A Tale of Two Temperatures: Decorah's May Mixed Heat and Chilly Nights

Your contribution today guarantees Decorah News is asking the questions tomorrow. Act now. DECORAH — According to meteorologist and Luther College faculty member Richard Bernatz, May 2026 in Decorah brought a spring mix of warm, sunny days and cooler nights. Data compiled by the National Weather Service showed the month concluded with an average daily temperature of 60.7 degrees, 1.7 degrees above the historical average. While the month did not break any all-time records, it ranked among the warmer Mays on record. Of the 131 Mays since 1895, 89 were cooler and 41 were warmer. The most notable aspect of the month was the contrast between daytime and nighttime temperatures. The average high temperature was 75.4 degrees, 4.1 degrees above the historical average. Temperatures reached 90 degrees May 27 and 28. Meanwhile, overnight lows averaged 45.9 degrees, 0.7 degrees below normal. The month's coldest temperature was 28 degrees on May 2. The wide temperature range affected energy demand, resulting in 203 heating degree days, 25 fewer than normal, and 68.5 cooling degree days, 25.9 more than normal. May was drier than normal despite an otherwise wet spring. Total precipitation measured 2.78 inches, 1.46 inches below the historical average of 4.24 inches. Measurable precipitation fell on nine days, compared with the typical 11 or 12 days. The heaviest 24-hour rainfall total was 0.75 inches May 16. No snowfall was recorded during the month. Historical records indicate May 2026 was relatively dry. Since 1895, 97 Mays have been wetter and 32 have been drier. Looking at the rolling 12-month period, a pattern of sustained warmth remains evident. Eleven of the past 12 months recorded above-average temperatures, with only December 2025 posting a slight dip below normal. Precipitation has also generally trended above average. Seven of the past 12 months were wetter than normal. Despite May's precipitation deficit, Decorah maintains a 12-month precipitation surplus of 13.70 inches, largely due to exceptionally wet conditions in August 2025 and April 2026. Make your inbox your go-to for local news! Sign up for the free newsletter and get timely updates, special features, and more.