WFO Chicago

2006 CLIMATE SUMMARY FOR ROCKFORD
                                  
                                Temperature                                                          Precipitation

Month
High
Low
Average
Departure
Total
Departure
Snow
Departure
January
39.5˚
27.5˚
33.5˚
+14.5˚
2.97”
+1.56”
5.1”
-5.2”
February
35.4˚
17.5˚
26.5˚
+1.8˚
0.66”
-0.68”
1.7”
-6.2”
March
45.9˚
28.0˚
37.0˚
+0.9˚
4.05”
+1.66”
6.2”
+0.6”
April
64.6˚
40.7˚
52.7˚
+4.8˚
4.60”
+0.98”
0.3”
-1.1”
May
70.0˚
49.3˚
59.7˚
+0.1˚
3.72”
-0.31”
0.0”
0.0”
June
78.5˚
56.7˚
67.6˚
-1.2˚
3.32”
-1.48”
0.0”
0.0”
July
85.4˚
64.9˚
75.2˚
+2.3˚
3.64”
-0.46”
0.0”
0.0”
August
82.4˚
62.2˚
72.3˚
+1.4˚
3.55”
-0.66”
0.0”
0.0”
September
70.8˚
50.8˚
60.8˚
-2.0˚
2.91”
-0.56”
0.0”
0.0”
October
57.6˚
38.0˚
47.8˚
-3.2˚
3.52”
+0.95”
T
-0.1”
November
50.3˚
32.5˚
41.4˚
+4.2˚
2.69”
+0.06”
0.1”
-2.5”
December
39.3˚
23.3
31.3
+6.9˚
2.52”
+0.46”
10.8”
0.0”
Total/Ave
60.1˚
41.1˚
50.6˚
+2.7˚
38.15"
+1.52"
24.2"
-14.5"

 
Yearly Extremes:
 
Highest Temperature:
96 degrees on July 17th and July 31st
 
Lowest Temperature:
 -11 degrees on February 18th
 
Most Precipitation in One Day:
1.71” on April 20th
 
Most Snowfall in One Day:
10.7” on December 1st
 
Records set during 2006:
 
Temperatures:
            Highs:
January 19th (53)
February 14th (59t)
 April 13th (83)
May 28th (93t)
December 17th (50t)
 
            Lows:
None
 
            Highest Lows:
May 28th (69)
November 27th (50)
November 28th (53)
December 31st (40t)
 
            Lowest Highs:  
None
 
            Monthly:
2nd Warmest January
9th Coldest October
 
            Seasonal:
None
 
Yearly:
11th Warmest Year (50.6)
 
Precipitation:
            One Day Precipitation:
January 28th (0.93”)
February 16th (0.43”)
December 21st (0.60”)
 
            Monthly Precipitation:
None
 
Seasonal Precipitation:
None
 
            One Day Snowfall:
October 11th (Trace-t)
December 1st (10.7”)
 
Monthly Snowfall:
None
 
            Seasonal Snowfall:
None
 
            Yearly:
None
 
 
JANUARY
The year started off very warm and ended up being the 2nd warmest January in Rockford’s history. Every day during the month was above normal for the average temperature. Of note were the unseasonably warm overnight temperatures as the minimum temperature rarely even got into the teens (only 5 times all month). The average temperature for the month ended up being over 14 degrees above the norm for January. The main precipitation event of the month occurred on January 20th 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. Rockford officially ended up with 5.0” of snow for the event. On the whole, precipitation for the month was above normal (twice as much as the normal amount) for the first time since February 2005!
 
FEBRUARY
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 16th 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 59 degrees on Valentine’s Day.
 
MARCH
The month of March was very average for temperatures, but well above normal for precipitation. The average maximum temperature was 0.4 degrees above normal, the average minimum temperature was 1.3 degrees above normal, the average temperature was 0.9 degrees above normal, and snowfall was 0.6 inches above normal. The amount of precipitation that fell during month was well above normal with 1.66 inches of surplus precipitation. There was a severe weather event on Sunday, March 12th. 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 66 degrees on the 11th and the lowest temperature was 14 on the 4th and 7th.
 
APRIL
April was a fairly warm month (12th warmest ever) with quite an active severe weather pattern. The main severe weather events occurred on the 2nd (mainly a hail event, with a few reports of damage from winds and F0 tornadoes), the 13th into the 14th (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. Rockford was well above normal for precipitation for the second month in a row. At this point of the year, the precip is over 3.50” in surplus of the average. Rockford was dropped from D2 severe drought conditions down to D0 which means abnormally dry. A record high of 83 was set on the 13th as well as a snowfall record of 0.3” on the 13th, but that precipitation came down as hail.
 
