Quarterly Climate Impacts 

and Outlook

Great Lakes Region

September 2015

#regionalclimateoutlooks

Great Lakes Region 

Quarterly Climate Impacts and Outlook

 - September 2015 - 

www.drought.gov/drought/content/resources/reports

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

 Great Lakes Significant Events - for June - August 2015

Precipitation

Regional Climate Overview - for June - August 2015

Even though the basin-wide summer averages for 

temperature and precipitation were near normal, the 

Great Lakes basin experienced a range of weather during 

summer 2015. From a wet and cool June to a drier July 

and sporadic waves of hot and humid weather in July and 

August. June 2015 was the wettest June on record since 

1895 for Illinois, Indiana, and Ohio, the 2nd wettest for 

Pennsylvania, and 3rd wettest for New York. In Ontario, 

Windsor measured its wettest June on record, while it 

was the second wettest June for Toronto and Kingston. 

Water supplies in June were record high for the Lake Erie 

basin and near record high for the Lake Ontario basin. As 

a result, lakes Erie and Ontario experienced record water 

level rises of 28 cm (11 in) and 33 cm (13 in), respectively, 

in June. This is significant since it is possible for both 

lakes to begin their seasonal declines in June. Overall, 

the generally wetter-than-normal conditions, particularly 

in June, resulted in the water levels on all Great Lakes 

ending the summer above average, higher than last year 

and the highest since the 1990s. 

A strong storm system moved over the Great Lakes basin on August 2, causing a barrage of severe weather including hail, high winds, heavy 

rainfall, and tornadoes. High winds blew across the Great Lakes, including numerous gale force wind gusts over 61 kmph (38 mph) and also 

some storm force wind gusts over 87 kmph (54 mph). Despite the high winds, there were no accompanying high waves or seiches on the 

lakes. This event also produced the largest outbreak of severe storms in Ontario this summer, including four tornadoes, two of which were 

EF2 tornadoes in the small southwestern Ontario communities of Teviotdale and Lebanon. On the U.S. side, there were several large hail 

reports in Wisconsin, Michigan, Minnesota, and Illinois, one of which was for softball-sized hail (10.8 cm, 4.25 in) in Clear Lake, Michigan. 

Air Temperature

June temperatures ranged from near normal to 3°C (5.4°F) below normal. In July, most of 

the region experienced temperatures ranging from near normal to 2°C (3.6°F) below normal. 

However, the western Lake Superior basin was warmer. 

August temperatures ranged from 2°C (3.6°F) below normal 

on the southern side of the basin to 2°C (3.6°F) above 

normal on the northern side of the basin. Overall, summer 

temperatures ranged from near normal to 2°C (3.6°F) 

below normal. Summer 2015 is the 7th season in a row 

with below normal temperatures over the basin.

Water level statistics based on 1918-2014. 

June-Aug 2015 Air Temp: 

Departure from Normal

Temperature

Great Lakes 

Water Levels

Despite a dry July, the Superior and 

Michigan-Huron basins experienced normal 

to wet conditions in June and August. As a 

result, Lake Superior ended the quarter 16 

cm (6.3 in) above average and the highest 

for this time of year since 1996 and Lake 

Michigan-Huron finished the quarter 18 cm 

(7.1 in) above 

average and 

the highest 

this time of 

year since 

1998. With 

the Lake Erie 

basin wetterthan-normal in 

June and July but dry in August, Lake Erie 

water levels at the end of August were 33 

cm (13 in) above average, 23 cm (9.1 in) 

higher than last year and the highest since 

1998. The Lake Ontario basin was wetterthan-normal this summer, which led to Lake 

Ontario ending the quarter 19 cm (7.5 in) 

above average and the highest this time of 

year since 1992.

The Great Lakes basin received 128% of average June 

precipitation. The Erie and Ontario basins were very wet 

at 194% and 180% of average, respectively. All lake basins 

had near to below average precipitation in July, with the 

overall basin seeing 81% of average. In August, all lake 

basins except Erie had near-average precipitation, with 

the entire basin seeing 103% of average. The overall basin 

received 104% of normal summer precipitation, with near 

to above normal precipitation in the individual lake basins.

June 2015 shown to display greatest anomalies. 

Precip normals based on 1981-2010.

Air temperature normals based on 1981-2010.

 June 2015 Precip: 

Percent of Normal (%)

Water Temperature

Great Lakes water temperatures during summer were 

0.5°C to 4.7°C (0.9°F to 8.5°F) below the long term average 

(1995-2014), with the exception of a few areas.

