# description
Public row contract for the derived base-50°F GDD data product.

# properties.zcta5.description
Five-character U.S. Census ZIP Code Tabulation Area code; this is not a USPS delivery-area boundary.

# properties.state_fips.description
Two-character state FIPS code assigned from the county containing the largest share of ZCTA land area.

# properties.state_code.description
USPS-style two-letter state or territory abbreviation for grouping only.

# properties.centroid_latitude_degrees.description
Representative latitude from the Census ZCTA Gazetteer.

# properties.centroid_longitude_degrees.description
Representative longitude from the Census ZCTA Gazetteer.

# properties.gdd_base_f.description
Base temperature subtracted from each daily mean; fixed at 50°F for this release.

# properties.accumulation_start_date.description
Calendar date at which annual GDD accumulation begins, always January 1 of source_year.

# properties.observation_start_date.description
First NOAA observation date with both TMAX and TMIN at the selected station.

# properties.observation_end_date.description
Last NOAA observation date with both TMAX and TMIN at the selected station.

# properties.days_with_observations.description
Count of source-year days with both TMAX and TMIN used in the accumulation.

# properties.cumulative_gdd_f_degree_days.description
Sum of max(0, (TMAX°F + TMIN°F) / 2 - 50°F) over available observation days.

# properties.station_id.description
GHCN-Daily station identifier selected for this ZCTA.

# properties.station_distance_km.description
Haversine distance from the Census ZCTA representative point to the selected station.

# properties.fallback_rank.description
Selected station rank by distance; 1 is the nearest candidate and values above 1 are fallbacks.

# properties.station_candidate_count.description
Maximum number of nearest active stations considered by the release pipeline.

# properties.freshness_status.description
fresh, stale, or unavailable relative to freshness_max_lag_days at generation time.

# properties.freshness_age_days.description
Whole UTC days from observation_end_date to release generation; null when data are unavailable.

# properties.freshness_max_lag_days.description
Maximum accepted observation lag used by the release pipeline.

# properties.data_available.description
True when a fresh station record produced a GDD value for the ZCTA.

# properties.unavailable_reason.description
Machine-readable reason for a missing GDD value: no_recent_station_data or no_station_data.