Happy New Year! In honor of the day when folks change out their calendars, the featured chart presents one of the many calendar plots that you can generate on this website. The featured chart presents the number of daily issued Special Weather Statements (abbreviated SPS for fun legacy reasons) that contain a polygon by NWS Davenport. This product can be issued any time of the year and can sometimes cover quick hitting winter events, but it most often used to cover slightly sub-severe convective storms. The IEM Automated Data Plotter tool has a number of calendar plot generation apps, including one for SPC/WPC outlooks, daily observation summaries, and daily NWS warning counts.
The first day of 2026 started off a bit chilly with afternoon temperatures below freezing for nearly the entire state. Both Burlington (SE Iowa) and Sioux City (NW Iowa) had afternoon high temperatures of 28°F and that is the subject of today's feature chart. The top panel presents the difference in afternoon high temperature between the two sites by week of the year. The darker green colors indicate higher frequency and a simple weekly average is fit to the data with the plotted line. The bottom panel partitions the temperature difference by Sioux City average wind speed over the afternoon period. The top panel shows the difference between the two sites is the strongest during the cold half of the year, but the magnitude is only a few degrees.
There is still time to go back and review how the year 2025 stacked up. The featured chart presents the number of days per year that the high temperature was at least the given threshold value for Ames. The orange bars show the 2025 totals with the blue bars + labels representing the maximum value and which year(s) it occurred. The yellow dots show a simple long term average and the triangles show the minimum total on record. The year 2025 is shown above average for all plotted thresholds below 97°F. Totals for the previous year around 80°F are not far from record values. This chart is indicative of a climate change trend for Iowa, which is an increase in warm days, but not much for really hot days due to increased humidity levels during the summer.
Continuing the theme of looking back on 2025, today's featured chart computes the percentage of days each year with a high temperature of at least one standard deviation above average for Ames. The statistics for each year are computed over the present day period of record for the site, so that is a caveat to the plot. The usage of a standard deviation helps to normalize the departures as a day ten degrees above average during the summer is less frequent than during the winter, for example. That aside, last year comes in the top ten for having the largest percentage of such above average. The other years include some notable years during the Dust Bowl and also the drought year of 2012. The flood year of 1993 leads the bottom ten with a remarkable low count of such warm days!
In some regards, the past three to four weeks have been frustrating for most Iowans seeing the very warm air temperature forecasts to not materialize due to persistent low clouds and fog, as was the case again on Tuesday with record high temperatures relegated just to our west. Even with the disappointment, average daily high temperatures still have been very seasonably mild over this period as shown by the featured map presenting unofficial IEM estimated climate district average temperature ranks. A value of one indicates the warmest on record since at least 1893. A vast sea of red / ones can be readily seen with Iowa straddling the edge of the warmest departures. The other end of this see-saw is Alaska and northwestern Canada, which unfortunately the IEM does not produce similar maps for, but has seen a bitterly cold temperatures over this same period. This pattern does look to shift some later in January, but it remains to be seen if significant periods of cold weather will happen any time soon.
Yesterday's daily Feature bemoaned that the really warm temperatures had mostly kept just to the west of Iowa. On Wednesday, a decent portion of the state got to experience very warm air for the first week of January with Des Moines setting a record high of 60°F. The featured chart presents the warmest daily high temperature each year for Des Moines during the first week of each year. Only four other years have seen such a warm temperature during this period with plenty of years not even seeing an above freezing temperature during it. Much closer to average temperatures are expected over the upcoming days, but nothing much for seasonally cold values.
