Quarterly Climate Impacts 

and Outlook

Great Lakes Region

September 2017

#regionalclimateoutlooks

Great Lakes Region 

Quarterly Climate Impacts and Outlook

 - September 2017 - 

http://mrcc.isws.illinois.edu/pubs/pubsGreatLakes.jsp

www.ec.gc.ca/eau-water/default.asp?lang=En&n=F5329B03-1

Many locations in the Great Lakes basin received 

above-normal precipitation this summer, with some 

locations receiving record-breaking precipitation. For 

example, Avon and Watertown (NY) experienced their 

wettest summer since records began in 1896 and 1950, 

respectively. 

Bouts of heavy precipitation resulted in several flash 

flooding events across the basin, with notable events in 

all three months. One such event occurred from August 

28-29, when rainfall totals of 220 to 290 mm (8.7 to 11.4 

in) fell in Essex County, Ontario and resulted in significant 

flooding to roads and basements.

Wet conditions in the basin resulted in water levels of all 

the Great Lakes remaining well above average throughout 

the summer. Lake Ontario set new record-high monthly 

average water levels in June at 75.81 m (248.7 ft) and 

July at 75.69 m (248.3 ft), the highest since records began 

in 1918. Record high outflows were released from the 

Moses-Saunders Dam throughout the summer to provide 

relief to Lake Ontario shoreline interests. As a result, and despite the wet weather and continuing high inflows from Lake Erie, Lake Ontario water 

levels dropped 64 cm (25 in) from the start of June to the end of August, the 2nd largest drop during this three-month period on record. 

On July 20, an EF2 tornado touched down in Hamburg (NY), resulting in millions of dollars in damage (estimated) at the Erie County Fairgrounds, 

as well as significant home damage and power outages. The last time Erie County had an EF2 or stronger tornado was in 1987.

 Great Lakes Significant Events - for June - August 2017

Precipitation

Regional Climate Overview - for June - August 2017

Water level statistics based on 1918-2016.

Temperature

Summer precipitation was near or above 

average for all lake basins, with the overall 

basin receiving 110% of average. June was the 

wettest month this summer, with the overall 

basin receiving 135% of average precipitation. 

In July, all lake basins but Ontario saw near- or 

below-average precipitation, with the overall 

basin receiving 89% of average. The Erie and 

Ontario basins were slightly drier than average 

in August, while the Superior and MichiganHuron basins were wetter than average. The 

overall basin saw 105% of average precipitation 

in August. Precipitation normals based on 1981-2010.

June-August 2017 Precipitation: 

Percent of Normal (%)

Great Lakes Water Levels

Air temperature normals based on 1981-2010. 

Water temperature LTA based on 1995-2016.

Lake

End of August 2017 

Compared to:

Change since 

June 1st

Average Last Year 2017 Average

Superior +25 cm 

(+9.8 in)

+9 cm 

(+3.5 in)

+16 cm 

(+6.3 in)

+13 cm 

(+5.1 in)

MichiganHuron+44 cm 

(+17.3 in)

+16 cm 

(+6.3 in)

+11 cm 

(+4.3 in)

+1 cm 

(+0.4 in)

Erie +48 cm 

(+18.9 in)

+24 cm 

(+9.4 in)

-17 cm 

(-6.7 in)

-11 cm 

(-4.3 in)

Ontario +41 cm 

(+16.1 in)

+43 cm 

(+16.9 in)

-64 cm 

(-25.2 in)

-21 cm 

(-9.1 in)

August 2017 Air Temperature:

Departure from Normal

Air Temperature: Summer temperatures generally ranged from 2°C (3.6°F) 

below normal to near normal. The greatest temperature departures this 

summer were in August, when some areas were as much as 3°C (5.4°F) below 

normal. Portions of Minnesota and Michigan recorded 0°C (32°F) between 

August 24-25, which is more than a month ahead of the median first freeze 

dates for these areas (based on 1981-2010 normal). In July, temperatures 

ranged from 2°C (3.6°F) below normal to 2°C (3.6°F) above normal. June was 

up to 2°C (3.6°F) warmer than normal for a majority of the basin.

Water Temperature: Surface water temperatures on lakes Erie and Superior 

were cooler than the long-term average (LTA) by 0.5 to 2°C (0.9 to 3.6°F) for 

June through August while the other lakes were 0.5 to 1.5°C (0.9 to 2.7°F) 

higher than the LTA. In contrast, during the same period last year, all lakes 

were 1 to 3.5°C (1.8 to 6.3°F) higher than the LTA.

