Baking Sourdough in Different Climates and Seasons

Why Climate Rules Your Timeline

Sourdough is a temperature-driven system, and the single most useful fact to internalize is the rough doubling rule: for every 8 °C (about 15 °F) rise in dough temperature, fermentation runs roughly twice as fast. A bulk ferment that takes 8 hours at 20 °C / 68 °F can finish in 4 hours at 28 °C / 82 °F, and stretch past 12 hours at 12 °C / 54 °F. That is why the same recipe behaves like a different beast in a July kitchen versus a January one, and why copying a timeline from a video filmed in someone else's climate is the most common cause of over or under fermented loaves.

The fix is to stop baking by the clock and start baking by dough temperature and visual cues. If you dial in one number to control your process, make it desired dough temperature (DDT), the temperature you want the mixed dough to hit so fermentation lands in a predictable window.

Hot Climate Baking (Above 27 °C / 80 °F)

In a hot kitchen the enemy is speed. Bulk fermentation that a recipe pegs at 5 hours may be done in 3 to 4 hours, and an over-fermented dough goes slack, sticky, and tears instead of holding a taut skin. Shape earlier than any recipe tells you and judge by rise, not minutes: pull the dough when it has grown about 50 percent and shows a domed, jiggly surface with visible bubbles at the edges of the container.

• Chill the water. Use cold or iced water to drop the initial dough temperature. This is the fastest way to buy back control in a hot room.
• Shorten the bulk. Plan for a 3 to 4 hour bulk at 28-30 °C / 82-86 °F and check the dough every 30 minutes in the back half.
• Retard in the fridge. During heat waves, run the whole bulk or the final proof in the refrigerator at 4 °C / 39 °F. Cold retarding for 8 to 16 hours also deepens flavor and makes scoring easier.
• Keep the starter cool. Feed at a high ratio (1:5:5 up to 1:10:10) and refrigerate between feeds so it does not turn sharply acidic on the counter.

Cold Climate Baking (Below 20 °C / 68 °F)

In a cold kitchen fermentation crawls. Bulk can stretch to 8 to 12 hours, and below 15 °C / 59 °F a starter may barely move. This is not a defect. Slow, cool fermentation builds more complex, nuanced flavor, but it demands a warm, stable spot and patience.

You have several ways to build a warm, consistent proofing spot without special gear. Consistency matters more than hitting an exact number.

• Oven with the light on. The bulb holds most ovens at 24-27 °C / 75-80 °F. Verify with a thermometer, since some ovens run hotter.
• Cooler with warm water. Set the dough in a picnic cooler next to a jar of water at 40 °C / 104 °F and refresh it every few hours.
• Warm the water. Mix with water at 30-35 °C / 86-95 °F to lift the DDT toward 25 °C / 77 °F from the start.
• Feed a livelier starter. In winter, drop to a lower ratio (1:2:2 to 1:3:3) so the culture peaks fast enough to stay strong.

Humidity and Hydration

Ambient humidity quietly changes your effective hydration. In a humid climate, flour picks up moisture from the air, so a formula written for 75 percent hydration can behave like 78 percent in your bowl. Reduce added water by 5 to 10 g per 500 g of flour and judge by feel: the dough should be tacky but still release from your hand. In a dry climate the opposite happens. Flour is thirstier and dough surfaces skin over fast during bulk and proof.

A light mist of water on the dough before covering, or a sealed container instead of a loose towel, prevents a dry skin that would otherwise crack during oven spring.

The Fridge as a Climate Equalizer

Cold retarding is the one technique that works in almost every climate, and it is worth leaning on year round. Once the dough is shaped, holding it at 4 °C / 39 °F slows yeast activity to a near stop while the lactic and acetic bacteria keep working slowly, which is why a retarded loaf develops deeper flavor and a crisper crust. In a hot kitchen the fridge rescues a dough racing toward over-proof; in a cold one it lets you split a long process across two days without babysitting.

A practical rhythm: build strength and complete bulk during the day, shape in the evening, then retard the shaped loaf for 8 to 16 hours overnight. Bake it straight from the fridge, cold and firm, which improves oven spring and makes scoring cleaner. If you only adopt one habit from this guide, an overnight cold retard is the one that smooths out the widest range of conditions.

Seasonal Swings and Your Starter

Across a full year the same kitchen can swing 8-10 °C between summer and winter, which shifts bulk time by 2 to 4 hours. Rather than fight it, adapt the schedule: run tighter summer timelines backed by cold retards, and lean into leisurely room-temperature winter ferments. Your starter follows the seasons too, peaking fast in summer and sluggishly in winter.

Match the feeding ratio to the season. In summer, higher ratios (1:5:5 to 1:10:10) slow the culture so it does not over-acidify between feeds. In winter, lower ratios (1:2:2 to 1:3:3) keep it active enough to peak on schedule. Track peak time and dough temperature in a notebook and adjust one variable at a time.

A Year-Round Framework

Pull the threads together and the whole approach fits on one card. Measure dough temperature after mixing, target a DDT near 25 °C / 77 °F using water as your lever, and then let the season set your bulk window: roughly 3-4 hours when the dough sits at 28-30 °C / 82-86 °F, 5-8 hours at 22-24 °C / 72-75 °F, and 8-12 hours below 20 °C / 68 °F. Trust the 50 percent rise and the jiggle test over any printed clock, adjust hydration for the air in your kitchen, and shift your feeding ratio with the seasons. Change one variable per bake, write down what happened, and within a handful of loaves your process will hold steady no matter what the weather outside is doing.