Lake Breeze defined: why it’s always cooler by the lake shore

Weather Glossary

ROCHESTER, NY (WROC) – Ever wonder why the lakeshore is often so much cooler in the spring and summer than places farther from the lake? Our beloved Lake Ontario is with no surprise a huge influencer of our local weather and climate, and the phenomenon you can thank for that is known as a lake breeze.

A lake breeze can be defined as a local change in wind that blows from water to land (typically from a lake or ocean) caused by temperature differences between the land and water. Lake breezes play a large role in our weather here in Rochester as they can have a dramatic effect on temperatures in our area.

This small scale breeze often occurs during late spring, summer, and early fall where our land temperature begin to surpass the cooler water temperature. It also helps to have large scale, calm conditions such as a high pressure system overhead where large scale winds won’t interfere with the smaller scale winds. 

Here’s how it works: 

During a warm day the sun will heat up the land faster than the water due its high specific heat. Specific heat is defined as the amount of heat or energy required to raise 1 gram of substance 1 degree Celsius, or in this case, water. This means that it takes water much longer to respond to changes in temperature than the land does, making it easier to keep cool after a long winter while the land next to it warms up with the warming seasons.

Heating from the sun during the day causes the land to warm and air to rise since warm air is less dense than cold air. The rising air at the surface creates an area of low pressure since that air is forced up creating higher pressure aloft. High pressure always flows towards lower pressure, so naturally the cool, sinking air creating higher pressure over the lake surface will want to flow onto the warm land. This flow of air from high to low is your lake breeze! 

Image courtesy of the NWS.

You don’t always need large temperature differences for a lake breeze to get going, but the larger the difference the stronger the lake breeze can be. 

The deeper the lake the more effective a lake breeze is. If the lake is too shallow it is more likely to heat up faster than a deeper lake would. This causes the deeper lake to heat up more slowly and therefore stay cool enough to create the right environment for lake breeze formation.

Take a look at these current temperatures from during the day:

Temperatures from this afternoon greatly varied from the lake shore to inland. Nearly a 14 degree temperature difference stood from Sodus to Penn Yan. Even Rochester was sitting 8 degrees higher than Sodus sitting just 5 miles away from the shore. This really shows just how local lake breezes can be.

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