The temperature at which ponds and lakes freeze has always been a question, and not an easy one to answer. It is dependent upon numerous many factors, all of which must be known and considered. The temperature at which pure water freezes is 0 Celsius or 32 Fahrenheit and is the same everywhere on Earth. Unfortunately, ponds and lakes are not pure water or the same anywhere!
One is how does one define “freeze”. Does this mean at what temperature do bodies of water stay froze or they first start to freeze, with ice forming around the edges? Maybe it means at what temperature will there be ice all the way across the surface. Many Canadians and northern Europeans would claim the lake wasn’t froze unless you can drive a truck out, chop a hole through several feet and then start ice fishing. Freeze in regards to a lake needs to be defined!
Then there is the location and size of the pond or lake, as well as water turnover rate. A small stagnant pond will freeze much faster than a large, vibrant lake. The water becomes a uniform temperature much faster. A deep pond or lake has more swelling and upheaval, and until all the water reaches 4 degrees Celsius, it keeps shifting and the top layer will not start to freeze. The larger the body of water the longer that takes and the colder it must get!
Mineral content can also play an important part in freezing of any body of water. A clear pure lake will freeze at a much warmer temperature than a small, brackish filled pond. The same applies to clay type of soils verse a pond with a rock bottom. Dissolved minerals, and they are found in all bodies of water, effect freezing temperatures. Pollutants and runoff from roads can change mineral content, and thus the freezing point can change each year, especially if it is a small pond!
How full is the lake or pond with life and what type? All plants, and animals, have metabolism and effect the environment in which they live. They all produce excess heat and waste products. This heat and waste products will keep the pond or lake from freezing! The more biological activity, the colder the temperatures required to freeze it.
At what temperatures will ponds or lake freeze in your area? That is a good question, and one I cannot answer!