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Fermentation temperature guide

Fermentation temperature guide for ales, lagers and kveik: maker yeast ranges in °F and °C, why beer runs warmer than the room, and how to hold it steady.

Updated November 2026 · 7 min read

Two open fermenting buckets with rocky krausen on top
Photo: David Blaikie, CC BY 2.0, via Flickr
The short version
  • Ferment at the temperature the yeast maker lists, measured in the beer, not the room. Clean ales usually sit around 64–68°F (18–20°C).
  • Active fermentation makes heat. In the first 2–4 days the beer can run several degrees above the air around it.
  • Pitch at the low end of the range, hold steady through the peak, then let it rise a few degrees to finish clean.
  • Lagers need about 48–59°F (9–15°C); kveik is happy from the 70s to around 100°F, per the makers.
  • A dual-stage controller in a fridge or chamber, with the probe taped to the fermenter under insulation, is the most reliable fix.

This fermentation temperature guide answers the question that decides more beer quality than any recipe tweak: how warm should the beer be while yeast works? Too warm, and ale yeast throws fruity esters and hot, solvent-like fusel alcohols. Too cold, and fermentation stalls before it finishes. Steady is as important as the number itself.

The ranges below come from the yeast makers’ technical sheets (Fermentis and Lallemand), and the off-flavor causes come from BYO and Palmer’s How to Brew. Temperatures are given in °F with °C in brackets.

What temperature should beer ferment at?

Start with the yeast sheet. Each strain has a working range set by its maker. Within it, cooler fermentation gives cleaner flavor and warmer gives more fruit and spice, which some styles want (Belgian ales, hefeweizen) and most don’t.

Maker temperature ranges for common dry yeasts

YeastTypeMaker rangeNotes
Fermentis SafAle US-05American ale64.4–78.8°F (18–26°C)Clean at the low end
Fermentis SafAle S-04English ale64.4–78.8°F (18–26°C)Fast, flocculent
Lallemand LalBrew NottinghamEnglish ale50–77°F (10–25°C)Tolerates cool fermentation
Fermentis SafLager W-34/70Lager53.6–64.4°F (12–18°C) idealThe classic dry lager strain
Lallemand LalBrew VossKveik77–104°F (25–40°C); optimum 95–104°FFull attenuation in 2–3 days at optimum, per Lallemand
Lalvin EC-1118Wine, cider, mead50–86°F (10–30°C)Not a beer yeast

Source: Fermentis product pages; Lallemand technical data

Dry yeast by the maker’s numbers

YeastUseFermentation tempDoseAttenuation / toleranceRehydration
SafAle US-05
Fermentis		Ale (American)18–26°C (64.4–78.8°F)50–80 g/hL78–82%; not listed on the product pageOptional: ≥10× its weight of sterile water or boiled, hopped wort at 25–29°C (77–84°F), 15–30 min; or direct pitch at or above fermentation temperature
SafAle S-04
Fermentis		Ale (English)18–26°C (64.4–78.8°F)50–80 g/hL74–82%; 9–11% ABVOptional: ≥10× its weight of sterile water or boiled, hopped wort at 25–29°C (77–84°F), 15–30 min; or direct pitch at or above fermentation temperature
SafLager W-34/70
Fermentis		Lager12–18°C (53.6–64.4°F)80–120 g/hL80–84%; 9–11% ABVOptional: ≥10× its weight of sterile water or boiled, hopped wort at 15–25°C (59–77°F), 15–30 min; or direct pitch at or above fermentation temperature
LalBrew Nottingham
Lallemand		Ale (English)10–25°C (50–77°F)50–100 g/hL78–84%; 14% ABVDry pitching is the maker's preferred method (no significant difference vs rehydration, per Lallemand)
LalBrew Voss (kveik)
Lallemand		Ale (kveik)25–40°C (77–104°F)
Optimum 35–40°C (95–104°F) per Lallemand		50–100 g/hL76–82%; 12% ABVPer the sachet
Lalvin EC-1118
Lallemand		Wine, cider, mead10–30°C (50–86°F)25 g/hLFerments dry; 18% v/v (subject to conditions)35–40°C (95–104°F) water for 20 min with Go-Ferm Protect Evolution (30 g/hL), then temper to within 5–10°C of the must

Sources: Fermentis: SafAle US-05 product page; Fermentis: SafAle S-04 product page; Fermentis: SafLager W-34/70 product page; Lallemand: LalBrew Nottingham technical data sheet; Lallemand Brewing: LalBrew Voss Kveik Ale Yeast product page; Lallemand: Lalvin EC-1118 technical data sheet. 1 hL = 26.4 US gal, so 50 g/hL ≈ 1.9 g per gallon. Follow the sachet you buy; makers update their sheets.

