Can I Leave A Beer In A Hot Car? The Impact On Your Brew

Is leaving your beer in a hot car safe? Many people have this same question. Unfortunately, leaving your favorite brew in a hot car can pose several risks – including reducing the shelf life of the beer and causing off-flavors that taste unpleasant or even make you sick.

 In this guide, we explore the risks and provide alternatives to keep your brew fresh and tasty. Can I leave a beer in a hot car? Find out now.

Can You Leave Beer in a Hot Car?

Leaving beer in a hot car is not usually recommended because of the damage it can cause to the beverage. The heat inside a car, even during mild days or on cool winter evenings, can rapidly accelerate the aging process and degrade its flavor.

High temperatures have adverse effects on beers, as chemical reactions alter their delicate balance of flavors and aromas while also increasing alcohol content simultaneously. It is also important to note that leaving beer in direct sunlight increases these risks significantly; regardless of season, only minutes of exposure may damage your brew.

Also, some cans may explode if left for extended periods due to overpressurization caused by rising temperatures resulting from heat trapped within vehicles. All said and done; if you must leave beer unrefrigerated for several hours or overnight, it’s best kept in darkness, away from excessive light and extreme temperatures.

How Heat Affects Beer in a Hot Car

Heat has a dramatic effect on beer, causing off-flavors, aromas, and potential alcohol content changes depending on the severity of exposure.


When beer is exposed to a hot temperature, several chemical reactions can significantly affect its flavor. High temperatures can lead to increased bitterness and a decrease in the perceived sweetness as elevated levels of intense hopping, such as Alpha Acids (humulone), isomerize quicker due to heat, causing an increase in happiness or aromatics released into the beer.

Heat can also accelerate oxidation which can cause off-flavors such as cardboard or wet paper taste. This occurs because higher temperatures cause an increased rate of molecular oxygen abbreviation from gas-liquid interfaces that alters certain flavors precursors available for release during fermentation.

Additionally, high temperatures are known to both reduce malt character and destroy some delicate hop volatile aromas leaving behind unsupported harsh flavors while producing unpleasant sulfurous odors leading to a skunking effect caused by photochemical reaction with UV light penetrating through glass/clear bottles.


Heat exposure can cause the beer to develop off-putting aromas. As heat accelerates oxidation, compounds such as ethanol and acetaldehyde are produced, which impart strong odors that do not match traditional beer fragrances.

This is due to chemical reactions caused by the breakdown of iso-humulones, a naturally occurring ingredient in hops that contribute a pleasant fruity aroma. When these molecules degrade, they release mercaptan, which produces an unpleasant sulfuric smell reminiscent of skunked beer even though no direct exposure to light has occurred.

The combination of burning alcohol with sourness gives any hot car beer an undesirable and rancid character on the nose, constantly referring to it as undrinkable for human consumption.

Alcohol Content

When beer is exposed to higher temperatures, its alcohol content can be affected. Heat accelerates the oxidation process in beverages and affects the flavor as well. Generally speaking, heat increases the speed of chemical interactions between other compounds that make up your brew, such as hops and grain, ultimately lowering alcohol levels.

Without proper cooling or storage precautions when leaving a beer in a hot car, the beverage may not stay cold enough to keep any existing alcoholic content intact.

Beer stored in overly hot environments might taste flat with an unpleasant off-flavor from prolonged exposure or result in low alcoholic content due to ingredients boiling away at nominal rates over time.

How Does Beer Spoilage Occur?

Heat accelerates oxidation

Oxidation is a normal process that occurs in beer, forming new flavors and aromas. It affects the color, taste, and overall quality of the brew. While this natural aging can improve some beers such as Barleywines or IPAs, oxidation produces off-flavors if it happens too quickly – before it has had time to mature properly.

This is where the heat comes into play; hotter temperatures speed up oxidation and cause harsh flavors like sherry or cardboard in beer much faster than cold temperatures. Heat also causes other chemical reactions that break down essential components of beer – hops, for example – altering flavor and aroma.

When exposed to high temperatures over an extended period, your beer will become oxidized more quickly, resulting in unpleasant flavors that can completely ruin your brew’s character.


Skunking is a chemical reaction that occurs when beer is exposed to sunlight for an extended time or when the beer is exposed to temperatures higher than 70 degrees. This results in an unpleasant and leverageable taste, characterized by rotten egg-like odors and off-flavors like diacetyl.

Skunking can occur in both bottled and canned beers as long as they are sufficiently exposed to light from UV rays or extreme heat. The reaction that causes skunk to be triggered by UV light breaks down hop-derived molecules, including iso-alpha acid, which creates a compound similar to the smell of a skunk hence the name “skunky” beer.

To prevent this, it’s best practice to keep your brew out of direct sunlight and store it in cool places away from any source of high temperatures, such as inside cars on summer days.

Riboflavin Degradation

When beer is exposed to high temperatures, it can lead to the degradation of certain compounds like riboflavin. This process results in some unpleasant off-flavors and off aromas, including sulfur-like notes, green apple flavors, and an intense fruity smell.

Riboflavin degradation also leads to a loss of foam stability and color changes during storage.

Excessive exposure to heat increases the metabolism inside the container, causing oxidative changes that contribute towards the generation of sulfury odors resulting from the breakdown of molecules containing sulfur atoms like disulfides which form unpleasant volatile organic compounds (VOCs).

The harsher smells are mainly noticed in dark beers due to their higher ratio of roasted malts; however, lighter-colored ales also suffer equally since they contain more levels than lagers.

