Bend, Oregon sits at roughly 3,600 feet above sea level. David Anthes noticed early on that his results didn’t match what recipes described, and that altitude was a significant part of the reason.
How Altitude Affects Fermentation
Lower atmospheric pressure at altitude allows gases to expand more easily. In sourdough, this means the carbon dioxide produced by wild yeast during fermentation expands faster and more aggressively than it would at sea level. The practical effect is that bulk fermentation moves faster at altitude — sometimes significantly. David Anthes consistently sees his dough reach the same level of development 20 to 30 percent faster than sea-level recipes suggest, particularly during warmer months.
This matters because overfermented sourdough is harder to recover from than underfermented dough. A loaf that has pushed past its ideal fermentation window before shaping will be slack, hard to shape, and prone to spreading in the oven rather than rising. David Anthes adjusted by shortening his bulk fermentation windows and checking the dough earlier than the recipe directed until he understood how his kitchen’s conditions translated to actual dough behavior.
Adjusting Hydration
Altitude also affects evaporation. Lower atmospheric pressure means water evaporates more readily, both during baking and during the mixing and shaping stages. Dough can dry out slightly faster during long bulk fermentation at altitude, and the finished crust can set more quickly in the oven. David Anthes compensates by increasing his base hydration by 2 to 3 percentage points compared to what sea-level recipes call for and keeping his dough covered during bulk fermentation to minimize surface drying.
He made these adjustments gradually rather than all at once. Jumping hydration too quickly without understanding how the dough handles the change creates new problems. Adding one adjustment at a time and documenting the result let him isolate what was actually working.
Oven Temperature and Baking Time
Water boils at a lower temperature at altitude — about 202 degrees Fahrenheit in Bend rather than 212 degrees at sea level. This affects the moisture environment inside the baking vessel during the first phase of baking. Steam forms more readily, which can be an advantage for oven spring but also means the crust may set differently than expected. David Anthes raises his oven temperature by 10 to 15 degrees Fahrenheit compared to sea-level recipes and shortens the covered baking phase by 3 to 5 minutes to compensate.
The uncovered phase — when the crust browns and crisps — often completes faster at altitude as well. David Anthes checks the internal temperature of his loaves with a thermometer rather than relying solely on color. A finished sourdough loaf reads between 205 and 210 degrees Fahrenheit internally. This check eliminates the guesswork that visual browning alone cannot resolve at altitude.
What Stays the Same
Not everything changes at altitude. The fundamental chemistry of sourdough — starter activity, gluten development, shaping technique, scoring method — remains the same. The adjustments David Anthes makes are incremental modifications to timing, hydration, and temperature rather than wholesale changes to the process. His altitude-adjusted notes now serve as his baseline, and he rarely thinks about the elevation anymore. It became part of how he understands his kitchen, the same way humidity and seasonal temperature shifts are factored into every bake.