Oshkosh, WI Weather

Key Messages

- Dense fog into early Friday morning. Dense Fog Advisory until 9 AM Friday much of northeast and east-central Wisconsin.

- Staying mild into the weekend, with high temperatures inland of Lake Michigan warming into the mid 60s to low 70s.

- Rain chances (20-40%) Saturday night over northern WI, and late Monday into Tuesday over central WI.

- Cooler start to next week, with highs mainly in the 50s.

Discussion

Issued at 1055 PM CDT Thu Oct 22 2026

Dense fog into early Friday morning...Lingering stratus from late afternoon has begun to build down and expand as dense fog with cooling of the evening. Expect dense fog overnight into early Friday morning, expanding farther to the west, before dissipating late in the morning. Dense Fog Advisory issued for most of northeast and east-central WI, including the Fox Valley. Only expecting patchy dense fog for central and north-central WI, so left those areas out of the advisory for now. Repeat performance of dense fog does not appear likely on Friday night as southerly flow begins to increase just off the surface ahead of cold front tied to strong low crossing Manitoba Canada. Lakeshore could still see patchy dense fog though.

Rain chances...Nothing to write home about, but there are a few times at least isolated light rain may occur in parts of the area. No widespread rain chances are in store though as strongest lift will remain tied into stronger low pressure systems tracking across Canada. Even so will be a few shortwave troughs/weak fronts shifting across the western Great Lakes at times, thus not a completely dry forecast. Most favored chances still in line for Saturday night into Sunday morning over the north (20-30%), then Monday night into Tuesday for especially central WI (20-40%). Beyond this, the weak fronts crossing the region will keep small chances of rain through late week with stronger cold front resulting in greater chances of rain late Wednesday into Thursday. Even with the more frequent chances rain seen compared to the relatively dry pattern of recent, overall rainfall amounts look light, under even a half inch for the entire time frame.

Next week temperatures...Cooling on the way, most notable Monday and Tuesday as highs reach the 50s for most, but may stay in the 40s far north. A bounce back occurs with highs in the 60s again ahead of the approaching front for Wednesday and Thursday. May turn cooler again late next week as we head toward the end of the month, but spread from 25th to 75th percentile on NBM is pretty high, so there are still uncertainties on temps by that time. Nighttime lows will be seasonable. Monday night lows do drop into the upper 20s to low 30s across the north, though little impacts are expected as the growing season has come to an end.

Aviation

for 06Z TAF Issuance Issued at 1248 AM CDT Fri Oct 23 2026

A low status deck over much of northeast WI has descended to the surface and is now creating a widespread area of dense fog for areas east of a IMT to DLL line. This includes ATW, GRB, and MTW. Patchy fog is also present further west, however, it is not expected to produce quite as significant an impact to vsbys. Expect lower vsby to persist through about 12-14z, with lingering stratus 14-16z this morning. VFR conditions should return to the entire area this afternoon. With high pressure overhead, winds will be light under 10 kts through the TAF period. Another round of fog is expected tomorrow night, however, it is not expected to be as widespread.

Grb Watches

Dense Fog Advisory until 9 AM CDT this morning for WIZ011>013- 019>022-031-037>040-048>050-073-074.