5 degrees above normal, tying 1913 for the 4th warmest November on record. And except for .80 inch of rain from the 23-24th, it was a dry but pleasant month.
December … The 1st of the month was the last nice day of the year with a high of 54 degrees. The first snowstorm of the month was 8.5 inches on the 8th. Then the big one hit over the Christmas holiday, putting a big damper on holiday travel and activities. The storm total snowfall of 20.7 inches from the evening of the 23rd to the 26th ranks in the top 3 snowstorms on record. The biggest storm on record was 22.9 inches April 9-10th 1913. The other big and more intense storm in the historical top 3 was 18.4 inches on March 15th 2004. The total snow for December 2009 at Sioux City was 34.0 inches. This breaks the previous December monthly record of 26.4 inches in 1897. However, it also breaks the all-time monthly record of 29.1 inches set in January 1982.
THE FOLLOWING TABLES GIVE A MONTH BY MONTH BREAKDOWN OF WEATHER IN 2009 AT THE SIOUX CITY AIRPORT...
AVERAGE DEPARTURE EXTREMES MONTHLY
MONTH MAX MIN MONTHLY FROM NORM HIGH LOW RECORDS
JANUARY 28.0 5.1 16.5 MINUS 2.1 47 20B
FEBRUARY 37.9 17.3 27.6 PLUS 2.5 59 0
MARCH 48.0 25.6 36.8 PLUS 0.3 76 4B
APRIL 60.4 35.8 48.1 MINUS 1.4 92 18
MAY 75.5 48.8 62.1 PLUS 0.9 97 34
JUNE 80.3 59.6 70.0 MINUS 0.5 94 44
JULY 81.7 58.7 70.2 MINUS 4.4 91 49 5TH COOLEST
AUGUST 81.9 58.3 70.1 MINUS 2.0 93 45
SEPTEMBER 76.4 52.1 64.2 PLUS 1.1 84 35
OCTOBER 53.3 35.4 44.3 MINUS 6.5 73 22 1TH WETTEST
NOVEMBER 55.4 31.1 43.2 PLUS 8.5 71 19 4TH WARMEST
DECEMBER 25.9 9.7 17.8 MINUS 4.5 54 13B 1ST SNOWIEST
2009 58.7 36.5 47.6 MINUS 0.7 97 20B
NORMAL YEAR 59.5 37.0 48.3
PRECIPITATION (INCHES) AND WINDS
DEPARTURE DEPARTURE MAX WIND GUSTS...
MONTH FROM NORM SNOWFALL FROM NORM DIRECTION/MPH/DATE
JANUARY .27 MINUS .32 5.1 MINUS 1.2 NW 52 ON 12TH
FEBRUARY .71 PLUS .09 2.7 MINUS 2.8 SW 53 ON 9TH
MARCH 1.44 MINUS .56 1.7 MINUS 4.1 SW 45 ON 23RD
APRIL 1.62 MINUS 1.13 0.5 MINUS 1.4 E 46 ON 15TH
MAY 1.00 MINUS 2.75 0 SW 52 ON 20TH
JUNE 5.26 PLUS 1.65 0 NW 47 ON 18TH
JULY 5.55 PLUS 2.25 0 NE 47 ON 7TH
AUGUST 3.52 PLUS .62 0 NW 52 ON 2ND
SEPTEMBER 4.56 PLUS 2.14 0 NW 48 ON 27TH
OCTOBER 5.70 PLUS 3.71 1.8 PLUS 1.0 N 44 ON 9TH
NOVEMBER .81 MINUS .59 trace MINUS 4.8 NW 43 ON 25TH
DECEMBER 2.38 PLUS 1.72 34.0 PLUS 27.7 NW 51 ON 25TH
2009 32.82 PLUS 6.83 45.8 PLUS 14.4 SW 53 FEB 9TH
RICHARD S. RYRHOLM...CLIMATIC FOCAL POINT