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Halloween Climate Extremes

Halloween comes during a time of year that has highly variable weather. The long term trend is more consistent, as Octobers are warming across the U.S. On the world's current emissions track, very cold Halloweens will likely become less frequent over this century.

Halloween is upon us and the mid-fall celebration is well-known for its inconsistency in weather from year to year. Just like spring, the weather on any given day in the fall is highly variable. As a result, some years bring a Halloween with a last hurrah of late summer warmth and humidity. Other years bring cold, biting winds and early snows which can push well into the South. This is a reminder that weather is short term and highly variable. This week, we examine the extremes on Halloween in your market: highs, lows, and precipitation.

There is more consistency in the long term climate trend. Octobers across the U.S. continue to warm, nearly 2°F since 1970. Similarly, falls as a season are warming across the country, which is likely playing a role in changing fall foliage patterns. This warming is also reflected in the length of the growing season, which is increasing substantially in much of the U.S. The buildup of greenhouse gases from the burning of fossil fuels has already warmed the planet, and will continue to do so in the future. On our current path of carbon dioxide emissions, we would expect the number of unusually cold Halloweens to decrease gradually over this century.