Everyone with a car should have some emergency supplies on hand, including water. But do you need to worry about your stored water boiling in the sun? The short answer is: no. However, there are some important things to consider when storing liquids in a hot car.

Summary:

• Stored water in a car will not reach its boiling point under normal conditions.
• Liquids like alcohol, however, can evaporate or even boil due to their lower boiling points.
• Clear plastic water bottles can become dangerous in direct sunlight, acting as magnifying lenses and potentially causing fires.
• Water boils at 212°F (100°C), but this temperature decreases with elevation, though higher altitudes are usually colder.
• Even in the hottest cars, the temperatures rarely get high enough to boil water.

Elevation Affects Boiling Points, But Not in This Case

The boiling point of water changes depending on atmospheric pressure. At higher elevations, where there’s less air pressure, water boils at a lower temperature. For example, at 5,000 feet, water boils around 203°F (95°C). But while elevation does affect the boiling point, it doesn’t matter much when it comes to a parked car.

That’s because the temperature inside a car, even on the hottest day, rarely reaches the levels needed to boil water. In fact, most cars don’t even get close to 180°F (82°C)—the temperature at which some alcohol starts to evaporate.

There’s a simple experiment that demonstrates how pressure affects boiling. If you put warm water in a syringe and pull back the plunger, reducing the pressure, the water will begin to boil at a much lower temperature. You can see this in action in the video below, where water boils at just 82°C (179.6°F).

On Mount Everest, water can boil at just 160°F (71.1°C), but the temperature is so low there that it’s impossible for water to reach that point. Similarly, in Death Valley, one of the hottest places on Earth, the highest recorded temperature was 129.9°F (54.4°C), still far below the boiling point of water.

How Hot Does a Car Get?

A study from Arizona State University found that cars can get extremely hot when left in the sun. On a summer day in Tempe, Arizona, researchers measured dashboard temperatures up to 157°F (69.4°C), steering wheels at 127°F (52.8°C), and seats at 123°F (50.6°C).

I did my own quick test. On a 92°F (33.3°C) day, I placed a thermometer in the trunk of my car, then moved it to the shaded driver’s seat, and finally to the sunny dashboard. Within five minutes, the temperature on the dashboard had exceeded 120°F (48.9°C), proving that the dashboard gets the hottest.

Another local auto detailer tested cars on a 120°F (48.9°C) day and found that the roof of a black Camaro reached 207°F (97.2°C), while the inside of the car was about 180°F (82.2°C). Still, that’s not enough to boil water.

So, unless you’re in a place with very low atmospheric pressure and extremely high temperatures—like a future climate scenario—your water won’t boil in the car.

Ambient vs. Surface Temperature

It's easy to confuse ambient air temperature with surface temperature, especially in a car. The air inside may feel cooler, but surfaces like the dashboard, seats, and steering wheel can be much hotter. In one study, the dashboard consistently stayed hotter than the surrounding air, though not by a huge margin.

Surface temperatures tend to lag behind ambient temperatures. For example, in a dishwasher, the water needs to be hotter than the required dish temperature to properly clean them. But again, cars aren’t designed to trap heat like that.

Don’t Leave Clear Bottles or Alcohol in Your Car

One thing you definitely don’t want to leave in a hot car is a clear, disposable water bottle. These can act like magnifying glasses when exposed to direct sunlight, potentially starting a fire. Plus, heat can cause harmful chemicals to leach into the water, especially from plastics.

Alcohol is also a concern. With a boiling point of around 132.8°F (56°C), substances like rubbing alcohol, hand sanitizer, and high-proof liquor can evaporate or even explode if left in a hot car. While it’s unlikely to create a major hazard, it could make a mess and reduce the effectiveness of your sanitizer.

So, while your water probably won’t boil, it’s still best to avoid leaving certain items in your car during the summer. Stay safe, stay cool, and always keep emergency supplies handy.

Outdoor Sun Shade Sail

Outdoor Sun Shade Sail,Sunshade fabric sails,Patio Shade Cover,Shade Cloth For Patio

Hebei Charlotte Enterprise Co., Ltd. , https://www.hbcharlotteawning.com