When winter tightens its grip on southeastern Wisconsin, the dangers of freezing temperatures extend well beyond icy roads and frosty windshields.
This article explains which everyday items should never be left in a cold car, why they’re at risk, and how to protect both your health and your belongings during extended cold snaps.
Why Cold Weather Turns Your Car into a Hazard Zone
A parked vehicle in subfreezing weather effectively becomes a poorly insulated freezer.
Inside temperatures can drop rapidly and stay low, stressing materials, altering chemical stability, and compromising food safety.
Items that seem sturdy at room temperature can crack, burst, or quietly lose effectiveness once the mercury falls.
Aerosol Cans: Hidden Pressure Bombs in the Cold
Aerosol cans—including spray paint, de-icer, hairspray, and cleaning products—are particularly sensitive to extreme temperatures.
The pressurized contents and propellants inside can behave unpredictably as they cool.
In very low temperatures, the metal can and internal components can crack or rupture, leading to leaks or, in some cases, explosion.
This not only creates a safety hazard but can also spray chemicals across your vehicle’s interior, causing stains, corrosion, and lingering odors.
Water, Soda, and Beer: When Beverages Become Ice Bombs
Liquids expand as they freeze, and in a sealed container that expansion has nowhere to go.
Water bottles, sodas, and beer are all susceptible to this basic physics lesson.
As these drinks freeze, the pressure can cause plastic bottles to bulge and split and glass bottles or cans to burst or explode.
The aftermath is more than a sticky mess: sugar-laden drinks can attract pests, leave lasting stains, and in the case of beer, potentially shatter glass into dangerous shards.
Canned Foods: Silent Food Safety Risks
Many people assume canned foods are nearly indestructible.
In reality, they are vulnerable to damage from freezing.
When the contents of a can freeze, they expand, stressing the metal seams and potentially compromising the seal.
The USDA recommends discarding any canned foods that appear swollen, dented from freezing, or emit an off odor after thawing.
Even if the can doesn’t visibly burst, a broken seal can allow bacteria to enter and grow as the food thaws, posing a serious health hazard.
Eggs: Fragile Protein in a Hard Shell
Shelled eggs should not be allowed to freeze if you plan to eat them safely later.
When eggs freeze, the liquid inside expands and can crack the shell, creating an open pathway for microorganisms.
Food safety guidelines are clear: discard any eggs that crack when frozen.
If an egg freezes without cracking, it can be thawed in the refrigerator and then hard-cooked safely.
Never leave eggs in a parked car for long during subfreezing weather—bring them indoors promptly with the rest of your groceries.
Electronics: Batteries and Circuits Under Stress
Modern electronics—smartphones, tablets, laptops, and GPS units—are not designed to sit in a freezing car for extended periods.
Battery chemistry is especially sensitive to temperature extremes.
In the cold, you may see rapid battery drain, temporary malfunction, or, over time, permanent capacity loss.
Manufacturers typically caution against both operating and storing devices for long periods in subfreezing conditions.
Condensation can also form when a frozen device is brought into a warm environment, further risking internal damage.
Eyeglasses and Frames: Brittle in the Cold
Eyeglasses with plastic frames become more brittle and less flexible in low temperatures.
A pair left in a freezing car can crack when you later adjust them or put them on.
While glass lenses generally tolerate cold better than liquids, sudden temperature shifts and brittleness in frame materials combine to increase the chance of breakage—an expensive and inconvenient outcome in the middle of winter.
Medications and Insulin: Potency at Risk
Many medications, particularly insulin and other liquid formulations, have strict storage temperature ranges.
Freezing can irreversibly alter their structure, rendering them less effective or completely inactive.
If medications have been left in a freezing car, do not assume they are safe to use.
Consult a pharmacist or physician before taking any medicine that may have frozen.
For insulin users, this is especially critical; reduced potency can directly affect blood glucose control and health outcomes.
Practical Steps to Protect Your Belongings in Winter
With some planning and simple habits, you can greatly reduce the risks posed by freezing temperatures to your belongings and your health throughout Wisconsin’s winter season.
Consider adopting the following strategies every time temperatures plunge:
Cold-Weather Car Checklist
Make it a routine to bring sensitive items indoors whenever you park for more than a brief errand.
Key categories to remove from your vehicle include:
Here is the source article for this story: Take these things out your car during freezing cold weather in Wisconsin