May and Meteorological Spring 2021 Climate Summary and Lack of Severe Weather in Perspective

Overview & Graphics

Chicago and Rockford Monthly Summary

Public Information Statement
National Weather Service Chicago IL
119 PM CDT Tue Jun 1 2021 /219 PM EDT Tue Jun 1 2021/

...A Look Back at the Climate for the Month of May 2021 for
Chicago and Rockford...

At Chicago, the average high temperature was 69.7 degrees, which
is 0.8 degrees below normal. The average low temperature was 50.8
degrees, which is 0.2 degrees above normal. The average temperature
for the month was 60.2 degrees, which is 0.4 degrees below normal.
During the month of May, 1.79 inches of precipitation were recorded,
which is 2.70 inches below normal.

There were no daily or top ten monthly records set for Chicago
during the month of May 2021.


At Rockford, the average high temperature was 71.3 degrees, which
is 0.1 degrees above normal. The average low temperature was 50.2
degrees, which is 0.7 degrees above normal. The average temperature
for the month was 60.8 degrees, which is 0.4 degrees above normal.
During the month of May, 2.36 inches of precipitation were recorded,
which is 1.82 inches below normal.

One daily record for Rockford was set and two were tied during the
month of May 2021:
* Tied record daily maximum temperature of 88 on the 1st.
* Tied record daily highest minimum temperature of 61 on the 2nd.
* Record daily highest minimum temperature of 70 degrees on the
  25th.

There were no top ten monthly records set for Rockford during the
month of May 2021.

$$

Latest Monthly Climate Report:   Chicago   |   Rockford  

Chicago and Rockford Seasonal Summary

Public Information Statement
National Weather Service Chicago IL
421 PM CDT Tue Jun 1 2021 /521 PM EDT Tue Jun 1 2021/

...A Look Back at the Climate for Meteorological Spring (March,
April, May) 2021 for Chicago and Rockford...

At Chicago, the average high temperature for the spring season was
61.4 degrees, which is 2.6 degrees above normal. The average low
temperature was 42.8 degrees, which is 2.2 degrees above normal.
The mean temperature for the season was 52.1 degrees, which is 2.4
degrees above normal.

A total of 3.75 inches of precipitation was recorded during this
past spring, which is 6.94 inches below normal. In addition, a
total of 1.8 inches of snow fell, which is 5.0 inches below
normal.

Records established or tied during the spring months:

March:
* Tied record daily maximum temperature of 69 degrees on the 9th.
* Record daily highest minimum temperature of 57 degrees on the 10th.
** 10th warmest March on record since 1871 with a mean average
   temperature of 44.2 degrees.

April:
* Tied record daily maximum temperature of 87 degrees on the 27th.
** 6th driest April on record since 1871 with 0.71 inches of
   precipitation.

May: None.

Top Ten Seasonal Records:
** 7th warmest spring on record since 1871 with a mean average
   temperature of 52.1 degrees.
** 3rd driest spring on record since 1871 with 3.75 inches of
   precipitation.


At Rockford, the average high temperature for the spring season was
62.5 degrees, which is 3.4 degrees above normal. The average low
temperature was 41.5 degrees, which is 2.8 degrees above normal.
The mean temperature for the season was 52.0 degrees, which is 3.1
degrees above normal.

A total of 5.51 inches of precipitation was recorded during this
past spring, which is 4.82 inches below normal. In addition, a
total of 2.0 inches of snow fell, which is 3.8 inches below
normal.

Records established or tied during the spring months:

March:
* Tied record daily maximum temperature of 68 degrees on the 9th.
* Record daily highest minimum temperature of 51 degrees on the 10th.
** 9th warmest March on record since 1905 with a mean average
   temperature of 42.8 degrees.

April:
* Tied record daily snowfall of a trace on the 20th.

May:
* Tied record daily maximum temperature of 88 degrees on the 1st.
* Tied record daily highest minimum temperature of 61 degrees on
  the 2nd.
* Record daily highest minimum temperature of 70 degrees on the 25th.

Top Ten Seasonal Records:
** Tied for 5th warmest spring on record since 1905 with a mean
   average temperature of 52.0 degrees.
** 7th driest spring on record since 1905 with 5.51 inches of
   precipitation.

$$

Latest Seasonal Climate Report:   Chicago   |   Rockford  

Lack of Severe Weather

Meteorological Spring 2021 featured an abnormal lack of severe weather, let alone thunderstorms. Here are some fast facts:

• The only day on which severe weather was reported in northern Illinois was April 29. Typically, our area sees 9 days of severe weather or flash flooding by June 1.
• No severe weather or flash flooding was reported during the entire month of May, which was the first time this has happened since 2002 and only the 14th time since 1950 (the year that National Weather Service storm report records date back to).
• Chicago O'Hare has only reported thunder two times so far this year. Normally, thunder is reported on about 45 days per year.
• NWS Chicago has issued 2 Severe Thunderstorm and 0 Tornado warnings so far this year, which is amongst the lowest totals across all 122 NWS forecast offices in the U.S..
• The majority of severe weather in 2021 has remained in the Southern and Central United States. 

What does this mean going forward? 

Typically, May, June, July, and August are the most active months for severe weather and flash flooding across the NWS Chicago forecast area.

A quiet spring does not always mean the rest of the year will be quiet. Similar years with a slow start to the severe weather season:

       2002: Two tornadoes after June 1

       1990: Five tornadoes after June 1, including the Plainfield F5 Tornado

       1978: Seven tornadoes after June 1, including three F2s

       1969: Four tornadoes after June 1, including an F2

       1968: One tornado after June 1

       1959: Eleven tornadoes after June 1, including three F2s

       1958: Ten tornadoes after June 1, including four F2s

       1950: One tornado after June 1

Bottom Line: Don't let your guard down. Thunderstorms will occur this summer, and some will likely be severe. A quiet spring does not mean we're out of the woods! 

Events

• March 10-11, 2021: Strong winds gust as high as 50 to 60 mph over the area

NWS Chicago Science and Past Events Page