Behind the Forecast: Outwitting the weather when baking

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Don't let the weather ruin your sweet treats. Learn how to avoid weather impacting your baking in this week's Science Behind the Forecast.
Published: Nov. 24, 2020 at 10:15 AM EST
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LOUISVILLE, KY (WAVE) - This topic is near and dear to my heart. I love to bake, and avid bakers know that the weather can have a significant impact on how sweet treats and savory temptations turn out. High humidity is often blamed for soggy pie crusts and deflating cakes, but air pressure also has an impact.

The National Weather Service defines relative humidity as

“A dimensionless ratio, expressed in percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated. Since the latter amount is dependent on temperature, relative humidity is a function of both moisture content and temperature. As such, relative humidity by itself does not directly indicate the actual amount of atmospheric moisture present.”

So in layman’s terms, relative humidity describes the amount of water vapor in the air compared to the total amount of water vapor that the air can hold at a particular temperature. Warmer air can hold more moisture than colder air. That means, even with an equal amount of water vapor in the atmosphere, there will be a higher relative humidity if the air is colder than if it was warmer.

When meteorologists mention humidity on-air, usually we’re describing the relative humidity.

Since warmer air can hold more water vapor, bakers typically run into more issues on those warmer and rainy days. The extra moisture effortlessly soaks into dry ingredients; this is why flour clumps more on humid days. Bakers can fight the higher humidity by extending the baking time by five-minute intervals. Also, decreasing the amount of liquid in a recipe is always a good idea. Experts recommend that bakers reduce the amount of liquid by one-quarter. If the batter is too dry once mixed, then bakers can add additional liquid.

As the altitude increases, the boiling point of water decreases.
As the altitude increases, the boiling point of water decreases.(Britannica Kids)

Another way to fight high humidity, store dry ingredients in a refrigerator or freezer. Refrigeration keeps them fresher, but they must return to room temperature before use, or cakes and bread will not rise properly.

Atmospheric pressure also impacts how baked goods turn out. If an area of low pressure is nearby (think cold fronts), then cakes will act as if baked at a higher altitude, where air pressure is also lower.

Water boils when as the heat rises, the pressure inside the water becomes greater than the pressure outside the water. Lower air pressure leads to lower boiling temperatures of water. Water boils at about 212°F at sea level but about 200°F at 6,000 ft. Since the water boils at lower temperatures, lower air pressure means more water evaporates before the baking process is complete. Also, less atmospheric pressure forces cakes and bread to rise more quickly.

Avoid deflating cakes by reducing leavening agents such as baking powder and baking soda. Reduce baking powder by half a teaspoon or reduce baking soda by a quarter teaspoon to limit the cake rise.

Adding two to three tablespoons of flour or a half-beaten egg whites to a cake batter traps the gas from the leavening process, which keeps the cake from deflating.

Hopefully, checking the forecast before channeling your inner Betty Crocker may help prevent a baking disaster.

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