National Weather Service Weather Forecast Office

 

Highest Temperature:

99 degrees on July 31^st & August 1st

 

Lowest Temperature:

-7 degrees on February 18^th

 

Most Precipitation in One Day:

2.05” on July 20^th

 

Most Snowfall in One Day:

5.8” on December 1^st

Temperatures:

 

            Max:

July 31^st (99 Tie)   

 

            Min:                             

April 26^th (27)

May 22^nd (36)

 

            Highest Min:

May 28^th (74)

August 1^st (80)

November 27^th (52)

November 28^th (54)

December 31^st (43 Tie)

 

            Lowest Max:   

December 3^rd (15)

 

            Monthly:

3^rd Warmest January

9^th Warmest April

11^th Coldest October

 

            Seasonal:

None

 

Yearly:

10^th Warmest (52.0)

 

Precipitation:

 

            One Day Precipitation:

September 22^nd (1.73”)

October 2^nd (1.39”)

November 29^th (1.73”)

December 1^st (1.23”)

December 22^nd (0.90”)

 

            Monthly Precipitation:

14^th Wettest September (5.85”)

 

Seasonal Precipitation:

12^th Wettest Fall (12.50”)

 

            One Day Snowfall:

October 12^th (0.3”)-Earliest Measurable Snow in Chicago History

 

Monthly Snowfall:

None

 

            Seasonal Snowfall:

None

 

            Yearly:

18^th Wettest Year (41.90”)

 

The year started off very warm and ended up being the 3^rd warmest January in Chicago’s history. Every day for the month ended up above normal for the average temperature. Of note was the unseasonably warm overnight temperatures as the minimum temperature rarely even got into the teens (only twice all month). The average temperature for the month ended up being about 14 degrees above the norm for January. The main precipitation event of the month occurred on January 20^th when a developing system created an intense band of snow and thundersnow. Snowfall rates were very high and most of the snow fell within a 6 hour period during the evening hours. Some stations reported 13 inches of snow in 6 hours. The line between snow and rain pretty much split the region, as most of the northeastern counties in Illinois had rain/sleet/snow mix through most of the early portion of the event and ended up with a few inches. O’Hare officially ended up with 4.1” of snow for the event. On the whole, precipitation for the month was above normal for the first time since February 2005!

 

February was the month where all the storm systems seemed to go to our north, leaving the region without much snowfall to speak of. The most notable case was on the 16^th where a frontal boundary set up just to the south of the region. Severe weather was reported in the area, with a possible tornado touchdown in Iroquois county (Wisconsin had thundersnow and blizzard conditions on this day). After this event, high pressure settled in for the rest of the month and created dry conditions. The average temperature and precipitation amount for the month was right around average, but snowfall was once again below normal. The highest temperature for the month was 56 degrees on Valentine’s Day.

 

The month of March was pretty much as average as you can get. The average maximum temperature was 0.6 degrees above normal, the average minimum temperature was 1.4 degrees above normal, the average temperature was 1.0 inches above normal, precipitation was 0.05” above normal and snowfall was -0.3 inches below normal. There was a severe weather event on Sunday, March 12^th. Quite a bit of hail was reported with this system and some damage was reported in the Bridgeview area which may have been caused by a microburst. With the near normal precipitation conditions and no snow pack to melt, the drought continues on for most of northern Illinois. The highest temperature for the month was 70 degrees on the 30^th and the lowest was 20 on the 3^rd and 7^th.

 

 

April was a fairly warm month (9^th warmest ever) with quite an active severe weather pattern. The main severe weather events occurred on the 2^nd (mainly a hail event, with a few reports of damage from winds and F0 tornadoes), the 13^th into the 14^th (large hail) and Easter Sunday (a few Tornadoes). There was also substantial flooding with the storms on Easter with some reports of 3 to 5 inches or more in some areas. Rainfall totals for the month were right around normal, helping to improve drought conditions as this was the 4^th straight month with totals at or above normal. Chicago was dropped from D2 severe drought conditions down to D0 which means abnormally dry. A record low was set at Chicago with 27 on the morning of the 26^th.

 

Temperature and precipitation wise, May ended up being a very normal month. A cut-off low pressure system was stuck in the western Great Lakes for about a week and a half and created quite a cool streak during the middle part of the month. It also created a bit of wet streak, as there was precipitation of 0.01” or more on 9 days in a row. This was good for the 5^th longest record in Chicago’s history for any time period. Even though there were a lot of days with rain, the amounts tended to be small. As the low moved on, the atmosphere went back toward normal and beyond. The warmest temperature of the month occurred on the 28^th with a high of 92. A record high minimum was also set on the 28^th with a low of 74. There were a few severe episodes, mainly with pulse thunderstorms. One tornado occurred in Kankakee County, 3 miles south of Aroma Park and was rated an F1. Flooding also occurred in most of the counties in northern Illinois on the 24^th, 29^th, and 30^th.

