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Data staleness — when to re-check zipradar before making a decision
zipradar timestamps every page. The data is as fresh as the upstream regulator publishes — which varies wildly by dataset. Here's when to trust the snapshot and when to verify direct.
Published 2026-04-25 · Last reviewed 2026-04-25 · methodology
Refresh cadence by dataset
Hourly: AirNow real-time AQI. Always within 1 hour of measurement.
Daily: County recorder deed filings (most major counties). Within 24 hours of recording.
Weekly: FBI UCR rolling uploads. Latest week's data lands ~5-7 days after the agency files it.
Quarterly: EPA SDWIS, FEMA NFHL, EPA LCRR (lead). New violations + map revisions process every 90 days.
Annual: NCES CCD school data (released following October for prior school year). 12-18 months lag.
Annual: County assessor reassessments (most jurisdictions). Tax bills typically generated November.
Decadal+: EPA Radon Map (1993 baseline). Newer state radon programs supplement.
When zipradar's snapshot is good enough
Browsing neighborhoods, narrowing search: any-time freshness fine.
Initial assessment of flood/wildfire/water risk: quarterly is plenty.
Choosing between metros: schools/property tax annual is fine.
Crime trend reading: weekly UCR is fresh enough to spot direction.
When to verify with the primary source
Closing on a house this week: re-check FEMA NFHL at fema.gov for your specific address (NEW LOMAs may have been issued).
Pulling permit for major renovation: re-check zoning at the planning department TODAY (rezonings happen).
Filing flood insurance claim: today's NFIP policy form is the truth, not zipradar's quarterly snapshot.
Disputing a tax assessment: pull the current bill from the assessor directly.
Health emergency / outdoor activity in wildfire season: airnow.gov real-time is the source, not zipradar's hourly cache.
How zipradar flags staleness
Every page shows 'Last verified YYYY-MM-DD' — that's the federation refresh, not the upstream source's last update.
Where the upstream regulator hasn't published recent data, we say so explicitly (don't silently serve old data).
Methodology page documents the federation refresh schedule per dataset.
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