MAY
Temperature and precipitation wise, May ended up being as normal a month you can get. 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 a trace or more on 11 days in a row. 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 28th with a high of 93, which tied the previous record. A record high minimum was also set on the 28th with a low of 69. 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 24th, 29th, and 30th.
 
JUNE
June was a very normal month for temperatures, but rather dry for precipitation. The average temperature for the month was 1.2 degrees below normal and precipitation was 1.48” below normal. There were severe thunderstorm events on the 2nd, 17th, 19th, 21st and 26th. Probably the most notable event of the month was a heavy rain event that occurred during the overnight hours of the 25th into the 26th. There were no tornadoes that occurred during June and no records were broken. The warmest temperature of the month was 90 degrees on the17th and the coldest temperature was 45 degrees on the 12th. The most precipitation in one day occurred on the 10th when 1.52” fell (1.93” fell from the 9th thru the 11th).
 
JULY
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 13th through the 17th. The warmest day during this period was the 17th when the high got to 96 and the low only fell to 71. The second heat wave was longer and lasted into August. The warmest part of this heat wave came on the 31st where the high temperature was 96 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.
 
AUGUST
The beginning of August brought the end of the 2nd heat wave in the region. The highest temperature of the month occurred on the 1st at 94 degrees, while the lowest temperature of the month came later in the month on the 21st (52 degrees). A squall line went through early in the morning on the 3rd that created quite a bit of tree damage from Lee County all the way to downtown Chicago. Another round of morning severe storms rolled through on the 10th with some winds estimated at 70 mph. After the heat wave ended, temperatures returned to being more normal, but precipitation was scarce for the month until the last week.   Farmers had been having problems with their crops and the grass was brown and dying. 3.03” of the month’s 3.55” fell in the last week of the month to help with the abnormally dry conditions. Unfortunately, this was a sign of things to come in early September.
 
SEPTEMBER
This was the 5th month in a row that was below normal for precipitation, even though heavy rain fell on Labor Day that left a portion of the city of Rockford under water. Rainfall amounts were lighter at the airport than they were downtown where about 3 to 4 inches of rain fell in a rather short amount of time. This was in a very skinny band of rain that trained over the same area. A very strong rotation was also evident on radar as well as from trained weather spotters with the main storm. No tornados ever developed from the storm however. No records were set during September and the temperatures were 2.0 degrees below normal for the month. 
 
OCTOBER
The biggest event for the Rockford area in the month of October was the early season snowfall that happened on the 11th and 12th. A quick snow shower fell in the late evening of the 11th lead to a trace of snow at the airport. This tied a record for the most snow on that day. The main show came early in the morning on the 12th. Although the airport at Rockford only received a Trace of snow this day, a small band of snow developed along the north side of the city and extended through a portion of northern Illinois. Snowfall amounts of 1.0” to 2.0” were recorded throughout the area. This snow happened to coincide with the morning commute, so the early season snow caught some people off guard and caused a few car accidents. While most of northern Illinois had an active severe weather day on the 2nd, the Rockford area was mainly out of danger’s way on this day. Cold Canadian air persisted across the region for the second straight month, which leads to this October being the 9th coldest on Rockford’s record. 
 
NOVEMBER
For the most part of the month, temperatures were below or near normal with a few exceptions at the beginning and end of the month when temperatures were well above normal. Two records were set for warmest low temperatures on the 27th and 28th when temperatures didn’t drop below 50. The first warm streak ended abruptly on the 10th when a strong cold front came through and brought thunder and lightning to the region with thunderstorms out ahead of the front even though temperatures were in the mid 30s. The second warm spell came to an end on the last day of the month as a cold front pushed through, dropping temperatures into the 20s right before snow started on the 1st of December. Most of the precipitation for the month fell on three days. The first was on the 10th with the aforementioned front and the other two days were on the 28th and 29th before the end of the second warm streak.
 
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 1st 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. Six records were broken during the month: Highest Temperature on the 17th, most precipitation on the 21st, and most snowfall on the 1st (which also was the highest amount of snow to fall on one day in the month of December in Rockford’s history). With the warm end to the month, the High Minimum Temperature records were broken on the 29th, 30th and 31st.
 
Tim Halbach
Climate Focal Point
NWS Chicago

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