About the data

Primary source

Real-time observations come from the NOAA National Data Buoy Center (NDBC). Alaska Buoys ingests NDBC's active station inventory and standard meteorological real-time files (roughly 45 days of recent observations per station). We convert every timestamp to UTC internally and display Alaska local time by default.

Freshness

• Current — observation within the last 90 minutes.
• Delayed — 91 minutes to 6 hours.
• Stale — older than 6 hours.
• No data — no recent valid observation.

Missing values

NDBC uses sentinel values (like MM, 999.0, or 99.00) for missing readings. We render these as em dashes — never as zero. Zero is a real, valid measurement we preserve.

Terminology

Significant wave height

Average of the highest one-third of waves observed during a sampling period.

Dominant wave period

Period with the maximum wave energy.

Wind direction

Direction the wind is blowing from, in degrees clockwise from true north.

Pressure tendency

Change in atmospheric pressure over the last three hours.