Summary
Polymarket's Hong Kong temperature markets resolve on the Hong Kong Observatory HQ ("Absolute Daily Max (deg. C)" from the HKO Daily Extract, weather.gov.hk) — an urban Kowloon station that is not an airport. The SDK's observation path (exact_fetch_observations / daily_extremes, keyed by ICAO airport code via IEM) cannot reach it.
Evidence
- IEM's entire Hong Kong network contains exactly one station —
VHHH (Chek Lap Kok airport):
https://mesonet.agron.iastate.edu/geojson/network/HK__ASOS.geojson → 1 feature, VHHH - Hong Kong.
- HKO HQ has no ICAO code, so it isn't in
STATIONS and can't be fetched via the ICAO/IEM path.
Impact
Any HK model/settlement built on the SDK has to proxy to VHHH, which differs systematically from the true resolution station:
- HKO HQ = dense urban Kowloon (heat-island), typically warmer;
- VHHH = island airport ~30 km west, maritime / cooler.
So a VHHH-based daily-max is the wrong target for HK settlement (different mean and variance). In a 51-city Polymarket backtest, Hong Kong was the only city whose actual resolution station could not be reached from IEM — every other city resolves on an airport ICAO that IEM carries.
Suggested fix
Add a Hong Kong Observatory data source (HKO Open Data API / weather.gov.hk Daily Extract) for the HK resolution station — and, more generally, support non-airport, national-met-service resolution stations (a few markets resolve on met-service HQs rather than airports). At minimum, flag in the catalog that HK has no IEM-reachable settlement station so callers don't silently proxy to VHHH.
Found while building international Polymarket daily-max backtests on the SDK (mostlyrightmd 1.3.1).
Summary
Polymarket's Hong Kong temperature markets resolve on the Hong Kong Observatory HQ ("Absolute Daily Max (deg. C)" from the HKO Daily Extract,
weather.gov.hk) — an urban Kowloon station that is not an airport. The SDK's observation path (exact_fetch_observations/daily_extremes, keyed by ICAO airport code via IEM) cannot reach it.Evidence
VHHH(Chek Lap Kok airport):https://mesonet.agron.iastate.edu/geojson/network/HK__ASOS.geojson→ 1 feature,VHHH - Hong Kong.STATIONSand can't be fetched via the ICAO/IEM path.Impact
Any HK model/settlement built on the SDK has to proxy to VHHH, which differs systematically from the true resolution station:
So a VHHH-based daily-max is the wrong target for HK settlement (different mean and variance). In a 51-city Polymarket backtest, Hong Kong was the only city whose actual resolution station could not be reached from IEM — every other city resolves on an airport ICAO that IEM carries.
Suggested fix
Add a Hong Kong Observatory data source (HKO Open Data API /
weather.gov.hkDaily Extract) for the HK resolution station — and, more generally, support non-airport, national-met-service resolution stations (a few markets resolve on met-service HQs rather than airports). At minimum, flag in the catalog that HK has no IEM-reachable settlement station so callers don't silently proxy to VHHH.Found while building international Polymarket daily-max backtests on the SDK (mostlyrightmd 1.3.1).