MIDWEST CLIMATE: EL NIÑO

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HISTORICAL EL NIÑO EVENTS

Strong El Niño Events

It has been 17 years since a strong El Niño has occurred and captured the public eye.  While many have pointed to the 1997-1998 El Niño for comparison and guidance for the 2015-2016 event, there were other strong El Niño events that can be analyzed for comparisons. 

Year Start ONI value

Starting Season

Peak ONI value

Peak Season

1957-58 0.6 MAR-MAY 1.7 DEC-FEB
1965-66 0.7 MAY-JUL 1.8 OCT-DEC
1972-73 0.6 APR-JUN 2.0 OCT-DEC
1982-83 0.5 MAR-MAY 2.1 OCT-FEB
1991-92 0.6 MAY-JUL 1.6 DEC-FEB
1997-98 0.6 APR-JUN 2.3 OCT-JAN
2015-16

0.5

FEB-APR

?

?

Seven El Niño events that have reached an Oceanic Niño Index (ONI) value of 1.5 during the ONI’s current period of record of 1950-present.  Reaching that ONI value is commonly considered to be the threshold for a strong El Niño event.  However, one of these events, the 1987-88 event, is not usually used for comparisons to other strong El Niño events.  In 1987-88, the peak ONI value of 1.6 was reached during the late summer to early fall.  When the winter of 1987-88 emerged, the time of year where an El Niño has the most effect, the El Niño event was decaying into a moderate to weak El Niño.   For this reason, 1987-88 will not be included in our comparisons of strong El Niño events.  The six strong El Niño events shown in the comparisons below are from the 1957-58, 1965-66, 1972-73, 1982-83, 1991-92 and 1997-98 winter seasons.

Values for ONI peaked in the late fall to early winter during 5 of these El Niño events, with a late winter peak during the 1957-58 and 1991-92 events.  Only the 1997-98 event followed a smooth parabolic curve in ONI values while the other years grew and decayed in a more variable manner. The 1972-73 El Niño peaked in October-December then rapidly declined, while the 1965-66 El Niño peaked at the same time but declined more slowly.

ONI values for six strong El Niño events compared to the current El Niño (red)
ONI values for six strong El Niño events compared to the current El Niño (red).

 

Midwest Winters During Strong El Niño Events

When looking at the average temperature pattern of the six strong El Niño events in the Midwest, temperatures were well above normal, with Minnesota experiencing the most above normal temperatures.  Precipitation was near normal in the western portions of the region while below normal precipitation fell across the northern Ohio Valley.  Examining these events individually, however, tells a different story.

Composite image of temperature during six strong El Niño winters   Composite image of precipitation during six strong El Niño winters
Composite images of temperature (left) and daily precipitation (right) departures during six strong El Niño winters. 
Image Credit: NOAA Earth System Research Laboratory. http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/printpage.pl

 


Temperature (°F) ranks and departures from the 1981-2010 normals during six strong El Niño winters for the 9-state Midwest region. Ranks are from warmest to coldest. Ranks with a "T" represent ties.  Data are based on the nClimDiv dataset from NCEI with a period of record from 1895-2015.

 

The strong El Niño winters of 1957-58, 1965-66 and 1972-73 had below normal temperatures for the Midwest as a whole and rank close to the middle of the pack in the 120 years on record.  However, the most recent three strong El Niño winters in 1982-83, 1991-92 and 1997-98 ranked in the top six warmest winters on record for the Midwest.  The 1997-98 El Niño winter is tied with 2001-02 as the warmest winter on record for the region. Minnesota also recorded its warmest winter on record during the 1997-98 season.

 

Winter temperature departure from Normal
Winter temperature departure from normal (1981-2010 normal) across the Midwest during six strong El Niño winters.

Precipitation ranks and departures
Precipitation (inches) ranks and departures from the 1981-2010 normals during six strong El Niño winters for the 9-state Midwest region.  Ranks are from wettest to driest.  Ranks with "T" represent ties.  Data are based on the nClimDiv dataset from NCEI with a period of record from 1895-2015.

 

Precipitation was near normal for three of the six strong El Niño winters in the Midwest. The winter of 1982-83 was the only event that received more than ten percent above normal.  Both the 1957-58 and 1991-92 events were more than ten percent below normal.  Only 1982-83 (1957-58) ranked in the top 30 wettest (driest) winters on record.

 

Winter precipitation percentage of normal
Winter precipitation percentage of normal (1981-2010 normal) across the Midwest during six strong El Niño winters.

