Waterloo, IA 50704 Weather

Key Messages

- Seasonably warm temperatures and dry conditions prevail through mid-week. Patchy fog possible in the mornings.

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

Short Term

Issued at 112 PM CDT Tue Oct 20 2026

The weather in Iowa remains dry and seasonably warm as 500 mb ridging and surface high pressure maintains influence today. Sunny skies prevail through mid-day, although scattered high clouds will begin to spread up into southern Iowa this evening as a subtle shortwave propagates through the upper level ridging. This approaching wave will bring slightly tightened pressure gradients today, causing light to occasionally breezy winds around 10 to 15 mph with gusts up to 20 mph over northwestern Iowa. With the approaching wave, a few deterministic model solutions are depicting some light rain over northern Missouri/southern Iowa early Wednesday morning. However, despite the slightly better saturation in the mid- levels, the low- levels remain quite dry overnight. This will likely limit anything more than a rogue sprinkle from reaching the surface, and therefore the forecast remains dry overnight. By early Wednesday morning, some guidance is hinting at more isolated fog development, but probabilities for less than a mile are low around 30% or less in REFS guidance and only about 10% from the HREF, again favoring northern Iowa.

The status quo continues through Wednesday and Thursday, with warm, dry conditions during the day and efficient cooling during the overnight. NBM temperatures have generally been too muted with the magnitude of the diurnal curve during this pattern, being a few degrees too cold during the days, and too warm overnight. Therefore, have continued pushing temperatures toward the upper end of guidance during the days and lower end of guidance at night through Thursday. The end result is forecast highs in the mid 70s and about 10 to 15 degrees above normal for this time of year (Normal Max Temps: northern Iowa -58F, central Iowa - 61F, southern Iowa - 63F). Lows will generally be in the 40s to 50s, around 10 degrees higher than normal (Normal Min Temps: northern Iowa - 35F, central Iowa - 38F, southern Iowa - 42F). More fog potential is expected Wednesday night into Thursday morning as clear skies and light winds continue under the surface high.

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 625 PM CDT Tue Oct 20 2026

VFR conditions are expected through the TAF period. 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.