How this report works
The report combines two public data systems, each cited on every page it feeds. Lake stage and water temperature, where a station reports it, come from US Geological Survey monitoring stations through the modern USGS Water Data API. Current nearby air temperature comes from National Weather Service stations through api.weather.gov.
A hard four-lake boundary
Only Lake Winnebago, Lake Mendota, Lake Monona, and Big Green Lake have public report pages. Each has direct on-lake USGS instrumentation. The route allowlist is fixed at build time, and every other lake, state directory, alphabetical directory, and search URL returns not found without fetching conditions data.
Observed context, not an ice model
Water level, water temperature, and nearby air temperature can help explain what monitoring stations are observing. They do not measure ice thickness at the place a person intends to travel, and this report does not convert weather history into modeled inches or a travel recommendation.
Freshness and failure behavior
USGS observations older than 24 hours are omitted. National Weather Service observations older than three hours are treated as unavailable. When a source fails or an assigned gage goes quiet, the page shows no replacement estimate. Every report displays its retrieval time and links the exact station pages.
What this tool will never do
It will never state or imply that ice is safe. It will not estimate ice thickness, determine whether travel is appropriate, or substitute nearby station data for an on-site check. It will not create pages for uninstrumented lakes. Every published page links its USGS, NWS, and DNR sources.