textproduct: Des Moines

KEY MESSAGES

- Do not burn today! Critical fire weather conditions/Red Flag Warning until mid-evening.

- Warmer Sunday into Monday with near record highs possible in a few places Monday. Elevated fire weather conditions possible in portions of Iowa Monday.

- Storm potential Monday night over north central/northeastern Iowa with large hail the main threat.

- Turning cooler Tuesday with breezy winds, then on and off precipitation chances remainder of the week.

SHORT TERM /THROUGH MONDAY/

Issued at 205 PM CDT Sat Mar 28 2026

Breezy winds from the south or south-southwest prevail early this afternoon gusting between 20 and 35 mph as surface high pressure departs Iowa into the Ohio Valley and low pressure develops over the central Rockies tightening the pressure gradient over the state. These winds have aided entraining drier air to the surface with single digit dewpoints in northwest Iowa. With reliable relative humidity values in the teens and these winds, the critical fire weather conditions are present. The patches of clouds from earlier today have largely thinned out over southern Iowa and moved out of north central Iowa leaving good viewing of any hotspots from fire. Shortwave IR imagery shows just a handful of fires - significantly less than last weekend. Winds will diminish this evening as the nocturnal boundary layer develops and relative humidity values begin their recovery to allow the Red Flag Warning to end mid-evening. Part of this recovery will be driven by low level warm air advection, which will draw higher dewpoints into Iowa as surface winds remain around 10 to 15 mph through daybreak Sunday. While Sunday will be warmer with highs well into the 70s, winds not as strong and higher dewpoints and resultant minimum relative humidity values in the 30 percent range will mitigate a critical fire weather day with Grassland Fire Danger Index (GFDI) mainly peaking in the high category (level 3 out of a max of 5).

The low pressure over the Rockies will slowly drift eastward along an east-west boundary, which will be north of the state on Monday. With Iowa in the warm sector and 900mb temperature change from Sunday to Monday of almost 10 degrees Celsius, will see highs shoot well into the 70s and the 80s. For a few places in Iowa, this will push highs to near record levels (see Climate section below). While dewpoints will be higher, these higher temperatures and slightly more breezy winds do kick the GFDI into the very high category in southern and parts of western Iowa. So, while not critical, it could be an elevated fire weather day.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/

Issued at 205 PM CDT Sat Mar 28 2026

As the sun sets Monday evening, will be monitoring for possible storm develop in the vicinity of the east-west boundary as theta-e advection pushes into it overnight. The low level jet will be increasing to between 35 to 45 knots with an environment characterized by MUCAPEs over 1000 J/kg, effective shear of 30ish knots, and 3-6km lapse rates of 8C/km. Models are quite diverse in their handling and there is limited convective allowing model (CAM) guidance at this range (e.g. RRFS, MPAS), but it seems somewhere over north central into northeastern Iowa may be the storm genesis region. Forecast soundings point to elevated storms, which would pose a risk of large hail. This seems to be the main risk despite favorable downdraft CAPE values over 1000 J/kg due to expected high cloud bases and more stable low levels with lapse rates around 5 C/km.

As a northern stream shortwave trough pushes down from the Canadian prairies into the far northern states, this will give the surface low a nudge eastward and drag the boundary into the state as a cold front on Tuesday. There may be a brief window in our far southeastern forecast area (e.g. Ottumwa, Centerville) for a few storms along this front, but the higher risk will likely be southeast of Iowa. Winds will be breezy behind the front with highs lower by nearly 30 degrees in northwest Iowa to 5 to 10 degrees lower in southeast Iowa. While this front is moving through our region, the next, weak shortwave trough will be coming onshore over California and moving quickly eastward reaching our region by Wednesday night into Thursday morning. While Gulf moisture will be lifted ahead of this wave toward Iowa, it looks to be limited and more shunted to the east. The limited moisture will still be sufficient for precipitation over at least southern Iowa sometime later Wednesday or Thursday with the broad time window due to uncertainty. While much of this will be in the form of liquid, cannot fully rule out wet snowflakes mixed in on the northern edge of the eventual precipitation shield. A more amplified trough pushes towards the region late next week into next weekend, which should bring back rain chances and perhaps instability for storm potential Friday and/or Saturday.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1054 PM CDT Sat Mar 28 2026

VFR conditions will prevail, a SCT deck of 4kft cigs will move across the state tonight. Southerly flow continues tomorrow with gusts over 20kts in the south. A BKN deck will form across southern Iowa, affecting mostly OTM after 18z.

CLIMATE

Issued at 205 PM CDT Sat Mar 28 2026

Forecast and Record High Temperatures for Select Central Iowa Cities...

============================================= | Monday | Period | Forecast Record/ | of City | High Year | Record ============================================= Des Moines 83 83/1968 1878- Mason City 79 78/1967 1903- Ottumwa 84 83/1967 1923- Waterloo 79 84/1967 1895- =============================================

DMX WATCHES/WARNINGS/ADVISORIES

None.