Whether it was the intense heat of Manassas, or a downpour at Chantilly or New Market, weather conditions played a vital role in the war. Often overlooked by historians, these weather conditions impacted everything from soldiers' drinking water to their overall well-being.

Weather was a major issue in the Civil War, and how it influenced soldiers' lives was a topic of study by military historians. Several civilians in the war kept meticulous records of daily weather, and these records have become invaluable for scholars studying the Civil War.

For instance, the Rev. C. B. Mackee, a Presbyterian minister living in the Washington suburb of Georgetown, recorded temperature readings every day during the civil war. These dutiful measurements spanned four years and remain very valuable for anyone researching the war in the eastern theater.

The hottest day of battle in Virginia was 9 August 1862, at Cedar Mountain. The thermometer reached a whopping ninety-eight degrees on that Saturday.

In fact, the heat index on that day was one of the highest ever recorded on the eve or during a major fighting event in the Virginia theater. Krick details that day's temperature data, and concludes that "the heat index on August 9 was the highest for any day of battle in Virginia."

Another example of a high-temperature engagement was the Battle of Prairie Grove in December 1861. The morning's temperatures were moderate, but the afternoon dipped to near freezing. Soldiers were unable to keep warm and slept on the ground or in flimsy tents.