It's getting hot in the kitchen!
With the arrival of summertime, lots of fresh seasonal produce becomes available and “canning season” really heats up. Unfortunately, so does your garage, attic, and maybe even your kitchen.
Storing canned goods in hot places, such as a garage, attic, above the stove, near a furnace or hot pipes, or anywhere in direct sunlight, can be detrimental to the food in the jar or its seal. At extended periods above 75°F, canned food can lose nutritional value. Light can cause both loss of nutrients and color changes, and in foods with fats or oils it can hasten rancidity. Light and/or high temps can also heat the air in the headspace of the jar, causing it to expend and break the seal of the jar. Above 95°F, food can actually spoil or harmful pathogens may be able to grow, rendering the food potentially unsafe.
To ensure quality and safety, store canned food in a cool, dry, dark place. The ideal temperature range is 50°F - 70°F. Do not store canned food above 95°F.
As for the actual canning process in hot weather, it’s best to can when your kitchen is no more than 75°F, as the jars’ cool-down time could be negatively impacted. If the jars cool too slowly, thermophilic bacteria could grow causing the food to spoil (and rushing the cooling process is not an option).
For further information on canning, visit the National Center for Home Food Preservation (NCHFP) or contact your local Cooperative Extension office.
Brought to you by the UC Master Food Preservers of El Dorado County
Last updated July 2025