textproduct: Des Moines

KEY MESSAGES

- Warm and dry conditions today through mid-week. Heat indices in the 90s to near 100F.

- Isolated fog possible again tonight, mainly over southeast Iowa.

- Warm temperatures last through the end of the work week, although rain may return by the weekend.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 228 PM CDT Sun Jul 12 2026

Warm, summer-like conditions are in place over all of Iowa today. Winds are light, skies are clear and temperatures are warm thanks to the high pressure ridge now establishing itself overhead. East southeasterly flow yesterday and today has brought drier low-level air into the area, keeping dewpoints a few degrees lower today than yesterday, albeit still moist in the low to mid 60s. Temperatures are generally on pace with where they were this time yesterday, but with slightly drier conditions, highs will likely warm a few degrees more today, reaching the mid to upper 80s. With the surface high firmly entrenched in Iowa tonight, winds will go calm and skies will clear, leading to yet another night of prime radiational cooling. This opens up potential for more fog development, but the drier dewpoints and marginally warmer airmass will mean more cooling will be needed to reach saturation tonight compared to previous. Still, isolated pockets of fog will be possible prior to sunrise early Monday morning as cold air pools in low lying areas and localized saturation occurs. Widespread fog appears unlikely at this time.

The forecast generally remains status quo through at least the first half of the work week. The warmest 850 mb temperatures are expected to round the 850 mb ridge sitting directly overhead, keeping the warmest temperatures to our north and west. With no significant changes in air mass in Iowa, surface heating and thermal mixing will drive temperatures from day-to-day, seeing a couple degree increase each day. This will put highs in the upper 80s to low 90s Monday, then generally the low 90s on Tuesday, then increasing with each day through mid-week. Aside from the initial dry punch yesterday, the moisture also doesn't see significant day-to-day change, at least through advective components. Evapotranspiration and wet soils throughout the corn belt will contribute moisture to the surface layer each day, peaking around mid-morning then falling off steadily as the boundary layer mixes into the afternoon. With surface dewpoints remaining steady, if not slightly increasing, through the week and high temperatures following suit, expecting heat indices to climb into the upper 90s to near 100F. Fortunately, it looks likely we will stay below our 105F heat advisory criteria through the first half of the week, as even if dewpoints end up higher than anticipated, ambient temperatures won't be as warm, and vice versa. Therefore, no plans for heat headlines at this time.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 228 PM CDT Sun Jul 12 2026

A Canadian long wave trough will dig southeastward into the northeastern CONUS through mid- to late- week, which attempts to shunt the 500 mb ridge overhead back to the west. As this occurs, the surface high pressure will begin to weaken, transitioning us to a more transient surface pattern over Iowa. This increases the spread in temperature solutions among deterministic and ensemble guidance through the end of the week. The general trend seems to be continued warming into the weekend, although NBM may be running too hot with forecast highs in the mid 90s and dewpoints in the 60s. Should dewpoints increase into the 70s, highs would likely be closer to the low 90s. Adjustments have been made to the forecast to account for this, but will need to continue to monitor trends. In addition to temperatures, the weakening high and increased moisture Thursday into Friday may bring back rain chances to the state. This is a low confidence scenario, especially with the late week pattern still in flux, so the forecast remains dry at this time. Severe chances will be better assessed in the coming days, but weak flow should help mitigate severe chances through this period.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1052 PM CDT Sun Jul 12 2026

No changes from previous with light winds and clear skies expected to prevail through the TAF period outside of the low chance for patchy fog development into Monday morning. Best chances still remain near KOTM and left 6SM BR from previous TAF issuance. Although visby could drop lower at times, confidence in those impacts within 5SM of the terminal is too low for inclusion.

DMX WATCHES/WARNINGS/ADVISORIES

None.