A maker’s full range is the span where the yeast will ferment, not where it tastes best. For clean American and British ales, most brewers aim a few degrees above the bottom of the range, then let it rise near the end.

Why the beer is warmer than the room

Fermentation is exothermic: yeast releases heat as it converts sugar. A 5 gal (19 L) batch at peak activity can run several degrees warmer than the air, and the difference is largest in the first 2–4 days, exactly when most flavor compounds form. BYO notes that fermenter temperatures run higher than ambient, which is why a 70°F room can mean a beer well into the mid-70s.

A shallow open fermentation vessel in a brewery covered in foam
Fermentation makes heat; big batches need active cooling.Photo: Picardin, CC BY 4.0, via Wikimedia Commons

That is the main reason to measure the beer itself. A stick-on strip on the fermenter wall, a thermowell, or a controller probe taped to the side and covered with a folded towel or foam all read much closer to the beer than an air thermometer.

A temperature schedule for clean ales

  1. Chill to pitching temperature

    Pitch at or slightly below your target. Fermentis allows direct pitching of US-05 onto wort at or above fermentation temperature; pitching into warm wort and cooling later means the first, most important hours happen too warm.

  2. Hold through the peak (days 1–4)

    Keep the beer near the low-to-middle part of the range, for example 64–66°F (18–19°C) for US-05. This is when esters and fusels form.

  3. Free-rise to finish (days 4–7)

    As activity slows, let the beer warm 3–5°F (2–3°C). Warmer, still-active yeast cleans up diacetyl and acetaldehyde and finishes attenuation.

  4. Confirm final gravity

    Take readings 2–3 days apart. When they match, fermentation is finished; see how to use a hydrometer.

  5. Cold crash (optional)

    Chill to near freezing for 1–3 days to drop yeast and haze before packaging. Expect suck-back of airlock liquid as the headspace cools; a sanitized blow-off or a CO2-pressurized vessel avoids it.

  6. Record what happened

    Log the set point, the peak beer temperature and the days. The brew-day log has a fermentation temperature table.

Lagers, Belgians and kveik

Lagers

A clip-on glass kettle thermometer with Fahrenheit and Celsius scale
Every yeast family has its own temperature window.Photo: Steven Jackson from USA, CC BY 2.0, via Wikimedia Commons

Lager yeasts ferment cold, typically 48–59°F (9–15°C); Fermentis lists 53.6–64.4°F (12–18°C) as ideal for W-34/70. After most of the sugar is gone, a diacetyl rest at about 60–65°F (16–18°C) for 2–3 days lets yeast reabsorb buttery diacetyl, then the beer is cooled for weeks of cold conditioning (lagering). Winter garages and basements at 48–55°F help, but a fridge with a controller is the reliable route.

Belgian and wheat ales

Saison, Belgian and hefeweizen strains are chosen for their esters and phenols, and many brewers let them run warmer by design. Follow the strain’s sheet and the recipe; there is no single right number.

Kveik

Norwegian farmhouse kveik strains ferment fast and clean at temperatures that would ruin most ale yeasts. Lallemand lists 77–104°F (25–40°C) for LalBrew Voss, with 95–104°F optimal. That makes kveik the summer option for brewers without temperature control. See the kveik yeast guide.

How to control fermentation temperature

Options from cheapest to most precise

MethodCoolsHeatsPrecisionBest for
Interior closet or basement~ Only as cool as the room✗~ Swings with the houseAles in spring and fall
Swamp cooler (tub of water, wet towel, frozen bottles)✓ Several degrees✗~ Needs daily attentionSummer ales on a budget
Insulated fermentation bag with ice packs✓✗~Small spaces
Heat wrap or belt with a controller✗✓✓ With a probeCold garages, winter
Fridge or chest freezer + dual-stage controller✓✓ With a heat wrap✓ ±1–2°FAles and lagers year-round
Glycol chiller with coil or jacket✓~ With a heater✓Conicals, several fermenters

Source: Maker manuals (Inkbird, BrewBuilt); Palmer, How to Brew

A bimetal dial thermometer mounted on a stainless vessel
Measure the beer, not just the room.Photo: Mike Shaw, CC BY-SA 4.0, via Wikimedia Commons

The fridge-plus-controller setup is the standard because it handles both seasons. A dual-stage controller has one outlet for cooling (the fridge) and one for heating (a wrap or small heater). Set a differential of 1–2°F so the compressor doesn’t short-cycle, and use the controller’s compressor delay if it has one.

