Because of Milwaukee's proximity to Lake Michigan, a convection current forms around mid-afternoon in light wind, resulting in the so-called "lake breeze" – a smaller scale version of the more common sea breeze. The lake breeze is most common between the months of March and July. This onshore flow causes cooler temperatures to move inland usually 5 to 15 miles (8 to 24 km), with much warmer conditions persisting further inland. Because Milwaukee's official climate site, Milwaukee Mitchell International Airport, is only 3 miles (4.8 km) from the lake, seasonal temperature variations are less extreme than in many other locations of the Milwaukee metropolitan area.