HUNTSVILLE, Ala. — July 4th is traditionally a hot day across the Tennessee Valley. It should be hot. It's summer and more obvious it's July. If we dig a little deeper we'll discover that July 4th historically is getting warmer on average.
Across the United States July as a month is getting warmer. There were 242 cities analyzed and it was discovered that 170 of those have recorded a 1° rise in the average July temperature since 1970. 106 of the 242 cities recorded a 2° rise in their July average since 1970.
Note: This is the average temperature the whole month. This isn't the average high, but the average temperature.
Huntsville's average temperature in July has risen 2.9° since 1970.
This may not seem like much since 1970, but it creates big changes in temperature extremes.
These extremes are noticed where the record warm days are outpacing the record cold days across the country.
In Huntsville it's not as extreme and actually some decades such as the 1950s, 1960s, 1970s, and 1980s the record cold days outpaced the record warm days.That is a long time locally and somewhat contradicts the national trend. Since the 1990s the record warm days have outpaced the record cold days.
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So on the extreme end, the warmest July 4th on record in Huntsville was 102° in 2012. The coldest July 4th was 57° in 1961.
Birmingham has seen similar extremes on July 4th. The hottest was 102° in 1921 and the coldest was 58° in 1924.
Looking at the Birmingham climate for the average temperature in July we see that it has risen 2.4° since 1970.