Sioux Falls 2009 Climate Summary




700 PM CST FRI JAN 1 2010




It was an interesting temperature pattern in 2009, varying from a fairly mild winter and spring to unusually cool summer to a seesaw fall to winter, but the yearly average was almost exactly normal at 45.1 degrees. Precipitation for the year of 23.06 inches at the Sioux Falls airport was slightly below the normal of 24.69 inches. However, yearly precipitation was quite a bit higher west to just south of Sioux Falls with up to 30 inches total precipitation.


January was near normal in temperature and snowfall, and continued the very wintry conditions from December 2008. A couple of snow events, 2.1 inches on the 9-10th and 3.7 inches on the 12-13th, pushed the snow depth to 6 inches. In the afternoon of the 12th, strong northerly winds gusted up to 50 mph and caused blizzard conditions in open areas around Sioux Falls. On the 14th, bitter cold arctic air plunged into the area with wind chills in the 20s below zero dropping to near 40 below zero by late evening. Then January 15th was the coldest day of the winter and the year with a minimum of 26 below and a record low maximum for the day of 4 below. The low of -26 was the lowest temperature since –29 on February 2nd 1996. The last time the daily high was lower than –4 was on January 29th 2004 with a high of –5.


The rest of the winter was really not that bad except for a couple of really cold days, and snowfall was well below average. There was only 6.3 inches total snowfall from January 14th through April 3rd. On February 9th, a monthly record low barometric pressure of 28.97 inches occurred with the passage of a storm system, but it was mild enough for just rain up to a third of an inch in the area. Another event worth mention in February was the mixed winter precipitation on the 26-27th, with up to 3 inches snowfall in the area. Another 3 inches or so snowfall occurred in Sioux Falls March 8-10th.


Official spring started with a bang March 22-23rd with up to an inch of rain along with some severe weather the late afternoon of the 23rd. Localized thunderstorm wind gusts of 70 mph were reported from southwest Sioux Falls to north of Tea. On March 31st, a winter storm totally missed Sioux Falls to the west with over a foot snowfall at Mitchell, but with only 1 to 2 tenths of an inch of rain in Sioux Falls. However, the snow season was not over yet as a very strong low pressure system moved over Nebraska and southern Iowa from April 4-5th, giving the Sioux Falls area 6.5 to 8 inches snowfall and north to northeast winds gusting to 35 to 40 mph. The 6.5 inches of snow within 24 hours at the Sioux Falls airport was the biggest snowfall of the 2008-09 winter.


The rest of April and May was rather uneventful. On April 23rd, the temperature spiked up to 91 degrees for a record high for the date, beating the old record of 87 set in 1939. Temperatures also broke 90 degrees May 19th and 20th, but temperatures were only to reach 90 two more times in 2009, on June 22nd and August 12th. The high of 95 degrees on May 19th was the warmest temperature in 2009.


The meteorological summer of June through August was the 8th coolest summer since records began in 1893 with an average temperature of 67.5 degrees. June was not only cool, especially in the first half of the month, but rainy, and it tied a June record of 16 days with measurable rain. July 2009 was the 4th coolest July on record with an average of 68.6 degrees, or 4.4 degrees below normal. The average daily high of 79.5 degrees tied 1950 for the third coolest average maximum on record for July. There were no 90 degree days in July 2009, and only 3 other Julys since 1893 had no 90 degree days. Summer precipitation ended up slightly below normal at the Sioux Falls airport with 8.71 inches. However, most of Sioux Falls, especially south parts of town had quite a bit more, with 14.04 inches rain recorded 6 miles south of the airport in far southern Sioux Falls.


There were a number of severe weather events in the area during the summer, but most of the really severe weather and heavy rain events missed the Sioux Falls area to the west and south. On June 23rd, thunderstorm wind gusts up to 60 mph were reported in the area, mainly just west and northwest of the city around 10 AM. In the evening of June 24th, a tornadic supercell storm system with large hail moved from southwest of Huron through McCook and Turner counties. Tornadoes tracked from near Bridgewater to near Parker to Viborg from about 1030 to 1130 PM CDT. In the first couple of weeks of July, several thunderstorm and heavy rain events affected the Sioux Falls area. On July 3-4th, around an inch of rain occurred in Sioux Falls, but 2 to 3 inches was recorded west to southwest of the city from Salem to Parker. In the early evening of July 7th, thunderstorms with hail up to golf ball size occurred in the area. Heavy rainfall up to around 2.5 inches in central Sioux Falls caused urban flash flooding in the city. Then on July 9th, mainly morning thunderstorms in the area brought one inch hail again from McCook to Lincoln counties. On the afternoon of July 14th, severe thunderstorms skirted north and east of Sioux Falls this time, with one inch hail and winds up to 70 mph reported from near Flandreau and Brookings to southwest Minnesota.


