textproduct: Des Moines

KEY MESSAGES

- Warm temperatures continue Today and Saturday. High temperatures approaching record values on Saturday.

- Increased fire weather concerns today and especially Saturday due to warm and dry conditions over western into central Iowa.

- Milder temperatures Sunday and Monday.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 315 AM CDT Fri Mar 20 2026

Thermal ridging to our west was responsible for much warmer temperatures yesterday, and this ridge will continue to build in from the west today and Saturday. The large 500 mb high pressure sitting over the western CONUS has kept Iowa on it's periphery, putting us in a northwest flow pattern. Subtle waves of energy passing through the northwest flow will pass through this flow, but the gulf moisture stream will remain cut off from the central US, negating any precipitation concerns. Therefore, the main story Today through the weekend is unseasonably warm and dry conditions. Temperatures today will be a few degrees warmer than yesterday, with some locations in the southwest half of the state making a run at the 80s. However, the hot/dry conditions really come to a head on Saturday, as the western CONUS high breaks down and the thermal ridging to our west is shoved south and eastward toward the state. Southwesterly flow at the surface and westerly flow aloft will advect warm, dry air into the state, allowing temperatures to soar into the mid and upper 80s on Saturday. Many sites will be approaching their daily records, all of which were set back in 1938. More details provided in the climate section.

With the warm and dry conditions today and Saturday, there will be some concern for elevated fire weather conditions. This is especially true on Saturday, as relative humidity values in west central Iowa fall into the low to mid 20 percent range. Fortunately, pressure gradients are fairly weak through this same period, and we will reside in a warm air advection regime, which should help to dampen winds on Saturday. Some of the short range guidance does indicate a very deep mixed layer on Saturday. This would allow the mixed layer to tap into slightly higher winds aloft (around 600 to 500 mb). While it's unlikely we realize the full magnitude of the 30 to 40+ kt winds that far up in the layer, the increased momentum within the mixed layer could still push surface winds a few mph higher than what NBM is currently forecasting. Still, even if winds were to verify on the upper end of guidance (ie NBM 90th percentile), we would still be just below red flag criteria for winds. Therefore, increased fire danger is likely with the dry conditions, but not anticipating serious fire weather concerns at this time.

The surface low pressure and it's associated cold front will eventually through the state Saturday night into Sunday. This will bring milder temperatures on Sunday, albeit still in the upper 40s north to low 60s south. There is a weak signal for some light precipitation over northern Iowa on Sunday morning, as low-level lapse rates steepen behind the front and a very shallow layer of instability develops. While this will most likely develop as broad stratus given a dry sub-cloud layer, can't rule out a few sprinkles being squeezed out of the thin saturated layer on Sunday morning.

LONG TERM /MONDAY THROUGH THURSDAY/

Issued at 315 AM CDT Fri Mar 20 2026

Mild temperatures continue on Monday before thermal ridging begins to build in from the west again through the middle of next week. A zonal flow pattern aloft will have multiple waves of energy passing through it during the week. Should enough moisture be available to any of these, we could see some chances at precipitation develop through the week. That said, there is little agreement among guidance on any of these waves, so the forecast remains primarily dry through the first half of the week. A more prominent trough then passes through the northern US during the second half of next week toward the end of this forecast cycle, which models seem to be in better agreement on. That said, what this system means for our area still remains uncertain, so will continue to monitor through the coming days.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 610 AM CDT Fri Mar 20 2026

VFR conditions prevail through the period. Winds will steadily transition from westerly to northerly through the morning, then go light and variable overnight tonight. Brief LLWS possible for a few hours this morning at KALO, KDSM, and KOTM.

CLIMATE

Issued at 1231 PM CDT Thu Mar 19 2026

Forecast and Record Highs for Select Central Iowa Cities...

==================================================================== | Today | Saturday | Period | Forecast Record/ | Forecast Record/ | of City | High Year | High Year | Record ==================================================================== Des Moines 77 79/1938 85 86/1938 1878- Mason City 65 73/1934 78 81/1938 1903- Ottumwa 76 78/1938 82 86/1938 1923- Waterloo 68 75/1918 79 83/1938 1895- ====================================================================

DMX WATCHES/WARNINGS/ADVISORIES

None.