Probe placement

Tape the probe to the side of the fermenter at mid-height and cover it with a small square of foam or a folded towel, so it reads the beer rather than the fridge air. A thermowell (a tube that dips into the beer) is even better. Never leave the probe dangling in air; the controller will chase the wrong temperature.

Small-space and budget options

The temperature control and summer situation page collects controllers, chambers and heat wraps in one place.

Garage brewing through the seasons

Garages swing hard: cold nights in winter, heat that can pass 90°F (32°C) in summer, and big daily swings in between. That is fine for storage and terrible for fermentation without control.

  • Winter (cold garage around 48–55°F): lager season. Ales need a heat wrap and controller, or move indoors.
  • Spring and fall: ales in an insulated chamber; watch overnight drops.
  • Summer: ales only in a fridge or chamber; otherwise brew kveik.
  • Any season: keep fermenters off bare concrete in winter and out of direct sun always.

Electric gear in a garage belongs on a GFCI-protected outlet. Controllers have load ratings; the Inkbird ITC-308 listing gives 1100 W at 110V. Check that the fridge and heater together stay under the controller’s rating.

Mistakes to avoid

  • Measuring air, not beer. The beer runs warmer at peak fermentation.
  • Pitching warm and cooling later. The first day sets much of the ester profile.
  • Big swings. A drop of 10°F overnight can make yeast drop out and stall; a spike drives fusels.
  • Crashing before fermentation is finished. You lock in diacetyl and leave sugar for bottle bombs.
  • Skipping the diacetyl rest on lagers. Buttery flavor is the usual result.
  • Overloading a controller. Check the wattage rating against the fridge and heater.
  • Fermenting in sunlight. Light and heat both damage beer.

Tasting something off? Match the flavor to its cause in beer off-flavors.

Who needs what

  • Brewing in a stable basement: a stick-on thermometer and patience may be enough for ales.
  • Garage or attic, or any lager plans: a fridge or chest freezer, a dual-stage controller and a heat wrap.
  • Hot climate, no fridge: kveik strains or a swamp cooler.
  • Several fermenters at once: a glycol chiller with coils or jacketed conicals.

Gear picks for this guide: best fermentation temperature controllers and best fermentation chamber setups.

VerdictControl the beer’s temperature, not the room’s: pitch at the low end of the maker’s range, hold steady through the first four days, then let it warm a few degrees to finish. A fridge with a dual-stage controller makes that easy in any season.
Yeast pitch rate calculatorYeast pitch rate calculator: cells needed for ales and lagers by volume and gravity, dry yeast grams from…Printable brew-day log and recipe sheetFree brew-day log: record recipe, water and salts, mash, gravities, yeast, fermentation temperatures,…

Questions

What temperature should beer ferment at?
At the temperature the yeast maker lists, measured in the beer. For clean American ales such as US-05, about 64–68°F (18–20°C) is a common target; lagers ferment around 48–59°F (9–15°C); kveik runs from the 70s to about 100°F.
What happens if fermentation is too warm?
Ale yeast makes more fruity esters and fusel alcohols, which taste hot or solvent-like. Very high temperatures can also stress yeast and leave off-flavors.
What happens if fermentation is too cold?
Yeast slows down and can drop out before the beer is finished, leaving it sweet and under-attenuated. Warm it gently into the range and swirl to rouse the yeast.
Where should I put the temperature probe?
Tape it to the side of the fermenter at mid-height and cover it with foam or a folded towel, or use a thermowell that dips into the beer. Don’t leave it measuring air.
Can I use a mini fridge for fermentation?
Only if your fermenter fits with the door closed. Many mini fridges have a freezer plate or shelf in the way. A chest freezer or full-size fridge is easier.
How do I keep beer warm in winter?
Use a heat wrap or belt controlled by a temperature controller with the probe on the fermenter. Lift the fermenter off cold concrete and insulate it.
Do I need temperature control for kveik?
Usually not in summer. Kveik strains such as LalBrew Voss ferment from about 77 to 104°F (25–40°C) per Lallemand. In winter you may need to keep it warm.

Sources

  1. Fermentis: SafAle US-05 product page
  2. Fermentis: SafAle S-04 product page
  3. Fermentis: SafLager W-34/70 product page
  4. Lallemand: LalBrew Nottingham technical data sheet
  5. Lallemand Brewing: LalBrew Voss kveik ale yeast
  6. BYO: Judging off flavors
  7. John Palmer, How to Brew (fermentation chapters)