As an expert sommelier and brewer, I can confidently say that drinking a hot beer is not the most pleasant experience. However, if you find yourself in a situation where your beer has warmed up, it is not necessarily undrinkable.
When beer is served at its optimal temperature, it enhances the flavors and aromas, providing a refreshing and enjoyable drinking experience. The ideal serving temperature for most beers is typically between 38°F and 55°F (3°C and 13°C), depending on the style. Anything above that range can start to affect the taste and overall quality of the beer.
If you accidentally left your beer out in the sun or in a warm environment for an extended period, it may have reached a temperature that is far from ideal. The heat can cause the beer to deteriorate more quickly, leading to off-flavors and a generally unpleasant taste. However, the duration of exposure to heat is a crucial factor to consider.
If your beer has only been slightly warmed for a short period, it is likely still drinkable. The flavor may not be as crisp and refreshing as intended, but it should not pose any health risks. In fact, some beer styles, like Belgian ales or certain stouts, are often served at slightly warmer temperatures to enhance their complex flavors and aromas.
That being said, if your beer has been subjected to prolonged or extreme heat, it may have undergone some undesirable changes. The heat can accelerate the oxidation process, leading to a stale or cardboard-like taste. Additionally, the carbonation levels may diminish, resulting in a flat beer.
In my personal experience, I once accidentally left a bottle of IPA in my car on a scorching summer day. When I finally discovered it, the beer was undoubtedly warm. Despite my initial disappointment, I decided to give it a try. Surprisingly, the beer still had some hoppy bitterness and citrus notes, although it lacked the refreshing crispness that I enjoy in IPAs. While it wasn't the best beer I've ever had, it was still drinkable.
To summarize, while drinking a hot beer is not ideal, it is generally safe to consume as long as it hasn't been exposed to heat for an extended period. The flavor may be compromised, but it's unlikely to cause any harm. If you find yourself in this situation, you can still enjoy your beer, although it may not provide the optimal taste experience you were hoping for.