Less than average snowfall was generally found during strong El Niño winters in the Midwest.  The Upper Midwest received above normal snow once during the 1972-73 event. Above normal snowfall only occurred in Missouri during the 1957-58 event.  The 1965-66 and 1997-98 winters brought over twice the normal amount of snow in Kentucky, while the state received very little snow in 1972-73, 1982-83 and 1991-92.   During the 1997-98 El Niño, most of the snow in the region fell outside of the typical winter months of December, January and February.  Read more on the 1997-98 El Niño event in the Midwest from the MRCC report..

Winter snowfall percentage of mean
Winter snowfall percentage of 1981-2010 mean across the Midwest during six strong El Niño winters.

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Strong El Niño State Comparison Maps

Click a map to enlarge.


State
Temperature:
Departure from Normal (1981-2010)
Precipitation:
Percent of Normal (1981-2010)
Snowfall:
Percent of Normal (1981-2010)
Temperature & Precipitation
Rankings
Illinois Enlarge: IL Temp Departure from Normal Enlarge: IL Precip Percent of Normal Enlarge: IL Snow Percent of Normal Enlarge: IL Temp & Precip Rankings
Indiana Enlarge: IN Temp Departure from Normal Enlarge: IN Precip Percent of Normal Enlarge: IN Snow Percent of Normal Enlarge: IN Temp & Precip Rankings
Iowa Enlarge: IA Temp Departure from Normal Enlarge: IA Precip Percent of Normal Enlarge: IA Snow Percent of Normal Enlarge: IA Temp & Precip Rankings
Kentucky Enlarge: KY Temp Departure from Normal Enlarge: KY Precip Percent of Normal Enlarge: KY Snow Percent of Normal Enlarge: KY Temp & Precip Rankings
Michigan Enlarge: MI Temp Departure from Normal Enlarge: MI Precip Percent of Normal Enlarge: MI Snow Percent of Normal Enlarge: MI Temp & Precip Rankings
Minnesota Enlarge: MN Temp Departure from Normal Enlarge: MN Precip Percent of Normal Enlarge: MN Snow Percent of Normal Enlarge: MN Temp & Precip Rankings
Missouri Enlarge: MO Temp Departure from Normal Enlarge: MO Precip Percent of Normal Enlarge: MO Snow Percent of Normal Enlarge: MO Temp & Precip Rankings
Ohio Enlarge: OH Temp Departure from Normal Enlarge: OH Precip Percent of Normal Enlarge: OH Snow Percent of Normal Enlarge: OH Temp & Precip Rankings
Wisconsin Enlarge: WI Temp Departure from Normal Enlarge: WI Precip Percent of Normal Enlarge: WI Snow Percent of Normal Enlarge: WI Temp & Precip Rankings

Most Recent El Niño Event:  2009-2010

The last El Niño event occurred in 2009-2010.  This El Niño had an ONI value of 1.3 and was considered a moderate event.  The 2009-2010 winter was much colder than normal across the region.  Only Michigan recorded above normal temperatures for the December through February period while Kentucky, Iowa and Missouri had temperatures four or more degrees below normal.  These three states ranked in the top 20 coldest winters on record.  The Midwest as a whole was 2.8°F below normal.

2009-2010 El Niño - Peak ONI 1.3  Dec-Feb precip rankings and departures for the 2009-2010 El NiÑo in the Midwest
Temperature (left, °F) and Precipitation (inches) ranks and departures from the 1981-2010 normals for December-January 2009-2010.  Ranks are from
warmest to coldest and wettest to driest, respectively.  Ranks with "T" represent ties.  Data are based on the nClimDiv 
dataset from NCEI 
with a period of record from 1895-2015

Percent of normal precipitation, percent of normal snowfall, and departure from normal
Departure from normal temperature (left), percent of normal precipitation (middle), and percent of normal snowfall (right) in the Midwest
for the 2009-2010 moderate El Niño event.

Snowfall was also prevalent across the region.  Only a few areas around the Great Lakes recorded below average snowfall for the winter months.  Most of Iowa, southwest Minnesota and northwest Missouri had more than double the average amount of snow for the winter. Most of Ohio had more than one and half times the average amount.  However, only the Upper Midwest had above normal precipitation for the winter.

Why don’t all El Niño events have similar patterns?

Not all El Niño events are created equal.  Find out why on our Diversity of El Niño page.

 
More Historical El Niño Reports & Links

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