Humidity and Sourdough: How to Bake in Dry or Wet Climates

Short answer: in dry climates (below 30% humidity), dough surfaces dry fast; cover well and increase hydration slightly. In wet climates (above 70% humidity), dough takes longer to dry and may feel stickier; reduce hydration slightly and use more bench flour.

Why humidity matters

Humidity affects:

• Surface drying (dough top can dry into a hard skin)
• Flour absorption (in humid air, flour absorbs ambient moisture)
• Crust formation (dry air browns crust faster)
• Mold risk (high humidity = mold-friendly)

Most home bakers don't think about humidity, but it's a real variable.

Common humidity ranges

Air conditioning lowers humidity; humidifiers raise it.

Dry climate adjustments

In low-humidity kitchens (<35%):

For dough:

• Cover well during bulk (plastic wrap or damp cloth)
• Mist the dough surface during folds
• Cover the basket during cold retard

For hydration:

• Slightly higher (75% feels like 73% in dry air)
• Or add 5–10g extra water

For baking:

• Steam matters more (less ambient moisture)
• Use a steam tray + ice cubes
• Dutch oven works well (traps natural steam)

Wet climate adjustments

In high-humidity kitchens (>65%):

For dough:

• Slightly reduce hydration (75% feels like 77% in humid air)
• Use more bench flour
• Be careful not to add too much (changes recipe)

For storage:

• Bag bread in cloth (not paper) to prevent re-absorbing moisture
• Watch for mold on bread (humid + room temp = mold-friendly)
• Refrigerate flour to prevent absorption

For starter:

• Less likely to dry out
• Mold risk slightly higher (cleanliness matters more)
• Activity normal

Why dry air dries the surface

A dry kitchen pulls moisture from any exposed surface. For sourdough:

• Bulk dough surface dries (forms a skin)
• Skin is hard to fold into the dough
• Prevents oven spring at the surface

Counter the effect:

• Cover during bulk
• Mist if needed
• Don't leave dough exposed to air

Why humid air slows surface formation

A humid kitchen slows surface drying. Effects:

• Dough surface stays soft longer
• Easier to handle high-hydration dough
• Less skin formation

This is actually a benefit for high-hydration sourdough.

A real-world adjustment

If you bake the same recipe in two different climates:

Dry kitchen (Phoenix, 25% humidity):

• 75% hydration recipe → feels like 73%
• Add 5g water

Humid kitchen (Miami, 75% humidity):

• 75% hydration recipe → feels like 77%
• Reduce 5g water (or use more bench flour)

The recipe is the same; the adjustment is for moisture absorption.

Crust formation

In dry air:

• Crust forms fast in the oven
• Bake covered longer to allow expansion
• Steam phase is critical

In humid air:

• Crust forms more slowly
• Less aggressive crust development
• Easier to over-bake the inside

Mold and humidity

Mold loves:

• Humidity above 70%
• Temperature 70–85°F
• Sugar (not bread, but starter)

In humid climates:

• Wash starter jars more often
• Don't leave starter exposed for hours
• Check bread daily for mold (it appears faster)

Bread storage in humid climates

Humid climates make bread mold faster:

• Counter, cloth bag: 3 days max (vs 5 in dry)
• Refrigeration extends life but stales bread
• Frozen storage is most reliable

Bread storage in dry climates

Dry climates dry bread fast:

• Counter, sealed plastic: 3 days
• Bread bag with crust intact: 4 days
• Counter, exposed: 1 day before stale

Counter the dryness with proper bagging.

A coastal climate consideration

If you live near the ocean:

• Humid air also brings salt
• Doesn't affect sourdough significantly
• Slight tendency for mold

A high-altitude humidity note

High altitude is usually drier. Combine altitude adjustments with dry-climate adjustments.

A seasonal humidity shift

Within one location, humidity varies:

• Summer (humid in many regions)
• Winter (heated air = dry)
• Spring/fall (variable)

Some bakers note that their bread changes seasonally — same recipe, different result. Humidity is one cause.

A simple home test

Buy a hygrometer ($10):

• Measure your kitchen humidity over a week
• Note the range
• Identify if you're dry, average, or humid

This tells you how much adjustment your bakes need.

Summer vs winter baking

Summer (warm, humid):

• Faster fermentation (heat)
• Slower drying (humidity)
• Easier to handle high hydration
• Mold risk for stored bread

Winter (cool, dry from heating):

• Slower fermentation
• Faster surface drying
• Need to cover dough more
• Bread keeps well

Adjust schedules and storage seasonally.

A final note

Humidity is a subtle variable. Most bakers don't think about it.

But if your bakes have changed and you can't figure out why, humidity is worth checking. Especially if you've moved or seasons have shifted.

A $10 hygrometer + a notebook of bakes will reveal patterns.

Once you understand your kitchen's humidity, you can adjust hydration and timing to match — and produce consistent bread regardless of weather.