Coffee in summer: Yay or nay? Tips on caffeine in hot weather

Yes, coffee is a part of summer whether it's hot or iced. If you only remember one thing from this article, make it this: Coffee is mostly water, so it's a reliable source of hydration. And maybe you'll be surprised to learn that in some conditions, a hot cup of coffee may even help cool you down. When's the best time to reach for iced coffee and when is it better to brew a near-boiling one?

Are you team iced or hot?

The defining condition here is not the thermometer, but the humidity levels. Hot coffee is best for dry heat while oppressive, humid weather calls for an iced one.

Most people will best enjoy a hot cup of coffee in the morning or an early afternoon. If you drink it slowly, you'll be rewarded with a full aroma, body, and bitter depth. It also makes a great company in air-conditioned offices. On the other hand, iced coffee will instantly refresh you – it's tailor-made for hot afternoons, travels, or for long drives to your vacation destination.

Coffee in the summer is not your enemy

One of the most annoying myths is that when it's hot, coffee 'dehydrates you'. That's actually not true, since coffee is mostly water. Caffeine itself is slightly diuretic, but to actually experience its effects, you'd have to drink extreme amounts of coffee daily.

Research on human body hydration agrees that the issues arise with doses above 400 mg of caffeine per day. Until you reach those levels, coffee can hydrate you almost as well as water. And those who indulge in coffee regularly gradually develop resistance to the diuretic effects.

Of course, water is still the pinnacle of hydration not only in the summer. Coffee cannot replace it. But if you fear that two to three cups of coffee a day will dehydrate you, then there's no need to worry.

Can hot drinks really cool you down?

If you get a hot drink, your body will produce more sweat, since that's how it gets rid of excess heat – the resulting evaporating sweat can cool you down more than a cup of hot coffee warms you up. The research of this effect was spearheaded by the physiologist Ollie Jay. In his 2012 study, he found that a body stored less heat after a hot beverage compared to a cold one.

Dry heat vs. Humid heat

• Dry heat: sweat evaporates quickly, your body's natural A/C is going full-swing. A morning filter or an espresso will help keep you energized even in the summer.
• Oppressive, humid heat: saturated air, sweat doesn't evaporate and hot coffee won't help you. Get a cold brew, iced americano, or an espresso tonic.

But the resulting difference in body temperature is not that dramatic, so drinking hot coffee by the liter in the heat of the summer isn't ideal either.

Cold brew as the perfect option

If we were to pinpoint one amazing summertime coffee drink, it would be cold brew: coffee extracted in cold water. It doesn't come in contact with hot water at all. Cold water pulls out some substances slower and in lower amounts. The result is less bitterness, lower acidity, and naturally sweeter taste.

TThis summer hit didn't just appear in some hipstery coffee shop 10 years ago. This brewing method has existed since at least the 17. century in Japan, where coffee was slowly dripped with cold water for up to eight hours. It's said that the Japanese people learned this technique from the Dutch merchants who needed a long-lasting coffee drink to survive long voyages where fire wasn't an option.

How to cold brew

Coarsely grind your coffee (as you would for a French press) and cover it with cold water in a ratio of 1:10. Rest in a fridge for 12-24 hours. The easiest option is Hario Mizudashi 600 ml – Cold Brew Machine: you just add the coffee and water and by the morning, you'll have your drink.

You can find detailed instructions in our How to Cold Brew article or browse other interesting ideas in our blog section. Since cold brew isn't as bitter as regular coffee, it's best to use light or medium roast arabicas with fruity taste profiles.

Was your homemade cold brew too weak or acidic? These are the three most common reasons:

• too finely-ground coffee (muddy, bitter result)
• not enough coffee (watery taste)
• short steeping (weak, acidic result)

To prevent these, grind your coffee coarsely, try to keep the 1:10 ratio, and give your cold brew plenty of time to steep – even overnight.

How much caffeine do we drink?

You need to be especially careful with cold brew. Due to the low coffee-water ratio and long extraction, it contains much more caffeine that you'd expect from such a mild, refreshing beverage.

Did you know that in the hottest countries of the world, drinking hot beverages is a very common practice? From Turkey to north Africa, hot coffee is as much a part of the summer as lemonade.

What to watch out for

Don't rely on coffee as your only source of hydration – water is still the best option. Aside from that, watch the caffeine, especially if you combine coffee with cola or energy drinks. Don't drink coffee too late in the day to avoid disturbing your sleep schedule. Also watch the sugar in iced coffee as well as syrup and cream content. It's easy to accidentally create a caloric bomb.

ManuCafe barista tip: a good summer cold brew is easily recognizable – you won't need to sweeten it at all. Also, get your coffee freshly roasted, use a fruity arabica, and grind it right before you plan to brew it.

If we summarize the facts, we come to an easy conclusion: don't stress too much about coffee in the summer. Don't feel pressured to give it up or drink a jug of water to balance it. And don't feel bad for having a nice, hot espresso on a tropical day.