We estimate the effect of extreme weather on life expectancy in the United States. Using high-frequency data, we find that both extreme heat and cold result in immediate increases in mortality. The increase in mortality following extreme heat appears mostly driven by near-term displacement, while the increase in mortality following extreme cold is long lasting. We estimate that the number of annual deaths attributable to cold temperature is 0.8% of average annual deaths in our sample. The longevity gains associated with mobility from the Northeast to the Southwest account for 4% to 7% of the total gains in life expectancy experienced by the U.S. population over the past thirty years.