Monticello, IN Weather

Key Messages

- Dense fog will impacts portions of the area through late morning. An advisory is in effect.

- Otherwise, pleasant weather persists through the upcoming week with highs around 70, lows in the 40s, and no rain expected.

Discussion

Issued at 240 AM EDT Sat Oct 24 2026

Another day with fog as the only sensible weather concern. Latest satellite and surface obs show dense fog rapidly expanding across our eastern CWA thanks to another night of light easterly flow off Lake Erie and prime radiational cooling. High clouds that were in place earlier thanks to upstream trough have now largely dissipated for most of the area and see no reason why fog won't continue to expand and persist through the late morning as suggested by plethora of latest guidance. Only question is how far west and south it will build. With light E to even ESE flow, confidence is not high for our southwest zones. Latest satellite shows a rapid expansion to the NW but very little southward expansion. Issued a dense fog advisory but left off the far west and southern counties for now. Will continue to monitor obs and expand as necessary. Surface winds finally veer to the south tonight and more high clouds should limit fog potential (save perhaps for our extreme NE areas where Lake Erie could still be a factor).

Highs today a near carbon copy from yesterday given no thermal advection. Highs do creep up a few degrees Sun and Mon as very light southerly flow/minor WAA takes shape. A weak backdoor front then brings a brief return to cool easterly flow for Tue but WAA increases again for Wed and Thu as a decaying cold front approaches the region. This front looks to stall and wash out just to our NW with just some very low chances for light rain near Lake MI Thu into Fri. Better rain chances arrive over the weekend but there is still a high degree of spread regarding exact timing and amounts.

Aviation

Issued at 635 AM EDT Sat Oct 24 2026

Satellite imagery and sfc observations indicate continued westward migration of widespread LIFR cigs/vsbys. Earlier forecast thinking with best potential of dense fog east of KSBN has been amended to include a period of dense fog at KSBN in the 12-14Z timeframe. Very poor mixing in weak easterly low level regime will make improvements slow today, particular at KFWA where VFR conditions may not return until after 16Z. Otherwise for today into this evening, some mid/high clouds will likely drop southeast across southern Great Lakes as eastward migration of mid/upper level ridge axis allows for some warm advection forcing. Will have to monitor potential of some additional fog tonight, particularly in KFWA vicinity with similar synoptic pattern in place. The combination of low level flow veering light southerly tonight and the possibility of some high level cloudiness leads to somewhat low confidence at this forecast distance, but it is possible additional forecasts/amendments will need to be more aggressive with BR/FG mention at KFWA toward end of this valid period.

Iwx Watches

IN...Dense Fog Advisory until 10 AM EDT /9 AM CDT/ this morning for INZ005>009-014-015-017-018-023>027-032>034-103-104-116- 204-216. OH...Dense Fog Advisory until 10 AM EDT this morning for OHZ001-002- 004-005-015-016-024-025. MI...Dense Fog Advisory until 10 AM EDT this morning for MIZ078>081- 177-277. MARINE...None.