When I take my kids on a winter picnic I often like to take some warm drinks with me. It's usually hot chocolate for the kids and coffee for me, or maybe some mulled wine.
I've also thrown an outdoor party of two where I wanted to keep drinks warm for my guests so everyone can enjoy tea and coffee throughout the event.
But how do you keep drinks hot in a cooler? And how long will they stay hot?
I've learned a few tricks over the years that works really well to keep drinks piping hot in your cooler and most of them can be done with normal household items.
You can keep drinks hot in a cooler using many easy methods that all utilize the same principles.
- Increase insulation using an insulated bottle, towels, or aluminum foil.
- Surround the drinks with heated pads or bottles to increase thermal mass.
- Preheat the drinks and cooler in order to maintain the temperature.
Drinks can stay hot in a cooler for hours if prepared correctly, and depending on your situation you can use different combinations of the methods below to help you keep your drinks hot and ready.
How to Keep Drinks Hot in a Cooler – Things to Keep In Mind
The methods on this list will all work due to a few basic principles, and you’ll want to keep these in mind when trying to keep your drinks hot.
Preheating the Drink/Cooler
The cooler isn’t going to make your drink any hotter. It can keep heat from escaping, but there isn’t any sort of heating mechanism.
Just like how in summer you want to pre-chill your cooler to maximize it's ability to hold ice when you're keeping drinks hot you can do the opposite.
To pre-heat your cooler fill it up with hot water from the tap (I don't put boiling water in my cooler because it can damage it but I know some people do). Leave the hot water in there for 20-30 minutes before discarding it, drying the cooler and then packing it with your warm drinks.
If you’re packing hot coffee or tea in your cooler for later in the day, make sure you put it in the cooler at its hottest so that it retains heat for longer.
You can also pre-heat the container you're putting your drinks in. This is a great way to keep drinks warm outside for longer.
The more insulation your drinks have and the closer the insulation is to the drink itself the better.
A cooler will act as good insulation but if theres lots of air in the cooler then heat will still escape.
Using towels or cardboard to insulate your drinks will help to keep them hot and fill up empty air space that makes your drinks go cold faster.
Increase Thermal Mass
The more thermal mass in your cooler, the longer your drinks will stay warm.
Just like how a bathtub stays warmer longer than a cup of water, a lot of thermal mass in your cooler will keep everything hotter for longer.
Filling space with heated pads or hot water bottles will keep things hot longer.
These are the main principles that we’ll follow to keep drinks heated in a cooler, and if you’re looking to pick up a cooler or think it’s time to upgrade your cooler, you may want to check out my guide covering the best coolers under $100.
Now that you know the basics, let’s get into the methods.
1. Use an Insulated Bottle or Thermos
Vacuum insulated bottles are designed to keep drinks hot for extended periods of time and they actually work much better than coolers do because a vacuum is the most effective insulation.
You can use an insulated thermos on it's own and your drinks will stay piping hot for hours, but by putting it in your cooler your drink will stay warm for longer – especially on those extra cold nights.
When you’re trying to keep drinks hot in a cooler, using an insulated bottle or a thermos is definitely where you should start.
Fill the bottle with your coffee or other hot beverage and try to place it in a spot in your cooler that’s surrounded by heat. If you’re packing multiple bottles, keeping them together will help them retain heat longer.
There are plenty of insulated bottles that make for great use on the beach or camping trips, I personally enjoy taking them to the beach since they’re sturdy and can put up with the sand.
The bigger the bottle the longer your drink will stay warm. For tea I fill up my large Stanley thermos which is around 48 oz or 1.5 L and it stays super hot for hours.
Tough and durable this vacuum insulated stainless steel flask will keep drinks hot for 6-10 hours or cold for over 24 hours at a time.
Features a leak resistant lid and a wide mouth opening to make for easier cleaning. Comes in 1.1, 1.5 and 2 quart sizes.
2. Wrap your Drinks in a Towel or Blanket
You might not have the luxury of a thermos so if you're keeping your hot drinks in a glass, ceramic or plastic container then adding insulation is an absolute must if you want to keep it warm for as long as possible.
Use a beach towel, bath towel, or blanket to wrap your drinks firmly. You can even use sweaters or thermal underwear to keep it warm.
This will provide insulation keeping the heat in for longer, and also secure your drink from making an impact with the walls of your cooler.
Although not as effective as a thermos, this method can serve as an alternative to an insulated bottle.
If you’re using an insulated bottle, wrapping it will be a bonus and help keep your drinks hot for even longer.
3. Fill Empty Space with Towels, Blankets, or Cardboard
Empty space in your cooler will cause your drinks to lose heat more quickly.
Using towels, blankets, cardboard, or even newspaper to fill these gaps can help prevent the heat from draining and keep drinks hot.
Filling empty space will also provide additional insulation to your drinks, and help prevent any heat damage to the walls of your cooler.
If you’re using a bottle that can get extremely hot on the outside, it’s possible for the heat to warp the plastic and insulation on the interior of certain coolers. Towels or blankets are a great way to prevent this.
4. Preheat Your Cooler
The walls of a cooler are made from a thick layer of foam containing pockets of air that prevent heat from getting in or out.
When you place your drinks in your cooler at room temperature, these air pockets will steal some of the heat from the drinks as they warm up.
In order to prevent this and maintain the heat of your beverages, you’ll need to preheat the walls of your cooler.
This can be done by simply filling up your cooler with warm water from the sink and letting it sit for about half an hour. Afterward, you’ll empty the cooler and allow it to dry before putting your drinks inside.
Avoid putting boiling water in your cooler as it can damage the walls and insulation (keep it under or around 120ºF for more expensive coolers.
5. Use Aluminum Foil
Aluminum foil does a great job of insulating against heat radiation, something that coolers are rarely designed to handle.
By wrapping the inside of your cooler with aluminum foil, it will actually reflect any thermal radiation emitting from your drinks and send it back to the source.
This means that the heat is reflected back at your drinks, keeping them hotter for longer.
Combined with towels or other insulation and then packed inside your cool you can expect your drinks to stay hot for hours even on the coldest days.
6. Use Heat Packs or Hot Bottles
Filling your cooler with heat packs or water bottles filled with boiling water is a great way to introduce more heat and thermal energy to the cooler.
Surrounding your hot drinks with heat will not only keep them hot for longer but also maintain the heat of the entire inside of the cooler for longer.
This is what I use if I want to keep milk warm for a hot chocolate bar or if I'm trying to keep food warm in my cooler.
You can use regular hot water bottles (like the ones you use in bed) or you can convert regular water bottles into hot water bottles. Nalgene bottles make great hot water bottles for this very purpose.