Full-blown winter appears here to stay with another round of snow impacting Iowa on Monday into Tuesday. Totals from this event were much lighter with just an inch or two most commonly reported over southern and southeastern Iowa. As a reminder, the IEM generates these maps for snowfall events that have at least an arbitrarily chosen two inch or greater report and/or significant travel impacts. You can find previous event maps for this year and previous years by following the "winter2526" tag associated with this feature message. The next snowfall event arrives this evening, but totals are again expected to be on the light. A bit of quieter weather arrives for the remainder of the week.
The snowfall from this past weekend was quite intense for November. The featured chart presents top 10 daily snowfall totals for Des Moines during the month of November. There are caveats galore with such a listing including difficulties of snowfall measurement, varying periods of record, and most importantly: snowfall events are typically long duration and often cross arbitrary 24 hour boundaries more so than heavy rainfall events. All those caveats aside, the total from Saturday at 8.9" comes in third place for the month of November. This was also the case for Waterloo, with its 9.3" coming in third place as well.
After a mild start on Wednesday morning, an arctic front swept the state and ushered in much colder temperatures and the coldest air of the season to date. Low temperatures this Thursday morning are well below zero and likely record lows for today for many sites in the state. The featured chart looks into the accumulated frequency of having the season's first low temperature of the given threshold by the given date of the season for Ames. The chart plots as a percentile over all years, so there are some years that failed to reach the given threshold and that is why the accumulated value does not reach 100 in all cases. The side table shows the percentile dates for each threshold. Having such cold weather by 4 December comes in around the 10-25th percentile of so, so about once or twice per decade to experience such cold temperatures this early for the given thresholds plotted.
The featured chart presents monthly average temperature departures for Ames with the monthly Niño 3.4 index values since the start of 2018. The value of this index drives the designation of either La Niña (negative value) or El Niño (positive value) state with values between -1 and 1 considered as "weak". So we have spent much of 2025 in a weak La Niña state with the present forecast not calling any additional strengthening, so remaining weak. Much is made of using this index to make monthly/seasonal scale forecasts for weather over the globe due to the importance of the equatorial Pacific Ocean basin for global atmospheric circulations. As the chart shows, it is certainly not a simple relationship between this index and monthly temperature departures for a location in the center of Iowa!
Our bout of early winter season snowfall storms continued on Saturday with a stripe of snowfall painted from northwestern to east-central Iowa. The largest reports received so far approached ten inches over far northwestern Iowa. The first few storms presented snowfall measurement challenges, but this one fell quickly and didn't blow around too much. More chances of snowfall are in the forecast, but also a period of above freezing temperatures this week.
The featured chart checks in on the accumulated time spent at or below a given wind chill temperature threshold for Des Moines over the season to date period. This is based on hourly observations and is expressed on the chart in units of days, which hopefully makes the total number of hours more tangible. Each season's accumulation is plotted along with a simple average, the 25th and 75th percentile, and this seasons accumulation (blue line). This season shows that we have a below average total for the most extreme values, but above average between about 10 and 25°F. We will experience warmer weather on Tuesday with temperatures even above freezing for much of the state, but strong winds and colder air on Wednesday will certainly add to the wind chill hours for the season!
Temperatures warmed very nicely on Tuesday with the entire state reaching above freezing values. This warmer air is being swept out of the state though by very strong winds with NWS Offices like Des Moines issuing a High Wind Warning for gusts around 60 MPH. The featured chart presents the number of such warnings by year as issued by NWS Des Moines. This year's total of six is double that of any year over the modern period of record. It is interesting to see no such events over the previous two years.
While not for a snow producing winter storm, the extreme corner of northeastern Iowa was clipped with three to four inches of snowfall on Tuesday night into Wednesday, so meeting the arbitrary two inch threshold for IEM map generation and winter storm accounting! Iowa was rather fortunate for this event as the blowing snow threat did not materialize after significant melting occurred with the above freezing dew points on Tuesday and coincident strong winds. Our next round of snow is here already this Thursday with a few inches of snowfall expected over a stripe from the NW to SE corner of Iowa.
The very active start to the winter season continued on Thursday with a compact system producing a stripe of snow from the northwest to southeast corner of the state. An inch or so was the most common with a few higher isolated reports near Fort Dodge and larger totals found over far southeastern Iowa. The next round of snow arrives this evening along with bitterly cold air for the weekend. For those of you that are already tired of winter, warmer weather does look likely next week with a number of days with temperatures above freezing.
Another snow storm impacted Iowa during the weekend, making for the third such weekend in a row! The featured map attempts to provide an analysis of the snowfall reports from the most recent storm and not include reports from the storm that ended early Friday morning. This stripe of snow was not too far displaced from the previous stripe of snow from the aforementioned storm. A number of locations reported upwards of five to six inches of snow. It is somewhat a shame that all this recent snow will not stick around until Christmas as warmer weather this week will melt much of it.
