Best Temperature for Fermentation? (Practical Guide)

This practical guide gives you the best temperature for each type of fermentation (kombucha, kefir, tempeh, yogurt, koji, etc.), helping you to easily achieve successful home fermentations!

Rest assured, it is rare that you need to control the temperature… except for certain sensitive fermentations, where it is essential. In other cases, it is just very useful to know which temperatures give good results — and which ones could cause problems.

Why Is Temperature Important?

Fermentations are created by living microorganisms. For a fermentation to be successful, these little creatures need to be happy. One of the most important factors for their well-being is temperature.

Just as you would not like to work in a T-shirt at 68°F (10°C), microorganisms also have their preferences. Too cold? They go to sleep. Too hot? They die or run wild. Therefore, you need to find the right zone for each of them.

This guide does not delve into the microbiological details of each fermentation but provides you with enough information to make informed decisions easily.

🌡️ Cold fermentations (≤ 68°F / 20°C)

Notes

• Beer (Lagers): slow fermentation with specific yeast (Saccharomyces pastorianus) that ferments at low temperatures. Result: refreshing flavour with no aftertaste.
• Hard cider: Cool temperatures better preserve the aromas. The warmer the temperature, the drier and less fruity the cider will be.
• Mead: Fermenting at low temperatures prevents defects (sulphur or solvent tastes). The result is sweeter and more aromatic.
• Wine (white/rosé): Cool temperatures preserve delicate aromas. Above 68°F (20°C), floral and fruity aromas fade.
• Fermented vegetables: best results around 65°F (18°C). For full details, check out: What Is the Ideal Temperature for Lacto-Fermentation?

🌿 Room Temperature Fermentations (68-82°F / 20-28°C)

Notes

• Kombucha: At 82°F (28°C), the aromas are more complex. Below 72°F (22°F), fermentation is slow. Above 95°F (35°C), yeast may become overactive or die.
• Water kefir: The warmer the temperature, the faster the fermentation, resulting in a dry and very fizzy drink. The colder it is, the milder and less fizzy the kefir will be.
• Milk kefir: At around 72°F (22°C), the result is creamy and balanced. If the temperature is too cold, the whey will separate, resulting in a less homogeneous texture.
• Sourdough: A mild temperature (~77°F/25°C) produces a soft, moist bread. The colder it is, the slower the fermentation and the more acidic the flavour (depending on the duration).
• Viili: Can be made at room temperature (~68°F/20°C), but produces better results at around 82°F.
• Wine (red): Tannins are more easily extracted at these temperatures.

🌡️ Warm Fermentations (86-99°F / 30-37°C)

Notes

• Vegan yogurt: Ferments at 68°F (20°C) but gives much better results between 77 and 95°F (25-35°C).
• Tempeh: ideal temperature around 86°F (30°C). Caution: tempeh produces its own heat as it ferments, so it needs to be monitored, and the heat turned off after 24 hours to prevent it from overheating.
• Koji: Requires a stable temperature and humidity environment for 36 to 48 hours.
• Matsoni: Can be incubated at room temperature but gives best results at 95°F (35°C).
• Yogurt L. Reuteri: Maintaining the correct temperature range is critical for success.

🔥 Hot Fermentations (≥ 99°F / 37°C)

Notes

• Natto: Requires constant heat. Too low a temperature is detrimental to texture and flavour development.
• Yogurt: The best results are obtained by maintaining the correct temperature range.
• Amazake: Enzyme activity stops below 122°F (50°C). The temperature must be maintained for several hours for optimal conversion of starch into sugars.

A Few Explanations About Temperatures

• The temperatures shown generally give the best results: good taste, good texture, effective fermentation.
• It is sometimes possible to ferment outside these ranges. Follow your recipe or the instructions for the culture used, which may have their own specific characteristics.
• The colder it is, the slower the fermentation will be! This is true for all types of fermentation. For example, kombucha can take 30 days at 68°F (20°C) … but only 4 days at 95°F (35°C).
• Avoid direct sunlight, which causes sudden variations and can overheat your fermentations.
• Cheese making is one of the most technical types of fermentation, and it depends heavily on the strain used, the type of milk… and the temperature, which can vary greatly depending on the recipe and the steps involved.

When Does an Incubator Become Really Useful?

If the temperature in your room is relatively stable and corresponds to the recommended temperature in the chart, then an incubator is not required.

An incubator is useful when:

• Fermentation must take place at a temperature above 86°F/30°C (tempeh, natto, koji, yogurt, etc.).
• You want consistent results, summer as well as winter.
• Your kitchen is cool or poorly insulated.

An incubator is essential when:

• You are fermenting sensitive cultures (amazake, L. Reuteri, koji).
• Your fermentations have already failed due to cold or heat.

🎯 Key takeaway: An incubator prevents failures and improvisations and expands your possibilities — without stress.

A Little Science

Fermentation is made possible by the action of various bacterial strains, yeast, molds, and enzymes: natural proteins that convert sugars, proteins, or starches into simpler compounds — acids, gases, alcohols, aromas, etc.

But for this biochemical magic to happen, certain conditions must be met: temperature, duration, humidity, etc.

Too low a temperature slows down the activity of microorganisms and enzymes. Too high a temperature can kill microorganisms or destroy the enzymes they produce.

This is why temperature control, or thermal regulation, becomes crucial in certain sensitive fermentations (such as koji, amazake, or specific probiotic yogurts). Conversely, more rustic fermentations (such as sauerkraut or kefir) are more tolerant of variations.

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