Lake Huron on 6/25/2015 (Photo: 

Michigan Sea Grant via Flickr)
Regional Impacts - for June - August 2015

Regional Outlook - for October - December 2015 Great Lakes Region Partners

Environment Canada

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 Operational Hydrologic Remote Sensing Center

www.nohrsc.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

#regionalclimateoutlooks

Contact for NOAA: 

Molly Woloszyn: mollyw@illinois.edu

Samantha Borisoff: samantha.borisoff@cornell.edu

Contact for Environment Canada: 

greatlakes-grandslacs@ec.gc.ca

enviroinfo@ec.gc.ca

Great Lakes Region 

Quarterly Climate Impacts and Outlook

 - September 2015 - 

www.drought.gov/drought/content/resources/reports

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

Contact Information

Environment Canada (EC) and the Climate Prediction Center (CPC) are forecasting a significant 

chance for above normal temperatures across the Great Lakes basin for October-December 

2015. The CPC is forecasting greater chances for below normal precipitation across much of 

the U.S. Great Lakes basin except for western Lake Superior, while EC indicates there is no clear 

signal at this time whether precipitation will be below, near, or above normal for OctoberDecember. 

Since spring 2015, the equatorial Pacific Ocean 

has been experiencing warmer than average sea 

surface temperatures, meaning that El Niño is 

occurring. The seasonal forecasts for OctoberDecember is reflecting the fact that El Niño has a 

greater than 95% chance of continuing through 

winter 2015-16, according to the CPC. Based 

on previous years, El Niño winters tend to be 

warmer than normal in the basin, with drier 

than normal conditions in the eastern basin, less 

snow than usual, and reduced ice cover on the lakes. 

The current outlooks can be found through the Climate 

Prediction Center and Environment Canada.

High Water Level Impacts

Above average water levels on the 

Great Lakes can bring a mix of negative 

and positive impacts. The higher water 

levels reduced the size of beaches 

around the Great Lakes, increased the 

risk of shoreline flooding and erosion, 

and encroached on the property of 

beachfront owners. On the other hand, 

the higher water levels may benefit the 

shipping industry, recreational boating, and hydropower generation.

Water Quality

As predicted, the Lake Erie harmful algal bloom is large this year, 

rivaling the size of the largest bloom in 2011. Heavy rains in June 

increased river flow and as a result, the 

Lake Erie bloom developed farther east 

than it typically does, closer to the Lake 

Erie islands. By August, the bloom was 

predominantly in the western Lake Erie 

basin, but extended into the central basin. 

The algal bloom in Lake Erie was confirmed 

to be toxic cyanobacteria, resulting in 

beach advisories this summer. Fortunately, 

as of September, the toxins from the bloom 

have not impacted drinking water supplies like last year. Lake St. Clair 

(located in between Lake Huron and Lake Erie) also experienced a 

large harmful algal bloom this summer.

Agriculture

The wet conditions in June resulted in 

limited ability to do fieldwork in June 

and early July. The June rain also flooded 

many fields in the areas surrounding the 

Great Lakes basin, which led to delayed 

planting or in some cases, the inability 

to plant in some locations this year. In 

addition, persistent wet conditions led 

to earlier than normal crop disease development. After the wet start 

to the summer, the Great Lakes basin did experience more favorable 

conditions for crop growth in July and August.

Storm Damage

Damage from the August 2 storm included over 50,000 customers 

without power in southwestern Ontario and a number of damaged 

trees, homes, and downed power lines. On July 13, a microburst 

associated with a severe thunderstorm caused significant damage 

to docks and boats at a marina near Morrisburg in eastern Ontario. 

Heavy rainfall associated with this storm also created flooding issues 

along the south shore of Lake Ontario and in Ohio. 

Lake Level Outlook

During autumn months, water levels are typically 

in their seasonal decline as over-lake evaporation 

increases and water supplies generally decrease. 

Current projections from October to December show 

above-average water levels for lakes Superior, MichiganHuron and Erie unless exceedingly dry conditions are 

experienced. Lake Ontario is projected to be near 

average this fall unless exceedingly wet or dry conditions 

are experienced. Potential range for water levels for Oct-Dec 

2015 compared to the long-term average. 

Temperature & Precipitation Outlook

A flooded field in Illinois 

(Photo: Jim Angel)

Long-term average: 1918-2014

High water on Lake Erie on 

7/9/2015 (Photo: Ohio Sea Grant)

Algal bloom on Lake St. Clair on 

7/28/2015 (Photo: NASA)

The typical pattern in the winter during El 

Niño events. The polar jet stream tends 

to stay further north, while the Pacific jet 

stream remains across the southern U.S. 

(Graphic: NOAA)