Winter Season (December 1, 2005 through February 28, 2006):
Temperatures -- January featured temperatures averaging 12 to 14 degrees above normal across the area. Peoria and Urbana each observed their warmest January on record. Average temperatures were above normal for approximately 45 consecutive days (December 22 through February 3). With such warm weather, the first real cold snap of the year did not arrive until mid February, with lows falling below zero on the 18th and highs struggling out of the single digits.
Weather -- The severe weather season got off to a fast start on January 2, when a microburst hit areas from Auburn to Chatham, in southern Sangamon County. Trees and pole barns were damaged along the 8 mile path, along with some minor house damage in Chatham. In addition, a tornado touched down in far southwest Shelby County near Oconee, with minor damage.
Strong winds affected much of the Midwest on January 24. Areas of central Illinois from Jacksonville, to Bloomington, to Decatur saw wind gusts in the 55 to 60 mph range.
A highly localized heavy snow event affected portions of central Illinois on February 11. Cold air aloft helped to produce intense snow showers, with Sangamon County hit hardest. The Springfield area received anywhere from 1 to 8 inches of snow, with the totals increasing from north to south across the city. A separate heavy snow band produced 7 inches in Pleasant Plains, but other areas of western Sangamon County saw nothing.
Extreme drought conditions affected portions of central Illinois as the year began, primarily north of a Monmouth to Peoria line, with severe drought conditions as far south as Springfield. The worst of the drought began to ease a bit early in the year, but severe drought conditions were still widespread west of I-55 by the end of February.
Spring Season (March 1 through May 31):
Temperatures -- While March was slightly above normal temperature-wise, April was significantly warmer than normal across the area. The warmest conditions affected the region from the 12-16th, when highs were well into the 80s, with lower 90s in a few parts of west central Illinois. After that, the next real heat wave did not arrive until the last several days of May, when highs reached the lower to mid 90s.
Weather -- The weather was extremely active during March and April. There were several events of note during the period.
The first event was on March 12, when a supercell thunderstorm which had originated in northeast Oklahoma moved across central Illinois during the evening. This cell produced a tornado which tracked for 66 miles across central Illinois, moving into the southern portions of Springfield, where the tornado was at F2 intensity. The path of this particular tornado was remarkably close to that of the F4 tornado of June 1957. A second tornado quickly formed after the initial one died, affecting eastern portions of Springfield. Strong tornadoes also occurred near Riverton and Mount Pulaski. A total of 9 tornadoes affected the Lincoln NWS coverage area during the outbreak, with 24 injuries but no fatalities. The responsible supercell did not finally die out until reaching far southern Michigan, a remarkable distance for a single supercell.
Not too long after that, a major winter storm impacted central Illinois on the 21st. Snow totals of 6 to 10 inches were common. In addition, blizzard conditions were observed across Scott, Morgan, Sangamon, Christian and Shelby Counties. The Lincoln NWS issued its first blizzard warning in its 10-year existence during the event.
April began with a major severe weather outbreak across the area. A total of 26 tornadoes were observed on April 2, two of which affected Springfield in nearly the same areas as the March 12 tornadoes. Extensive damage was observed in Taylorville due to a tornado which affected the western and northern portions of town. A tornado also passed just south of Decatur, but caused damage from Elwin to Long Creek.
Another round of severe weather occurred on Easter Sunday, April 16. Ten more tornadoes occurred across the area, but were concentrated a little further southeast than the other outbreaks. A pair of F2 strength tornadoes affected Effingham and Jasper Counties. While a pair of highly-photographed tornadoes also affected areas north of Mattoon, these were largely in open areas and did not cause as much damage.
By the end of May, a total of 61 tornadoes had been observed across central and southeast Illinois.
Increased amounts of rainfall largely brought an end to the drought across central Illinois by early May, although areas west of the Illinois River were still abnormally dry.
Summer Season (June 1 through August 31):
Temperatures -- Relatively cool conditions were noted through the first part of July, although there were a few days with highs in the lower 90s. However, hot and humid conditions were prevailing by the middle of July, with another heat wave beginning at the end of the month. Highs around 100 degrees were being observed in west central Illinois from July 31 through August 3, with lows in the mid to upper 70s. After this heat wave broke, temperatures the remainder of August trended below normal. By the 29th, highs in some areas were only in the 60s.
Weather -- A severe weather outbreak affected central Illinois on July 19. Originating in southeast Minnesota, this derecho affected central and western Illinois during the afternoon, before curving southwest. This storm system severely affected the St. Louis area, resulting in nearly a half million people being without power. In central Illinois, the storms were generally found west of a Bloomington to Taylorville line, producing wind gusts over 60 mph and hail up to the size of quarters.
Stationary thunderstorms on July 26 produced 6 inches of rain northeast of Decatur near Cisco. A number of weak tornadoes were also produced on this day, in areas between Decatur and Hoopeston. A couple weeks later, areas around Flora in southeast Illinois were affected by rainfall of 7 to 8 inches. Flora ended the month with just under 10 inches of rain.
Autumn Season (September 1 through November 30):
Temperatures -- Developing El Niño conditions led to a general trend of below normal temperatures, a typical result of such conditions during the autumn months.
While the first part of September saw temperatures generally slightly below normal, unseasonably cool conditions were found by the 19th. High temperatures north of I-72 generally failed to reach the 60 degree mark, during a time when normal highs are usually in the upper 70s.
After another significant but brief cold spell at the end of September, summer made one last gasp in early October. Highs in the lower to mid 90s were observed on October 2 and 3. Peoria broke its October high temperature record on the 3rd and Springfield tied theirs, both with highs of 93 degrees. Despite this, Springfield observed its 9th coolest October on record, as did Lincoln.
Cool conditions set up for the remainder of October and into the first part of November. Temperatures were frequently up to 20 degrees below normal, before an unseasonably warm spell set up for Thanksgiving week.
Weather -- After highs in the 90s nine days earlier, Springfield saw its first snowfall of the season on the 12th of October. This was the 5th earliest snowfall on record for the city, and the earliest snowfall since October 8, 1944.
The big event of the season began as November drew to a close. Widespread sleet and freezing rain affected locations west of I-57 on November 30. While initial ice accumulations were limited to trees and other exposed objects, eventually roads became icy as well. Some locations around Springfield received sleet for over 6 hours and accumulating over 2 inches, an unusual amount and duration for sleet. Ice accumulations on trees and power lines ranged from 3/4 inch to 2 inches thick by the end of the day in some areas. Widespread power outages affected more than 200,000 people in central Illinois, along with major damage to more than 20,000 trees, as a result of the ice.
Winter Season to date (December 1 to 18):
Temperatures -- The first several days of December were unseasonably cold, with a fresh snow cover helping to bring low temperatures even further downward. Peoria set a record low of 4 below zero on the 8th, and other locations along and west of the Illinois River fell below zero as well.
Mild weather returned to the region by the middle of December.
Weather -- The storm which began on November 30 continued to affect central Illinois on December 1, as the mixed precipitation eventually changed over to snow. Heavy snowfall of over a foot was common along and west of the Illinois river. Snowfall amounts over 6 inches were found as far east as I-55, with the snow tapering off sharply further east due to
the more prolonged icing situation. Much of east central and southeast Illinois only experienced rain during the event.
During the 3 day period from November 29 through December 1, precipitation totalled from 3 to 5 inches in many areas west of I-55. The heaviest totals were west of the Illinois River, in areas that had continued to see abnormal dryness lingering from the earlier drought.
Preliminary statistics for the 35-county Lincoln NWS coverage area: