Quarterly Climate Impacts 

and Outlook

Great Lakes Region

September 2018

Great Lakes Significant Events – for June - August 2018 

The Great Lakes region experienced extreme 

heat and rainfall events in the summer of 

2018. In late June and early July, several 

days of high temperatures and humidity 

made it feel like 38°C (100°F) with some 

areas reaching as high as 43°C (110°F). This 

prompted the issuance of Excessive Heat 

Warnings in the eastern portion of the basin. 

The lack of relief from the excessive heat led 

to two heat-related deaths in New York.

Several heavy rain events in July and August in 

the eastern half of the basin caused flooding 

that resulted in road damage, overflown 

streams, and several water rescues. On 

August 7, more than 64 mm (2.5 in) of rain 

fell in only two hours in the Toronto, ON 

area which led to flooded roads, power outages, and subway closures. Several downtown locations saw water pouring 

through ceilings and hallways, and two people had to be rescued from an elevator when rising waters trapped them.

The summer concluded with a severe weather outbreak in areas of the basin. The event on August 28 resulted in 19 

confirmed tornadoes across southeastern Wisconsin and an additional four confirmed tornadoes in northern Michigan. 

One tornado in Wisconsin was confirmed as an EF2, while all others were rated as EF0 or EF1.

Regional Climate Overview – for June - August 2018

Precipitation and Temperature Summer 2018 Temperature

Departure from Normal

June temperatures ranged from 2°C 

(4°F) below normal to 2°C (4°F) above 

normal. Both July and August had 

temperatures that were near normal to 

3°C (5°F) above normal. Many Canadian 

locations as well as Erie, PA and Buffalo, 

NY experienced a top 10 warmest 

August on record. Summer overall was 

similar to the last two months with 

temperatures that were near normal to 

3°C (5°F) above normal.

June precipitation ranged from half 

of normal in the Huron basin to near 

normal in the Superior and Erie basins. 

July precipitation ranged from 66% of 

normal in the Huron basin to 93% of 

normal in the Ontario basin. In August, 

all basins with the exception of Superior 

were 112% to 146% of normal. Superior 

reached only 88% of normal. For the 

summer, the U.S. portion of the basin 

had above normal precipitation while 

the Canadian side was below normal.

Great Lakes Water Levels

All of the Great Lakes ended August 

above average levels for this time of 

year, but all were also at or below 

their levels seen at the same time in 

2017, generally due to drier supply 

conditions and above average 

outflows this quarter compared to the 

same time last year. The level changes 

on Lake Superior and Michigan-Huron 

over the quarter were near average. 

The decrease in levels on Lake Erie 

and Ontario were above average.

Contact: Jonathan Weaver (jw1067@illinois.edu)

Normals based on 1981-2010.

Summer 2018 Precipitation

Percent of Normal

Lake

End of Aug. 2018 

Compared to:

Change since 

June 1st

Average 2017 2018 Average

Sup. +12 cm 

+4.7 in

-13 cm 

-5.1 in

+12 cm 

+4.7 in

+13 cm 

+5.1 in

Mich.-

Huron

+43 cm 

+16.9 in

0 cm

0 in

-1 cm 

-0.4 in

+2 cm 

+0.8 in

Erie +45 cm 

+17.7 in

-2 cm 

-0.8 in

-23 cm 

-9.1 in

-11 cm 

-4.3 in

Ont. +1 cm 

+0.4 in

-40 cm 

-15.7 in

-43 cm 

-16.9 in

-24 cm 

-9.4 in

Great Lakes Region Quarterly Climate Impacts and Outlook| September 2018 

https://www.drought.gov/drought/resources/reports
Regional Impacts – for June - August 2018

Agriculture around the Great Lakes experienced quick development during the early summer months as a result of 

above-normal temperatures. However, dry conditions began to develop and intensify through mid-to-late summer, 

primarily in eastern portions of the basin, resulting in increased stress on crops and livestock. Recent rainfall improved 

conditions, but some long-term precipitation deficits and concerns with livestock feed supplies remain around Lakes 

Huron and Erie. Some areas, like the Niagara region, were so dry that some crops never emerged in the first place.

Health and safety of many inhabitants of the Great Lakes basin were threatened by events such as forest fires, heat 

waves, harmful algal blooms, and flooding. Forest fires in central Ontario created an air quality hazard for residents 

of nearby communities. Abnormally high temperatures and humidity in early July led to heat-related health risks for 

many in the eastern portion of the basin. Excessive rainfall risked the safety of many across the basin, forcing several 

communities to evacuate while other rural areas, such as some in the upper peninsula of Michigan, were isolated due to 

widespread road closures.

Recreation over the summer has resulted in many deaths. Through Labor Day weekend, 72 deaths, including several 

drownings primarily in Lake Michigan and Lake Erie, occurred as a result of strong currents and rapidly changing wind 

conditions. Since 2010, 99% of the 643 people who have drowned in the Great Lakes were not wearing life jackets.

Escape method for rip currents

Regional Outlook – for October - December 2018

Temperature and Precipitation

Great Lakes Water Levels

Both American and Canadian forecasters predict above-normal temperatures for most of the Great Lakes basin in the 

October through December timeframe. At the same time, precipitation has been predicted to have an equal chance of 

being above, near, or below normal for the entire basin.

Forecasters have placed an El Niño watch into effect due to an increased likelihood (50-55%) of El Niño conditions 

developing over the next several months. A typical El Niño pattern results in a more northerly positioned jet stream. This 

can typically be associated with drier and warmer conditions, particularly during the winter months. Although colder and 

wetter conditions can occur, they are often less frequent and shorter in length during El Niño phases.

Partners

Contact: Jonathan Weaver (jw1067@illinois.edu) Great Lakes Region Quarterly Climate Impacts and Outlook| September 2018 

https://www.drought.gov/drought/resources/reports

Midwestern Regional Climate Center

Environment and Climate Change Canada

Agriculture and Agri-Food Canada

Northeast Regional Climate Center

Great Lakes Region State Climatologists

NOAA

 NCEI

 GLERL

 Great Lakes Sea Grant Network

 North Central River Forecast Center

 Ohio River Forecast Center

 CPC

 Office for Coastal Management

GLISA

US Army Corps of Engineers, Detroit District

NIDIS

USDA Midwest Climate Hub

All of the Great Lake levels are expected to be in their seasonal fall declines 

over the fourth quarter, assuming average water supply conditions. Lakes 

Superior, Michigan-Huron and Erie levels are likely to stay above average, even 

if very dry conditions are encountered.

Corn suffering from drought conditions Washed out road from flooding