Cans vs. Bottles – Which is More susceptible to heat damage?

Let’s dive into the debate on whether cans or bottles are more susceptible to heat damage. We’ll evaluate this based on three key impacts: taste, odor, and alcohol content.

TasteHeat can affect the taste of canned beer by disrupting the delicate balance of flavors. This is especially true for non-pasteurized and full-flavored beers.Bottled beer stored in high temperatures can suffer from similar flavor degradation. However, due to the bottle’s material, the effect can be slightly less pronounced than in cans.
OdorUnder extreme heat, canned beer can develop an unpleasant odor due to oxidation accelerated by high temperatures.Bottled beer is not immune to this, but the impact is usually less severe than canned beer.
Alcohol ContentThe alcohol content in canned beer is vulnerable to heat exposure. High temperatures can destabilize the alcohol, leading to a noticeable decrease in strength.While bottled beer also suffers from this drawback, the thick glass bottle provides better insulation against heat, slightly preserving the alcohol content.

Both cans and bottles have their vulnerabilities when it comes to heat exposure. In general, it’s best to avoid leaving beer in a hot car, irrespective of its packaging. Always strive for proper storage conditions to enjoy your brew at its best.

How Long Can Beer Be Left in the Heat Before It Goes Bad?

Beer should not be left in a hot car for too long, as even brief exposure to high temperatures can cause it to spoil and go bad.

Impact of temperature and duration

Concerning the impact of temperature and duration on beer when left in a hot car, the following table summarizes the effects on taste, odor, and alcohol content.

TemperatureDurationImpact on TasteImpact on OdorImpact on Alcohol Content
70-75 Degrees Fahrenheit1-3 DaysSlight alterations, subtle off-flavorsMinimal changesNo significant change
75-80 Degrees Fahrenheit4-7 DaysModerate changes, noticeable off-flavorsThe increased smell of oxidationMinor reduction in alcohol content
80-90 Degrees Fahrenheit1 WeekSignificant changes, pronounced off-flavorsA strong smell of oxidation and potential skunkingSignificant reduction in alcohol content
90+ Degrees Fahrenheit3 DaysBeer may become undrinkable due to intense off-flavorsThe potent smell of spoilageA potential substantial decrease in alcohol content

Please remember that these impacts could be amplified if the beer is subjected to these conditions multiple times. If cold beer warms up and is cooled again, it can experience a drop in shelf life and potentially affect its taste and quality. To maintain the quality of beer, avoid exposing it to excessive heat.

Signs of spoilage

  • Unusual color, as beer kept in a hot car for an extended period, can darken or lighten significantly.
  • The foul smell could indicate the presence of contaminants in the beer, like staling particles that produce off-flavors and odors
  • Flat taste – brewed hops may break down during extreme heating, resulting in a flat taste to the beer
  • Decreased carbonation – high temperatures can lead to decreased gas pressure levels and lower carbonation levels
  • Sourness – rapid aging due to heat can cause quicker production of sour compounds associated with bacteria growth
  • Visible mold growth on bottles or cans of beer left in high heat for prolonged periods

FAQs On Can I Leave A Beer In A Hot Car:

Can I leave a beer in a hot car?

Leaving your beer in a hot car is not recommended due to the potential risk of adverse reactions that could occur as heat from the sun causes it to expand and ultimately explode if left for too long – resulting in an unpleasant mess & potentially ruined vehicle should liquid seep into delicate components located inside.

How does leaving my beer in a hot car affect its quality?

Leaving your beer exposed to extreme heat can cause oxidation, affecting the overall taste and flavor, leading to skunk-like aromas similar to rotting cabbage or simply flattening out altogether with nothing but off-putting notes indicative of poor storage procedures still present after consumption.

How quickly does heat damage my beer when left in a hot car?

The speed at which beers become victim to environmental elements depends upon the caliber and varying temperatures found outside, along with things like sunlight exposure, closed cabins, etc. Generally speaking, however – anything above 85 degrees Fahrenheit for two hours per day could be enough time needed for oxidization problems surrounding certain varieties purchased during hotter climates/seasons, so it’s best avoided entirely whenever possible regardless of location or climate-controlled conditions inside automobiles used frequently throughout peak summer months then stored until more relaxed temperatures return come Autumnal (fall).

Can I keep my beers safe while traveling during warm weather?

 Yes – by utilizing airtight containers featuring proper insulation technology designed specifically around containing craft beverages securely without risk of spoilage caused over time through prolonged temperature fluctuations often occurring routinely both indoors & outdoors year round.– Additionally, investing confidently into coolers made out UV resistant materials also helps protect contents kept therein from direct sunlight penetration while providing ample space leftover closer to ice packs necessary aiming toward keeping

Final Take

It is essential to avoid leaving your beer in a hot car during the summer months. Heat accelerates oxidation processes and can cause off-flavors and reduce the shelf life of beer.

The heat can also contribute to skunking or chemical reactions that alter the taste and quality of your brews. Leaving cans in a hot car for an extended period could even lead to them exploding due to pressure from carbonation! Keep your beer stored in a cool place and drink it within its expiration date on the label – this will help you enjoy all its flavor, aroma, alcohol content, and freshness.

Dan Smullen Beer is my life profile

Hi, I'm Dan, founder of BeerIsMyLife. I've been an avid homebrewer for over ten years, and beer is my true passion. I've traveled all over the world, visiting breweries, tasting beer, as well as making my own batches. I set up this blog to share that experience with you.