SIOUX CITY AREA
CLIMATIC SUMMARY
2006

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

...ANOTHER WARM YEAR...BUT INCONSISTENT PRECIPITATION AT SIOUX CITY IN 2006...

Temperatures averaged 50.7 degrees for 2006, or 2.4 degrees above the normal of 48.3 degrees. This was the 9th straight year of above normal temperatures in the Siouxland. The last year below normal was in 1997 with an average of 47.5 degrees. Precipitation totaled 27.34 inches at the Sioux Gateway Airport, or 1.35 inches above average. However, the precipitation was quite inconsistent in 2006, especially during the critical growing season from May through July, when only 4.46 inches of rainfall was recorded, or 6.20 inches below the normal of 10.66 inches. The following is a chronological account of the weather events of 2006 in Siouxland... 

January...Temperatures averaged 33.5 degrees, or 14.9 degrees above normal, for the warmest January since records began at Sioux City in 1889. This beat the old monthly record of 31.4 degrees set in 1933. There was a record winter streak of 52 days of daily maximums of at least 30 degrees from December 21, 2005 through February 10, 2006. This shattered the old record of 29 days straight from January 15th to February 12th in 1931. A record daily high of 64 degrees occurred on January 15th. Nighttime lows were also mild during the period. From December 22nd through February 4th, there was a record 45 days in a row in which the daily low was at least 10 degrees. The old record was 42 days from January 19th to February 29th in 1992.

February 16th...4.4 inches of snowfall was accompanied by north winds gusting around 30 mph causing areas of blowing and drifting snow. The lowest temperature of 2006 occurred two days later on the 18th, when the mercury bottomed out at 14 below zero. 

March 7th...Early season severe weather produced some penny size hail in the area in the late morning, but up to 1.5 inch diameter hail was reported at Bronson.

March 20-21st...The heaviest snowfall of 2006 of 7.5 inches was recorded on March 20th...with a two day total of 9.2 inches. Winds gusted to 37 mph at the airport, causing near blizzard conditions in the area and closing schools and businesses.

March 30th...Severe weather and heavy rain hit the area in the afternoon with 1.03 inches rainfall at the airport. In Sioux City, thunderstorm winds gusting near 80 mph destroyed a large storage building. A small tornado about a mile east of Sioux City at 355 PM CST blew the roof off a house and moved it off its foundation. The official strongest wind of 2006 at the airport was 60 mph out of the west at 348 PM CST.

April 6th...Hail up to nickel size was reported in Sioux City at 828 PM CDT.

April 13th...The afternoon high temperature of 91 degrees was not only a record high for the date, but it was the 4th earliest date Sioux City has seen 90 degrees. The earliest 90 degree day on record was on March 30, 1968, when the high was 91 degrees.

April 28-30th...In the last three days of April, rainfall at the airport totaled 2.16 inches, which was the last significant rainfall until June 16th.

May through the first half of June...was the driest May through June 15th period on record with 1.06 inches rainfall at the airport, compared to a normal of 5.58 inches. The previous driest such period was 1.88 inches in 1989. It was also the third driest May on record with 0.87 inch precipitation. During the period, there were two notable record daily highs, with 98 degrees on May 28th and 100 degrees on June 9th.

June 16th...Heavy rains in the late afternoon and evening relieved the very warm and dry conditions, but caused flash flooding of roads and low areas in and east of Sioux City. 2.76 inches precipitation was recorded at the airport for the heaviest event of the year, with 3.65 inches reported at the north end of Sioux City.

July reverted back to hot and dry weather for the Siouxland. It was the second driest July on record with only 0.36 inch of rain, compared to a normal 3.30 inches. There were 17 days with a high temperature of 90 degrees or above, compared to a normal of 9 days in July. This obviously put a lot of stress on area crops.

August made a welcome quick turnaround in the weather department with 1.55 inches rainfall in the first two days, ending up with 6.98 inches for the month, or 4.08 inches above normal. The heaviest event recorded at the airport was 1.94 inches within 24 hours from the 10-11th. 

September continued the wet conditions with a total of 5.45 inches for the month. The heaviest 24 hour precipitation was 2.07 inches on the 21st-22nd. It was also overall cooler than normal from late August through September and October.  Below normal temperatures have been unusual in the last several years, as 22 of the 24 months from September 2004 through August 2006 were at or above normal.

November and December returned to the above normal temperatures, which seems to be a more frequent occurrence in the winter season. What was most unusual was that most of the precipitation in the second wettest December on record was from rain, not snow. How this pans out the rest of the winter season remains to be seen...

THE FOLLOWING TABLES GIVE A MONTH BY MONTH BREAKDOWN OF WEATHER IN 2006 AT THE SIOUX CITY AIRPORT...

TEMPERATURES

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

JANUARY 43.8 23.1 33.5 PLUS 14.9 64 11 1ST WARMEST
FEBRUARY 37.9 12.3 25.1 ZERO 60 14B
MARCH 46.5 24.8 35.7 MINUS 0.8 66 4
APRIL 67.1 40.7 53.9 PLUS 4.4 91 27
MAY 76.2 50.5 63.3 PLUS 2.1 98 35 3RD DRIEST
JUNE 85.4 59.1 72.2 PLUS 1.8 100 49
JULY 90.4 64.7 77.6 PLUS 3.0 102 51 2ND DRIEST
AUGUST 83.4 62.1 72.8 PLUS 0.7 94 49 6TH WETTEST
SEPTEMBER 70.9 48.4 59.6 MINUS 3.5 89 32 8TH COOLEST
OCTOBER 60.2 35.8 48.0 MINUS 2.8 93 13
NOVEMBER 49.7 24.0 36.8 PLUS 2.0 82 3
DECEMBER 40.7 19.6 30.2 PLUS 7.9 58 1 2ND WETTEST

2006 62.7 38.8 50.7 PLUS 2.4 102 14B

NORMAL YEAR 59.5 37.0 48.3

PRECIPITATION AND WINDS

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

JANUARY .24 MINUS .35 0.6 MINUS 5.7 NW 56 ON 24TH
FEBRUARY .38 MINUS .24 6.4 PLUS 0.9 NW 38 ON 10TH
MARCH 2.61 PLUS .61 11.0 PLUS 5.2 W 60 ON 30TH
APRIL 3.37 PLUS .62 0 MINUS 1.9 S 56 ON 6TH
MAY .87 MINUS 2.88 0 W 47 ON 24TH
JUNE 3.23 MINUS .38 0 S 43 ON 15TH
JULY .36 MINUS 2.94 0 S 31 ON 31ST
AUGUST 6.98 PLUS 4.08 0 SW 37 ON 10TH
SEPTEMBER 5.45 PLUS 3.03 0 S 36 ON 16TH
OCTOBER .82 MINUS 1.17 0.3 MINUS 0.5 NW 45 ON 30TH
NOVEMBER .47 MINUS .93 0.5 MINUS 4.3 NW 36 ON 28-29TH
DECEMBER 2.56 PLUS 1.90 1.8 MINUS 4.5 W 38 ON 14TH

2006 27.34 PLUS 1.35 20.6 MINUS 10.8 W 60 MAR 30TH

RICHARD S. RYRHOLM..CLIMATIC FOCAL POINT

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