Snow mold is a lawn disease indicating that the grass is suffering from a fungal infection. It occurs, usually, in cold and humid weather. The term “snow” is somehow misleading in this context, because this disease also appears frequently in the absence of snow; it only need humid conditions and a temperature between 0 and 8 °C.
Therefore snow mold will not appear exclusively in winter, but at any time of the year with rather cold weather or after temperature fluctuations. This fungal infection will not spread when the temperature is exceeding 20 °C and it occurs frequently in combination with other diseases that develop in winter.
If it is affected by snow mold, the lawn will suffer on a smaller scale first; you will notice small circular areas of plants turning gray-ish and looking saturated of water, and, in the end, more areas like this will eventually join. They will have a brown color, with gray-white edges.
As temperatures rise, snow mold stops growing, and the stains on the lawn begin to disappear automatically, as grass regenerates. To speed up the recovery process, you can use an aerator on the affected areas and plant some new lawn seeds as well as apply Revive products to have a lush green lawn in no time.