June-August 2017 Water 

Temperature: Departure from LTA
Regional Impacts - for June - August 2017

Regional Outlook - for October - December 2017 Great Lakes Region Partners

Environment and Climate Change Canada (ECCC)

www.ec.gc.ca

Agriculture and Agri-Food Canada

www.agr.gc.ca 

Midwestern Regional Climate Center

mrcc.isws.illinois.edu

Northeast Regional Climate Center

www.nrcc.cornell.edu

Great Lakes Region State Climatologists

www.stateclimate.org

National Oceanic and Atmospheric Administration

www.noaa.gov

National Centers for Environmental Information

www.ncei.noaa.gov

Great Lakes Environmental Research Laboratory

www.glerl.noaa.gov

NOAA Great Lakes Sea Grant Network 

www.seagrant.noaa.gov

North Central River Forecast Center

www.crh.noaa.gov/ncrfc

Ohio River Forecast Center

www.weather.gov/ohrfc 

Climate Prediction Center

www.cpc.noaa.gov

Office for Coastal Management

http://coast.noaa.gov/

Great Lakes Integrated Sciences & Assessments

www.glisa.umich.edu

US Army Corps of Engineers, Detroit District

www.lre.usace.army.mil

National Integrated Drought Information System 

www.drought.gov

USDA Midwest Climate Hub

https://www.climatehubs.oce.usda.gov/midwest

Contact for NOAA: 

Molly Woloszyn: mollyw@illinois.edu

Samantha Borisoff: samantha.borisoff@cornell.edu

Contact for ECCC: ec.enviroinfo.ec@canada.ca

Archive: goo.gl/3WA5QZ 

Contact Information

#regionalclimateoutlooks

Great Lakes Region 

Quarterly Climate Impacts and Outlook

 - September 2017 - 

http://mrcc.isws.illinois.edu/pubs/pubsGreatLakes.jsp

www.ec.gc.ca/eau-water/default.asp?lang=En&n=F5329B03-1

Outlook

The Climate Prediction Center (CPC) and Environment and Climate Change Canada (ECCC) are 

forecasting a greater chance for above-normal temperatures and equal chances for above-, 

near-, or below-normal precipitation across 

the Great Lakes basin for October-December.

However, NOAA now says there is an increasing 

chance (55-60%) of La Niña during fall and winter 

2017-18. For the Great Lakes basin, La Niña could 

mean wetter and cooler conditions in DecemberFebruary. Current outlooks can be found through 

CPC and ECCC. 

Potential Impacts

Despite the outlook for warmer-than-normal 

temperatures in October-December, the delayed 

planting, unseasonably cool late-summer temperatures, and wetter soils have led to concerns 

that plants will not mature before the first killing frost. In Ontario, crop development was 

estimated to be about one week behind normal at the end of the August. The first fall 0°C (32°F) 

freeze typically occurs in late September and early- to mid-October across the Great Lakes basin.

Agriculture The weather conditions this summer 

caused significant issues for farmers 

across the basin. A farm near Toronto lost 

hundreds of acres after a late-June heavy 

rainfall event, resulting in an estimated 

$2.5 million in damages. The wetter 

and cooler conditions have resulted in 

delayed planting and crop development, 

unseeded acres, reduced field access, 

and loss of crops due to flooded fields. As 

a result, reduced crop yields and quality 

are anticipated. 

Water Quality

Several beaches and lake access points 

were closed temporarily at various points 

throughout the summer due to positive 

tests for harmful blue-green algae. One 

lake that tested positive was Cayuga Lake, 

which is a popular tourist destination in 

the Finger Lakes Region of New York.

Lake Ontario High Water Level Impacts

Lake Ontario water levels have declined during summer but still 

remained well above average and continued to impact communities 

and businesses within the Lake Ontario-St. Lawrence River system 

with widespread flooding and erosion issues. Tourism suffered due to 

extensive flooding and high water damage to shoreline communities, 

beaches, and parks, which negatively impacted local businesses. High 

water damage along the waterfront in Ogdensburg (NY) is estimated 

to cost $1.5 million to repair and it could be well into next year before 

public access is allowed. The Toronto Islands were closed to the public 

until July 31 due to flooding, costing the City of Toronto an estimated $8 

million in revenue. While higher water levels allowed some commercial 

ships to carry heavier loads, the high flows this year increased velocities 

and cross currents in the St. Lawrence River considerably. This presented 

difficult conditions for mariners and required significant mitigation 

measures for safe navigation, all of which substantially slowed cargo 

shipments. The measures are provided in notices from the St. Lawrence 

Seaway Management Corporation. 

Societal

Several flash flooding events this 

summer caused damage and disruption 

to many areas in the basin. Portions of 

central Michigan received up to 178 

mm (7 in) of rainfall from June 22-23. 

As a result, more than 5 million gallons

of partially-treated wastewater was 

discharged into the Tittabawassee River 

and in the hardest hit counties, public and 

private property flood damage is estimated 

at over $100 million. Portions of Ohio and New York experienced flash 

flooding from July 13-14. The Blanchard River near Findlay (OH) had its 

fifth highest crest on record.

Water Levels

Temperature & Precipitation

Potential range for water levels for Oct-Dec 2017 compared to the long-term average (1918-2016). 

Flooded farm north of Toronto in late 

June (Dorsey Farms).

All of the Great Lakes typically begin or continue 

their seasonal decline at this time of the year, 

as lake evaporation rates are at their highest. As 

cold, dry air passes over a lake, it is warmed by the 

lake’s water surface and picks up water vapor as a 

result. With more water leaving the basin - in the 

form of evaporation - than entering, water levels 

can continue to decline. This year, water levels are 

still expected to remain above average for all the 

Great Lakes unless exceedingly dry conditions are 

experienced.

Typical impacts of La Niña on U.S. winter temperature 

and precipitation (NOAA Climate.gov).

Flooding in Findlay, OH

(City of Findlay, Brian Thomas).

Harmful algal bloom in western Lake 

Erie on 8/14/17 (NOAA GLERL).