SeaState US

A QGIS plugin that loads U.S. NOAA coastal data — tide-gauge water levels, tide predictions, and offshore buoy readings — as point layers on the map, and charts any of them as a time series.

Uses keyless public NOAA APIs — no account or token required.

Plotting a station's readings over time:

What it loads

Three layer types, each fetched for the current map view and date range:

Layer	What it is	Units	Source
Water levels	Measured water height at tide-gauge stations, every 6 minutes	feet (MLLW; IGLD on the Great Lakes)	NOAA CO-OPS
Tide predictions	Predicted daily high/low tides (not measured; coastal only)	feet, MLLW datum	NOAA CO-OPS
Ocean buoys	Offshore readings: wind, waves, air/water temperature, pressure	m, m/s, °C, hPa	NOAA NDBC

Water levels are observations; predictions are an astronomical calculation — different products, kept as separate layers. The NDBC live buoy feed spans only the most recent ~45 days.

Coverage: U.S. coasts, the Great Lakes, and territories (Puerto Rico, Guam, etc.). Coastal water levels use the MLLW tidal datum; Great Lakes use IGLD. Because the Great Lakes have no astronomical tides, tide predictions are coastal-only.

Using it

1. Add a basemap (Browser → XYZ Tiles → OpenStreetMap) and zoom to a U.S. coast.
2. Open the panel: Plugins → SeaState US → SeaState US.
3. Tick a layer to load it for the current view and date range; untick to remove it. Use Refresh for current view after moving the map or changing dates.
4. Plot over time charts the loaded data.

What gets plotted

Each loaded station or buoy becomes its own chart, stacked vertically in one scrollable window (they share the time axis). The value on each chart is:

• Water-level and prediction layers → water height (ft).
• Buoy layers → wave height (m), falling back to wind speed or water temperature when a buoy reports no waves.

So loading three tide gauges gives three separate water-level charts; loading a buoy adds a wave-height chart below them. Multiple buoy measurements are not combined on one axis — one metric per chart keeps units honest.

Install

Tested on QGIS 4.2 (macOS). Matplotlib — bundled with QGIS 4.2 — is required for the plot.

Copy or symlink the seastate/ directory into your QGIS profile plugins folder. On macOS:

ln -s /path/to/SeaState-US/seastate \
  "$HOME/Library/Application Support/QGIS/QGIS4/profiles/default/python/plugins/seastate"

Then enable SeaState US in Plugins → Manage and Install Plugins (tick "Show also experimental plugins" in that dialog's Settings tab).

Data sources

Source	Feed	Auth
CO-OPS tides & water levels	api.tidesandcurrents.noaa.gov (data + metadata APIs)	none
NDBC buoys	ndbc.noaa.gov active-stations XML + realtime2 text	none

NOAA's 6-minute water-level product is capped at 31 days per request; longer ranges are fetched in chunks automatically.

Limitations

• A very large request (wide view × long date range × several layers) can take a while. Fetching runs in the background so QGIS stays responsive, but the data will simply appear once each fetch completes.
• No CSV export (QGIS already exports any layer: right-click → Export → Save Features As → CSV).

Layout

seastate/
  metadata.txt          QGIS plugin metadata
  __init__.py           classFactory entry point
  seastate_plugin.py    plugin class + dock panel + load/plot logic
  layers.py             builds the QGIS point layers
  plot.py               Matplotlib time-series charts
  clients/
    coops.py            NOAA CO-OPS client
    ndbc.py             NOAA NDBC client
tests/
  console_test.py       run inside the QGIS Python Console

License

GPL-2.0-or-later.