SIOUX FALLS AREA
CLIMATIC SUMMARY
2007

By Richard Ryrholm
Climatic Focal Point
National Weather Service, Sioux Falls

...MILD TEMPERATURES, WITH MORE FEAST OR FAMINE PRECIPITATION AT SIOUX FALLS IN 2007...

Temperatures averaged out to a mild 47.2 degrees in 2007, or 2.1 degrees above the normal of 45.1 degrees. It was the 10th straight year of above normal temperatures. The last below normal year was 1997 with an average temperature of 43.8 degrees. Precipitation totaled a respectable 31.34 inches in 2007, or 6.65 inches above average. However, a midsummer drought had a serious effect on area crops. Little severe weather affected the immediate Sioux Falls area in 2007, except for minor area flooding due to an occasional heavy rain.

The snow season of 2006-07 started late with only 4.1 inches snowfall through January 13th. Real winter finally materialized with 4.0 inches within 24 hours from January 14-15th. Then arctic air moved in with wind chills dropping as low as 25 below zero around 9 AM on the 15th, and the actual temperature bottoming out at -20 degrees at 7 AM on the 16th, for the coldest temperature of 2007.

February was the snowiest and coldest month of the winter with snowfall of 15.9 inches, and an average temperature of 13.6 degrees, or 7.2 degrees below normal. The main event in February was 5.7 inches snowfall recorded within 24 hours at Joe Foss Field on the 24-25th, starting as a mixture of sleet, freezing rain, and snow. Up to 7.5 inches of heavy wet snow was reported in southwest Sioux Falls.

March also came in like a lion with a blizzard from the 1st-2nd bringing 8.0 inches at the airport. However, after the first week, it was quite spring-like the rest of the month, and March averaged 6.4 degrees above normal. There was a big rain event the last day of the month with 3.27 inches at the airport for the heaviest precipitation event of 2007. The heavy rain caused some flooding of streets and basements in Sioux Falls in the afternoon of the 31st. Hail up to nickel size was also reported between 4:00 and 4:30 PM in the city. The monthly total precipitation of 4.97 inches was the wettest March since records began in 1893.

The big event of April was another heavy wet snowfall of 7.9 inches from the 10th-11th. The rest of the spring season from mid April through June 22nd was relatively warm with several heavy rain events, but real severe weather missed Sioux Falls. Up to 2.23 inches rain was reported in southwest Sioux Falls on April 22nd, but only .92 inch occurred at the airport where the official NWS gauge is located. Other official amounts were 1.69 inches May 4th-5th and 1.48 June 21st-22nd, which was the last measurable rain until 0.01 inch on July 12th, then 0.31 inch on July 18th. The 25 consecutive dry days with only 0.01 total precipitation was the 2nd driest growing season period on record in Sioux Falls, causing midsummer stress on area crops. The driest period on record was 0.01 inch in 26 days from July 23rd to August 17th in 1971. There was hail up to one inch in diameter reported in Sioux Falls the evening of July 17h, but the precipitation missed the airport. July 2007 ended up as the 3rd driest July on record with only 0.32 inch rainfall. The hottest temperature of 2007 was 98 degrees on July 7th.

However, fitting the typical feast or famine pattern in recent years, August totally flipped around to very wet with a total of 6.18 inches, for the 9th wettest August on record. The main event in August was a drought-busting 2.48 inches on the 4th.

The first official freezing temperature of the fall season was a low of 30 degrees at the airport on September 15th, with only a little frost in the area. However, widespread freezing temperatures did not occur until late October, starting with 29 degrees recorded on the 26th, prolonging the growing season for many people with gardens in the area. If not for the low on September 15th, it would have been the 2nd longest above freezing period on record with 193 days from April 15th to October 26th. The most consecutive above freezing days on record was 196 days from April 9th to October 23rd 1938.

October was another wet month with 5.98 inches total. Of this, 1.61 inches was measured on the 7-8th, and 3.52 inches occurred in the 5 day period from 13th to the 18th. The pattern reverted back to extremely dry with only a trace precipitation in the 38 day period from October 22nd through November 28th.

The change of month to December brought a winter storm to the area on December 1st, with 4 to 5 inches of heavy wet snow mixed with sleet and freezing rain. Except for periods of fog, the weather was uneventful until 4.9 inches of snow on Christmas Day, for the 2nd heaviest Christmas snowfall on record. The biggest snowfall ever on Christmas was 10 inches in 1945.  The fog was most prevalent during the last half of the month, with 8 days of dense fog reported at the Sioux Falls airport.

THE FOLLOWING TABLES GIVE A MONTH BY MONTH BREAKDOWN OF WEATHER IN 2007 AT THE SIOUX FALLS AIRPORT...

TEMPERATURES

                 AVERAGE             DEPARTURE  EXTREMES    MONTHLY
MONTH MAX MIN MONTHLY FROM NORM HIGH LOW RECORDS

JANUARY 26.8 10.2 18.5 PLUS 4.5 45 20B
FEBRUARY 21.1 6.1 13.6 MINUS 7.2 46 15B
MARCH 49.1 28.9 39.0 PLUS 6.4 75 2 1ST WETTEST
APRIL 57.2 33.8 45.5 MINUS 0.2 92 14
MAY 74.0 50.7 62.4 PLUS 4.6 88 34
JUNE 80.5 59.3 69.9 PLUS 2.4 93 46
JULY 87.2 62.8 75.0 PLUS 2.0 98 46 3RD DRIEST
AUGUST 82.1 63.0 72.6 PLUS 1.8 92 51 9TH WETTEST
SEPTEMBER 76.2 50.8 63.5 PLUS 2.6 90 30
OCTOBER 64.4 42.5 53.4 PLUS 5.4 88 26 3RD WETTEST
NOVEMBER 45.9 24.2 35.0 PLUS 3.8 65 2 8TH DRIEST
DECEMBER 26.2 8.8 17.5 MINUS 0.8 38 6B

2007 57.6 36.8 47.2 PLUS 2.1 98 20B
NORMAL YEAR 57.2 33.0 45.1

PRECIPITATION AND WINDS

                   DEPARTURE             DEPARTURE    MAX WIND GUSTS... 
MONTH FROM NORM SNOWFALL FROM NORM DIRECTION/MPH/DATE

JANUARY .45 MINUS .06 8.1 PLUS 0.7 NW 51 ON 9TH
FEBRUARY 1.29 PLUS .78 15.9 PLUS 10.0 SE 44 ON 23RD
MARCH 4.97 PLUS 3.16 8.0 MINUS 0.1 NW 43 ON 1ST
APRIL 1.93 MINUS .72 8.2 PLUS 4.7 NW 40 ON 3RD
MAY 2.63 MINUS .76 0 SE 54 ON 5TH
JUNE 3.98 PLUS .49 0 S 53 ON 6TH
JULY .32 MINUS 2.61 0 NW 43 ON 10TH
AUGUST 6.18 PLUS 3.17 0 S 49 ON 11TH
SEPTEMBER 2.27 MINUS .31 0 S 53 ON 29TH
OCTOBER 5.98 PLUS 4.05 0 MINUS 1.1 NW 43 ON 2ND/30TH
NOVEMBER .04 MINUS 1.32 0.6 MINUS 7.0 NW 46 ON 28TH
DECEMBER 1.30 PLUS .78 11.4 PLUS 4.4 W 43 ON 14TH

2007 31.34 PLUS 6.65 52.2 PLUS 11.6 SE 54 MAY 5TH

RICHARD S. RYRHOLM...CLIMATIC FOCAL POINT

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