Brew coffee with water between 195 and 205°F, or 91 to 96°C. Without a thermometer, that is water from a kettle that has just boiled and rested for about 30 seconds. Go toward the hot end for light roasts and the cooler end for dark ones.
That is most of what you need. Temperature matters, but it is a smaller dial than grind or ratio, and a few degrees either way will not ruin a cup. This guide explains why it matters, how to get close without special gear, and when it is worth adjusting.
Why temperature matters
Hot water dissolves the flavour out of ground coffee, and the hotter it is, the faster it works. That speed is the whole story:
- Too cool, and the water runs out of time before it has pulled out enough. The cup tastes sour, thin, and a little salty, the classic signs of under-extraction.
- In range, the water gets through the bright acids and on to the sweetness that balances them.
- Too hot for the coffee, mostly a risk with dark roasts, and it pulls harsh, bitter compounds out quickly. The cup tastes ashy and drying.
So temperature works the same way as grind: hotter water and finer coffee both extract more. That is why a sour cup can be fixed with either, and why changing both at once makes it hard to tell which one helped. See calibrating the grind.
Temperature by roast
Light roasts are dense and dry, and they resist extraction. Dark roasts are more porous and give up their flavour easily. So:
| Roast | Start at | Why |
|---|---|---|
| Light | 94–96°C (201–205°F), or just off the boil | Needs the extra heat to taste sweet, not sour |
| Medium | 91–94°C (196–201°F) | The middle of the range works |
| Dark | 88–91°C (190–196°F) | Hotter water pulls out bitterness fast |
You will see claims that light roasts want cooler water. That is backwards. A light roast brewed cool is one of the most common causes of sour coffee.
These are starting points. If the coffee tastes balanced, the number is right, whatever it is.
Temperature by method
Each method page on this site gives its own starting temperature. Most sit near the middle of the range:
| Method | Water |
|---|---|
| Pourover | 93°C (200°F) |
| French press | 93°C (200°F) |
| AeroPress | 91°C (195°F), and cooler for dark roasts |
| Drip | The machine heats it; a good one brews at 91–96°C |
| Espresso | 92–93°C (198–200°F), set on the machine |
| Vietnamese coffee | Just off the boil, 96°C (205°F) |
| Moka pot | Room-temperature water in the boiler |
| Turkish coffee | Cold water, heated slowly with the coffee |
| Cold brew | Cool or room-temperature water |
The AeroPress tolerates cooler water than other methods because the coffee sits fully immersed and you can stir it, so it extracts well even well below 90°C. Its page has a range for each roast.
The last three are different on purpose. A moka pot and Turkish coffee bring the water up to heat themselves. Cold brew makes up for cold water with time, which is why it needs so much more coffee; see the cold brew ratio.
Without a thermometer
You do not need one. Boiling water is a fixed point you can work from: 100°C at sea level, and it cools at a fairly predictable rate once the kettle is off.
- Just off the boil: about 96°C or a little above. Right for light roasts and Vietnamese coffee.
- About 30 seconds off the boil: about 93°C. The everyday default for pourover and French press.
- About a minute off the boil: roughly 90°C. A good place to start with dark roasts.
These are approximate. A full kettle holds its heat longer than a half-empty one, and a small kettle cools faster. They are close enough to brew with.
Pouring also costs heat. Water loses a few degrees on the way from the kettle to the coffee, and more into a cold brewer. Preheat the brewer, the cone, press, or mug, with hot water and tip it out before you start. For pourover, the step that rinses the paper filter does this for you.
A variable-temperature kettle is a genuinely useful upgrade once you brew pourover every day. It is not a first purchase; see what to buy for your first coffee setup.
Can you use boiling water?
Yes, more often than you might think. The brewer, the coffee, and the air all cool the water the moment you pour, so water poured at a full boil is no longer at 100°C when it reaches the grounds. Many light-roast recipes call for it.
Where boiling water causes trouble is with dark roasts, which can turn harsh and bitter, and when water sits boiling in the kettle for a long time. For a medium or dark roast, let it rest first. The glossary answer gives the short version.
At high altitude
Water boils at a lower temperature the higher you live: roughly 1°C less for every 300 metres, or 1,000 feet, of elevation. In Denver, at about 1,600 metres, water boils at around 95°C.
So at altitude, use water straight off the boil. It is already at the cooler end of the range, and resting it drops it lower still. If your coffee tastes sour at altitude even with boiling water, grind a step finer to make up the difference.
Adjust temperature last
Temperature is the finest of the dials. Grind changes the cup more, and it is easier to repeat, so fix grind first and reach for temperature when the grind is close but the cup is not quite there.
| What you notice | Try |
|---|---|
| Sour or thin, and the grind is already right | Hotter water, 2–3°C at a time |
| Bitter or ashy, especially a dark roast | Cooler water, 2–3°C at a time |
| Sour from a drip machine, whatever the grind | The machine may brew too cool; see is your machine the problem |
| Tastes fine, but different every time | Keep the rest time the same, and preheat the brewer |
Change it by a few degrees at a time, and change only temperature on that brew. If the cup still is not right, fix sour, bitter, or weak coffee works through the other causes.