Sumner, IA Weather

Key Messages

- Above average temperatures continue through mid-week. Areas of patchy overnight fog possible once again Wednesday morning.

- Breezy conditions develop Friday and Saturday, especially in northern and western Iowa. Rain chances return to the same areas Saturday.

Short Term

Issued at 342 AM CDT Wed Oct 21 2026

Not many changes to the forecast today as high pressure positioned over the Great Lakes continues to keep us fairly quiet! Skies across central and northern Iowa remain mostly clear. Meanwhile a weak shortwave has initiated light showers across southwest Iowa this morning. Rain totals have been very light, with only a few locations recording a few hundredths of an inch. We have added slight precipitation chances across the south as a few rain drops have been able to overcome the dry low-level air and reach the surface. This shortwave will continue to push eastward through Wednesday morning, bringing a mix of sun and clouds to southern Iowa. Another item to monitor will be areas of patchy fog across portions of central and northern Iowa this morning. However, taking a closer look, winds will be around 5-8 mph combined with limited moisture make dense fog unlikely. REFS guidance currently shows a under 30% probability of visibilities dropping below one mile.

Wednesday into Thursday

Once the shortwave slides through southern Iowa, skies will turn mostly sunny statewide with another warm day expected. Highs are expected to climb into the mid to upper 70s later today, which is nearly 15 degrees above average for this time of year. Our average temperature is in the upper 50s to lower 60s. Thursday will be another warm day, though we expect a bit more cloud cover across northwest Iowa. Stronger moisture transport will be positioned across the Plains on Thursday; combined with 850mb southwesterly winds over northwest Iowa, this should yield a slight bump in cloud coverage throughout the day.

Long Term

Issued at 112 PM CDT Tue Oct 20 2026

Later this week, a 500 mb trough will move into the pacific northwest, dislodging and merging with the west coast cutoff low currently blocking the overall pattern in the US. By Friday, this merged 500 mb trough will push into the western CONUS and attempt to shove the ridge off eastward. However, this ridge becomes sandwiched between the western trough and another southeastern US trough, placing Iowa right along the trough/ridge interaction. The net result for Iowa will be a southwest flow regime aloft, with some increasing moisture in both the low and mid-levels as a result. As energy ejects out of the trough and along the ridge this weekend, Iowa will see a few things result. First, tightened low-level pressure gradients will promote breezy conditions both Friday and Saturday. The breeziest conditions will be over the northern and western parts of the state both days, and could result in some slightly elevated fire weather concerns over far northwest Iowa.

Precipitation chances also make a return this weekend, as a cold front is pulled into the state by the surface low passing to our north. Iowa will be fairly well removed from the main synoptic forcing of the low, but ascent along the cold front combined with increased moisture through the column will provide some potential for rain Saturday into Sunday. Rain probabilities will be highest across northwestern Iowa nearer to the main moisture transport axis (~40% chance), with lower likelihood where drier conditions are present farther into central Iowa (10 to 20% chance). Southern and eastern Iowa generally remain dry until the boundary slowly pushes farther south and east into Sunday and Monday. Behind this boundary, temperatures become more seasonal in the low 50s to upper 60s, although exact temperatures will be dependent on how prominent of a cold push results.

Aviation

Issued at 1042 PM CDT Tue Oct 20 2026

VFR conditions are expected through the TAF period. Little change in expectations since last issuance. Patchy fog is possible in northern Iowa again Wednesday morning at KMCW, however potential is too low for inclusion at this time. Light wind from the south overnight will shift to from the southwest Wednesday afternoon.