 

As was the case in May, June was a very normal month for temperatures and precipitation. The average temperature for the month was 0.1 degrees above normal and precipitation was 0.42” above normal. There were a few severe thunderstorm events on the 2^nd, 17^th, 19^th, 21^st and 26^th. Probably the most notable event of the month was a heavy rain event that occurred during the overnight hours of the 25^th into the 26^th. The observer at Midway 3SW reported 1.15” of rain in 15 minutes. There were no tornadoes that occurred during June and no records were broken. The warmest temperature of the month was 92 degrees on the17th and the coldest temperature was 48 degrees on the 5^th. The most precipitation in one day occurred on the 10^th when 1.58” fell (1.66” fell from the 25^th thru the 26^th).

 

The main weather story in July was the two heat waves that we went through. The first wave of 90+ temperatures occurred from about the 13^th through the 17^th. The warmest day during this period was the 15^th when the high got to 97 and the low only fell to 74. The second heat wave was longer and lasted into August. The warmest part of this heat wave came on the 31^st into the 1^st where a maximum temperature record was tied on the 31^st (99 degrees) and a high minimum temperature was tied on Aug 1^st (80 degrees).   With the warm weather, severe winds were prevalent whenever a cold front would push through to cool things off. There were no tornadoes during July, but on the 27^th there were some funnel clouds that occurred in Will County. There was also quite a bit of heavy rain in Will County on the 27^th with some reports of 5.50” of rain in 90 minutes. On the 30^th, a few storms rolled through the Chicago Harbor and knocked over 7 sailboats participating in a race.

 

The beginning of August brought the end of the 2^nd heat wave in the region. A record high minimum was set on 1^st of 80 degrees. An 80 degree minimum temperature is a rarity in Chicago as we average about one every 5 years. The last 80 degree minimum occurred on July 14^th, 1995. A squall line went through early in the morning on the 3^rd that created quite a bit of tree damage from Lee County all the way to downtown Chicago. After the heat wave ended, temperatures returned to being more normal, but precipitation was scarce as there was a deficit of 1.67”.   This was the largest deficit since the 2005 drought. The highest temperature of the month occurred on the 1^st (99 degrees) and the lowest temperature occurred on the 21^st (55 degrees).

 

This September was the 14^th wettest September on record for Chicago. The main weather story for the month was the flooding that occurred on the 13^th. Southern Cook county and Lake county Indiana received about 3-4 inches of rainfall, with portions of Highland, Indiana getting up to almost 8 inches of rain. Most of this fell in about a 3-5 hour period in the morning. About 10 people had basements collapse with many more with water standing in their basement. Flooded viaducts around the south side of Chicago stranded motorists that tried to drive through it. A close call also happened on the 22^nd when three distinct supercell thunderstorms developed in northern Illinois and tracked through northern Cook County. A tornado was confirmed with one storm that went through the campus of Loyola University and over Lake Michigan. Numerous hail and wind damage reports came from these and other storms throughout the day. A record amount of rain fell at O’Hare on this day as well, with 1.73 inches falling. Temperatures were below normal for the month for the first time in 2006.

 

 

The 4^th of October was one of the largest warned severe weather events in the history of the National Weather Service in Romeoville. About 43 severe thunderstorm or tornado warnings were issued with almost all of them verified with hail or wind damage. The day began with a cluster of storms moving eastward across northeastern Illinois into northwestern Indiana. As these storms were weakening and moving east, a mesoscale convective system in southern Wisconsin quickly developed and left a swath of damage from the Wisconsin/Illinois border southward all the way through the NWS’s county warning area that extends to Iroquois, Ford, and Livingston counties. One of the hardest hit areas was southern Cook County in the towns of Hickory Hills (where a roof was blown off of a school gym and toppled a service van), Palos Hills and Bridgeview. Two records were set during the month. The first was for the most precipitation for the 2nd with 1.39 inches at O’Hare. The second was for the earliest measurable snow in Chicago’s history. 0.3” of snow fell on the 12^th, which also broke the record for the most snow on that day. The average temperature for the month of 49.0 was the 11^th coldest, which has continued from the September trend of being cold despite the fact that El Nino conditions exist in the eastern tropics of the Pacific, which tends to lead towards warmer temperatures.

 

The month of November was a month of extremes…kind of. While temperatures were below normal for most of the month, a warm spell at the end of the month, that lead to two highest minimum records being broken on the 27^th and 28^th, caused the average temperatures to be right around normal. There was a stretch in the middle part of the month where the high temperature was in the 40s for 12 days in a row. As for precipitation, there were two days when over an inch of rain fell (10^th and 29^th) which accounted for most of the rain for the month. The rainfall on the 29^th was a record for that day. There were two days of snow during the month: a trace on the 10^th on the backside of a cold front and on the 30^th when 0.4” fell before midnight with the first big snowfall of the season. Most of that snow fell on the 1^st of December. 

 

December 2006 had a lot of similarities to December 2005 due to a snowstorm in the beginning part of the month, followed by a cold spell for about a week and a half, followed by above normal temperatures the rest of the month. The heaviest snowfall of the year came on the 1^st when a swath of 6-13 inches of snow fell across northern Illinois. The snow fell mainly during the morning rush hour on that Friday, but due to the advance warning, most people took off from work or had school cancelled in advance. This Christmas was once again not white, but above normal for temperatures again with no snow cover left from the early snowstorm. Four records were broken during the month: Lowest Max on the 3^rd, most precipitation on the 1^st and 22^nd, and High Min tied on the 31^st.

 

Tim Halbach

Climate Focal Point

NWS Chicago