Lake Ontario average July sea temperature

Max: 25.6°C / 74.7°F

Avg: 21.4°C / 70.5°F

Min: 17.2°C / 66.3°F

These figures are calculated from several years of recorded data and are the maximum, minimum and average temperatures of all the recorded years

Average July sea temperatures

Monthly Lake Ontario water temperature chart

The bar chart below shows the average monthly sea temperatures at Lake Ontario over the year.

Average monthly sea temperatures in Lake Ontario
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
°C 3.4 2.8 2.2 3.5 5.5 14.9 21.4 22.7 20.3 14.2 9.2 5.4
°F 38.1 37 36 38.3 41.9 58.8 70.5 72.9 68.5 57.6 48.6 41.7

Monthly average max / min water temperatures

The graph below shows the range of monthly water temperatures over several years.

Maximum and minimum monthly sea temperatures in Lake Ontario
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Min °C 2.2 1.2 0.3 1 2.7 7.8 17.2 20.6 17.4 9.8 7.3 3.1
Max °C 4.7 4.4 4.2 6.1 8.3 22 25.6 24.8 23.2 18.6 11.1 7.7
Min °F 36.9 35.4 34.1 35.8 39.1 51.7 66.3 70.8 65.6 53.2 46.7 39.4
Max °F 39.4 38.6 38 40.9 44.7 65.9 74.7 75 71.4 62 50.5 44

Lake Ontario weather & temperature averages »