On average, June is Iowa's wettest month. So it seems appropriate for the start of June to look into precipitation climatology. The featured chart presents the official NCEI daily climatology for Des Moines along with the previous official version. NCEI updates the climatology every ten years to represent a recent 30 year period. A climatology of precipitation is somewhat tricky as the dataset is dominated by dry days (zeros) and heavy rainfall events that skew simple daily statistics. Average daily values become somewhat meaningless, but the annual cycle is still illustrative as shown by the featured chart. It is interesting to see the July dip that shows up in the current (1991-2020) climatology, which is likely due to a number of dry Julys during the 2010s.
Monday was yet another rather warm day with high temperatures well into the 80s for most of the state. For Des Moines, it was the 19th day so far this year with a high temperature in the 80s. The featured chart presents the climatology, 2025, and 2026 totals for year to date days with a daily high temperature within the given temperature range. The totals within the 70s and 80s are both well above average for 2026, but interestingly about average for the 60s. The forecast for the rest of the week looks to continue totaling up days with highs in the 80s.
The featured chart compares yearly precipitation totals between Cedar Rapids and Ames. Blue bars indicate Cedar Rapids was wetter than Ames by the given margin and red bars indicate Ames was wetter. This chart nicely shows the variability that exists on the yearly time scale between two sites that have an overall average difference of just 0.37 inches (~1% of the yearly total). There have been just under 20 years with the difference between the two sites over 10 inches (~30% of the yearly total). The overall frequencies of which site is wetter is not that much different with Ames only have six more such years. This just goes to show how variable precipitation can be over even considerable periods of time.
It has been a somewhat strange year for severe weather to date for the United States. April was very busy for severe weather in and around Iowa, but it continued to be mostly quiet over the southeastern US. May was about the exact opposite of April with much quieter weather, but also for much of the rest of the country as well. The featured chart looks into an aspect of this by totaling up the number of Severe Thunderstorm and Tornado watches issued by the Storm Prediction Center for the year to date period. The top panel shows the total number of watches with the second panel totaling the number of watch outline polygons (note they are no longer the official watch area, but a close approximation) that touched Iowa. The bottom panel plots the percentage touching Iowa. Interestingly, 2026 comes in with the highest percentage since 2004!