August continued the cool summer and was on the dry side, especially near the official gauge at the airport. Up to an inch of rain occurred in Sioux Falls in the early morning of the 19th, and there was some severe weather in the afternoon with hail up to an inch diameter near Canton. On the 25th there was a classic example of the airport missing the heavy rain with only a quarter inch compared to as much as 1.22 inches in southwest Sioux Falls. September was a mild and dry month. The main heavy rain event again tracked west of Sioux Falls, from DeSmet through Salem and Parker to Sioux City with a band of 1 to 3 inches of rain early on September 3rd.


October was unusually wet, cloudy, and cold, as it was the 4th coldest, the 5th wettest, and the 10th snowiest October on record. October was officially the wettest month of 2009 with 5.52 inches precipitation, or 286 percent of normal. There were two early season snow events… 1.4 inches on the 9th and 2.1 inches on the 11-12th, with 3 record low daily high temperatures in the upper 30s from the 10th to the 13th. It was the coldest first two weeks of October ever recorded, with an average of 40.9 degrees. November was a total turnaround from October, averaging a whopping 10 degrees above normal, for the 4th warmest November on record. What was amazing is that the average daily high temperature for November was warmer than in October, by 3.1 degrees. There has been only one other year in history that this has happened, and that was October 1917. It was also very dry in November with only .17 inch precipitation, and it looked like it might be a nice El Nino winter, but it all changed again in December.


The 1st of December with a high of 51 degrees, was the last nice day of the year. On December 8th, the first storm of the winter gave 5 to 6 inches snowfall to the area. Then the big one hit over the Christmas holiday, putting a big damper on holiday travel and activities. From the evening of December 23rd through Christmas to the 26th, there was a storm total snowfall of 19.0 inches at the Sioux Falls airport. This is the 4th biggest storm total snowfall on record. The heaviest snowfall within a 24 hour period for this storm was 12.1 inches from the evening of the 24th into Christmas Day, for the 12th heaviest 24 hour snowfall on record. It was also the snowiest Christmas Day on record with 10.5 inches for the calendar day. The monthly snowfall of 27.8 inches was the 5th snowiest month on record and the 2nd snowiest December on record, next to the 41.1 inches in 1968. The 19 inch snow depth at the end of the month was the most snow on the ground since 22 inches snow depth on February 6th 2004.     






                 AVERAGE             DEPARTURE  EXTREMES    MONTHLY



JANUARY        24.2   4.4     14.3    PLUS 0.3   52  26B

FEBRUARY       34.6  12.7     23.7    PLUS 2.9   57   6B

MARCH          43.9  22.9     33.4    PLUS 0.8   70   7B

APRIL          56.8  33.8     45.3   MINUS 0.4   91  18

MAY            71.4  45.9     58.6    PLUS 0.8   95  35

JUNE           75.8  55.9     65.8   MINUS 1.7   90  40

JULY           79.5  57.7     68.6   MINUS 4.4   87  50   4TH COOLEST

AUGUST         78.7  57.2     68.0   MINUS 2.8   91  41

SEPTEMBER      74.6  52.3     63.4    PLUS 2.5   84  35  

OCTOBER        49.7  35.2     42.4   MINUS 5.6   65  21   4TH COLDEST

NOVEMBER       52.8  29.7     41.2   PLUS 10.0   70  17   4TH WARMEST

DECEMBER       23.1   7.0     15.1   MINUS 3.2   51  10B  2ND SNOWIEST


 2009          55.4  34.6     45.0   MINUS 0.1   95  26B

NORMAL YEAR    57.2  33.0     45.1




                   DEPARTURE             DEPARTURE    MAX WIND GUSTS...



JANUARY     .32   MINUS  .19      6.5    MINUS 0.9      SW 47 ON 22ND

FEBRUARY    .41   MINUS  .10      2.6    MINUS 3.3      SE 44 ON 9TH 

MARCH      1.31   MINUS  .50      3.2    MINUS 4.9      SE 46 ON 30TH

APRIL      1.95   MINUS  .70      6.6     PLUS 3.1       N 45 ON 20TH 

MAY        1.43   MINUS 1.96       0                     S 46 ON 20TH

JUNE       3.07   MINUS  .42       0                    NW 49 ON 19TH

JULY       3.71    PLUS  .78       0                    NE 41 ON 7TH  

AUGUST     1.93   MINUS 1.08       0                     W 39 ON 16TH

SEPTEMBER  1.21   MINUS 1.37       0                    NW 47 ON 27TH 

OCTOBER    5.52    PLUS 3.59      3.5     PLUS 2.4      NW 38 ON 30TH

NOVEMBER    .17   MINUS 1.19    trace    MINUS 7.6      NW 39 ON 25TH

DECEMBER   2.03    PLUS 1.51     27.8    PLUS 20.8       N 46 ON 9TH 


 2009     23.06   MINUS 1.63     50.2    PLUS  9.6      NW 49 JUN 19TH




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