The Fundamentals
Temperature is one of the most powerful levers in brewing. Hotter water increases solubility, meaning compounds dissolve faster and more completely.
But temperature does not affect all compounds equally. Acids dissolve quickly even at lower temperatures. Sugars need moderate heat. Bitter compounds require high temperatures to extract efficiently.
Rule of Thumb
Lower temperatures favor brightness and acidity. Higher temperatures favor sweetness and body—but risk bitterness if extraction goes too far.
Temperature and Extraction Speed
As temperature increases, molecular activity speeds up. Water molecules move faster, penetrate coffee particles more quickly, and carry away dissolved compounds more efficiently.
Temperature Zones:
85-88°C (185-190°F)
Low extraction zone. Acids dominate. Suitable for dark roasts or coffees you want to keep bright without bitterness. Slower extraction requires finer grind or longer time to compensate.
90-94°C (194-201°F)
Balanced zone. Most pour-over falls here. Good for medium roasts. Balances acidity, sweetness, and body without excessive bitterness.
95-96°C (203-205°F)
High extraction zone. Aggressive extraction. Best for light roasts that need maximum extraction to reveal sweetness. Risk of bitterness with medium or dark roasts.
Boiling (100°C / 212°F)
Too hot. Extracts excessively, including unwanted astringent compounds. Can scald delicate aromatics. Not recommended for pour-over.
Temperature by Roast Level
Different roast levels respond differently to temperature:
Light Roasts
Recommended: 94-96°C
Light roasts are dense and under-developed. They require aggressive extraction to access sugars trapped deep in the bean. High temperatures help dissolve these compounds without extending brew time excessively.
Medium Roasts
Recommended: 90-94°C
Medium roasts are more developed, so extraction happens more easily. Balanced temperatures preserve acidity while bringing out caramel sweetness. Most forgiving roast level.
Dark Roasts
Recommended: 85-91°C
Dark roasts are porous and fragile. They extract very quickly. Lower temperatures slow extraction, preventing over-extraction and excessive bitterness. Focus on body and chocolate notes.
Practical Temperature Control
Controlling temperature precisely requires either a temperature-controlled kettle or understanding heat loss.
Methods for Temperature Control:
- •Variable-temp electric kettle: Most accurate. Dial in exact temperature. Recommended for consistency.
- •Boil and wait: Boil water, then wait 30-90 seconds. Every 30 seconds drops temperature by approximately 5-7°C. Not precise but functional.
- •Thermometer: Use an instant-read thermometer to check kettle temperature before brewing.
Important: Water temperature drops during pouring and when it contacts the dripper. Your slurry temperature (the actual coffee bed) will be 3-5°C cooler than your kettle. This is normal.
Preheating your dripper and server with hot water minimizes heat loss. This is especially important for light roasts where every degree matters.