Le Mars, IA 51031 Weather

Key Messages

- BREEZY CONDITIONS CONTINUE TONIGHT: Wind gusts slowly drop over the next few hours, except over the Buffalo Ridge where winds could gust to 30-35 mph through tonight. A second push of stronger winds arrives in south-central South Dakota near/just after sunrise. Gusts with this will increase to 35-40 mph for a brief period.

- COOLER WITH SCATTERED WEEKEND RAIN: A slow-moving front will bring increased clouds and occasional rain this weekend. Temperatures will be notably cooler (40s/50s) by Sunday.

- SIGNIFICANT RAINFALL LIKELY MONDAY-TUESDAY: A large multi-day system will bring widespread rain to start the new work week. Confidence in amounts over 1" through Tuesday morning remain high.

- ACTIVE WEATHER CONTINUES: A second fast moving system may bring rain chances back by Tuesday Night and Wednesday, with temperatures near seasonal normals.

Update

Issued at 931 PM CDT Fri Oct 23 2026

A warm and breezy late October evening continues across the area. Wind gusts will gradually drop off over the next few hours, though gusts will remain closer to 30-35 mph over the higher elevations of the Buffalo Ridge through the remainder of the night. A cold front will move into the area towards daybreak, and some stronger cold air advection behind this will bring another uptick in wind gusts in south-central South Dakota near and just after sunrise. Wind gusts with this will be 35-40 mph for a brief period, though could see one or two gusts up to 45 mph.

A couple of other things to note about this cold front and how it affects the forecast tonight: It will bring a quick drop in temperatures near and west of the James River towards sunrise, with temperatures falling to the low to middle 50s for morning lows. Secondly, there will be some rain showers that develop out of ahead of the front. Some elevated instability will lead to a few rumbles of thunder, but severe weather is not expected. This instability will wane through the day, so thunder chances will decrease as we go through the daytime hours Saturday. However, shower chances look to continue as more moisture moves into the area and saturates the column.

There will be some dry air nudging into our northwestern-most areas during the day Saturday, so this will lead to a relatively sharp gradient of where the rain starts and ends during the day Saturday. The better chances (30-60%) will be mainly near and east of a Brookings to Mitchell to Lake Andes line, with that line nudging eastward into the later afternoon and evening hours. The aforementioned cold front will also cause the high temperature to be in the morning for a large part of the area. The exception will be east of MN/IA Highway 60 where the cold front arrives last, and this is where highs will be reached during the usual mid-afternoon time frame. Adjusted hourly temperatures slightly for Saturday using the latest guidance, but no major changes in the overall temperature trend to note.

Discussion

Issued at 1218 PM CDT Fri Oct 23 2026

THIS AFTERNOON: Winds continue to increase early this afternoon with observed gusts between 30 and 45 mph. Temperatures continue to warm into the 70s, and potential for some highs in the 80s remain possible along and west of the James River valley. However, a persistent mid-upr cloud deck may limit the climb this afternoon. Out in western South Dakota, we're beginning to see the first signs of a frontal boundary forming that will gradually move eastward overnight. The fire danger remains very high this afternoon, especially for agricultural areas, please see separate discussion.

TONIGHT: An elongated upper trough stretching across the Rockies and into southern California will begin to stretch and split in two overnight. Northern energy tracking eastward across southern Canada will be strong enough to nudge the aforementioned surface boundary into the I-29 corridor by mid-mornign Saturday. Ahead of this boundary, convergence on a 40 knot LLJ and the arrival of a mid-lvl vorticity maxima should be enough to allow isolated to scattered showers to develop and and ahead of this boundary. MUCAPE may be as high as 300 J/KG after 3am, so have increased PotThunder to at least suggest isolated lightning strikes into mid-morning.

SATURDAY-SUNDAY: While northern stream energy moves eastward across Canada, a large upper trough will remain over the Four Corners region through the weekend. Overhead and closer to home, the aforementioned surface boundary will linger across the Tri-State area this weekend. This front, stacked on top by a low-lvl frontal zone, as well as somewhat persistent divergence from the right entrance region of an upper jet, will keep scattered rain chances and quite a bit of cloud cover through the area during the weekend. Now the degree of rain coverage is still up in the air, given somewhat diffuse and transient lift at times, but also some sub cloud dry air that could linger. So will continue to advertise a narrow stripe of low to mid-range PoPs that will fluctuate north and south with the movement of the low-lvl baroclinic zone.

Temperatures will be quite tricky on Saturday as the front bisecting the CWA could lead to a large temperature discrepancy from Huron to Storm Lake. 12Z guidance has trended downwards with highs slightly, so blended in short term guidance to account for trends the NBM may not have caught onto yet. There seems to be much more consistency in guidance that cooler air may sink further south behind the front for Sunday. With a persistent and cool northeast surface flow in the CWA, highs may struggle to break the 50s in portions of the CWA with the warmest highs near Highway 20.

MONDAY-TUESDAY: Slight discrepancies in medium range guidance on Thursday have resolved somewhat this morning. The large upper trough in the Four Corner begins to eject northeast late Sunday into Monday, and will begin to enhanced warm advection northward and increase the intensity of the low-lvl frontal zone through the CWA by Monday morning. We'll have to watch for any potential instability arrival, but fairly widespread moderate rain may begin to form Monday morning and gradually retreat northward as the upper trough enters the Plains.

Aviation

Issued at 1102 PM CDT Fri Oct 23 2026

Showers will increase in coverage through the morning hours on Saturday, with isolated thunderstorms possible. Any threat for thunder should end by the late morning hours, but scattered showers do look to continue at times through the end of the period. Some of the showers this morning will bring ceilings down to 2-3 kft, but otherwise VFR conditions are expected.

A cold front moves across the area today, which will turn winds to the northwest once it moves through. It will also bring a brief surge in wind gusts towards 35+ kts in south-central South Dakota immediately following the frontal passage near and just after sunrise.