Marine Weather and Tide Forecast for Hill City, SD

UPDATE
Issued at 1002 PM MDT Mon May 25 2026

No major changes to the forecast. Breezy southerly flow will develop tomorrow with advsy level gusts (45+ mph) possible over portions of the western SD plains. The limited coverage of these gusts will preclude any issuance of wind advisories at this time.
In addition to the gusty winds, very warm weather with highs in the upper 80s to upper 90s and minimum afternoon humidities ranging from 15 to 20 percent will lead to elevated to near critical fire weather conditions across much of the area with locally critical fire weather conditions possible where fuels are receptive.

DISCUSSION
(This Evening Through Monday)
Issued at 1203 PM MDT Mon May 25 2026

Current upper-air analysis and water vapor imagery depict large- scale ridging over the Rockies and troughing along the PAC NW coast.
A surface low remains positioned just off the coast. WV imagery indicates increased moisture over south-central SD, where isolated thunderstorms are possible this afternoon and evening, though conditions are more favorable farther east. Radar currently shows a few weak returns associated with possible developing convection over the northern Black Hills. Surface observations show temperatures mainly in the 80s with light and variable winds across the region.

As the trough propagates eastward, increased southerly/southeasterly low-level flow will bring higher dewpoints into the area this afternoon and evening, especially across south-central SD. HRRR guidance shows dewpoints rising into the 50s and lower 60s along with 0-6km bulk wind shear values of 25-35kts. Current CAM guidance continues to favor convective initiation over north-central NE before storms move into southeastern SD. However, an isolated thunderstorm or two can't be ruled out for south-central SD. Similar to the last couple of days, pop-up showers and an isolated thunderstorm or two may develop over and around the Black Hills through the afternoon and into the evening hours. High temperatures will range from the 80s to lower 90s today and persist through the week under continued ridging across the region.

By Tuesday afternoon, ensemble guidance shows the trough evolving into a cut-off low over OR/northern CA. This pattern will support a more active and unsettled weather regime across the region with near- daily thunderstorm chances through much of the week. Current SPC outlooks maintain general thunderstorms through Wednesday with no organized severe weather expected. This more active pattern is expected to continue through the weekend and into next week.

AVIATION
(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1039 PM MDT Mon May 25 2026

VFR conditions are expected through the forecast period.

Isolated showers or thunderstorms may develop in/near Black Hills during the heat of the day, but confidence in the storms reaching KRAP is very low.

Increasing southerly winds expected after 26/12-14z. Sustained winds around 15 to 25 knots with gusts nearing 35 knots. Winds should calm down around 27/01-03z.

FIRE WEATHER
Issued At 1203 PM MDT Mon May 25 2026

Even with green-up occurring across the region, relative humidity values over the next couple of days will fall into the mid-teens to low-20s across much of the area south of I-90. In addition to low RH values, gusty southerly/southeasterly winds are expected to develop Tuesday morning, leading to elevated fire weather conditions south of I-90.

UNR WATCHES/WARNINGS/ADVISORIES
SD...None.
WY...None.