CHICAGO (CBS) — As if the unusually cool weather weren’t reason enough to avoid Lake Michigan on Tuesday, swimming was banned at several lakefront beaches, due to dangerous rip currents. Swimmers were being warned of high bacteria levels at a handful of other beaches.

According to the Chicago Park District, swimming was banned at 14 beaches – Columbia, Farco, Hartigan, Howard, Juneway, Lane, Leone, Loyola, Marion Mahoney Griffin, North Avenue, North Shore, Osterman, Rogers, and Tobey Prinz beaches – on Tuesday due to “hazardous surf.”

According to the National Weather Service, high waves and dangerous swimming conditions are expected along much of the lakefront on Tuesday, with waves of 4 to 7 feet possible, and strong rip currents and structural currents expected.

“Rip currents are powerful channels of water flowing quickly away from shore, which occur most often at low spots or breaks in sandbars. Structural currents form along piers where longshore currents and wave action flow into the structure. Rip currents and structural currents can sweep you into deeper water,” the service said in a beach hazard statement.

The Park District said another six beaches – 31st Street, 63rd Street, Calumet, Montrose, Rainbow, and South Shore beaches – were under swim advisories, due to water quality issues caused by high bacteria levels, usually caused by runoff from storms.

The temperature in Chicago was only about 61 degrees late Monday morning – more than 20 degrees below the normal high temperature for early July – and the water temperature in Lake Michigan was only 64 degrees, hardly ideal for swimming, even in calm and clean conditions.