Ontario,
in motion.

A living map.
Real model data.

Particles follow actual model velocity fields. Lake Ontario uses NOAA’s native LOOFS mesh; the lower St. Lawrence uses ECCC OHPS and DFO STLE200 data through the St. Lawrence Global Observatory.

Publication

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Source checks

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Ontario source

NOAA LOOFS ↗

Ontario layer

Top model sigma layer · 64,453 native triangular cells

Ontario period

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Selected file

Source dataset ↗

River source

ECCC OHPS / SLGO ↗

River layer

Depth-averaged current, not a surface layer. Display sampled at approximately 600 m. No river temperature is supplied; blue is a neutral river colour.

River period

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Estuary source

DFO STLE200 / SLGO ↗

Estuary layer

Surface currents from Trois-Rivières to Les Escoumins, including modelled Saguenay waters. SLGO display grid sampled at approximately 0.75–0.9 km; this is coarser than the underlying model.

Estuary period

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Live & average views

Live shows the latest successfully published Ontario nowcast and the river/estuary forecasts nearest their source checks. Each source’s valid time is kept separately. The timeline changes Ontario’s field; the river remains at its separately displayed forecast time.

24-hour mean averages eastward and northward velocity components from nine fields, sampled every three hours. Ontario uses the preceding 24 hours of nowcasts. The river uses the first 24 hours of the available forecast. These source periods differ. Both are stated here and in the map controls. This is a sampled vector mean, not a long-term or seasonal climatology; opposing flows can cancel.

Complete shores, honest coverage

The complete water polygons preserve islands and connecting channels from Toronto through Montréal and into the estuary. Ontario currents remain inside the native model triangles. River cells are clipped to mapped water; unavailable vectors are never extrapolated across gaps.

Lake trails use continuous interpolation inside the native wet triangles, retaining the original vectors at triangle centres. This removes triangular drawing steps without adding model resolution or filling source gaps. Display method ↗

Coverage gaps

Ontario’s model stops near Kingston. The river model begins around Lac Saint-Louis / Montréal and continues toward Île aux Coudres. The overlapping STLE200 surface field extends coverage to Les Escoumins and into the Saguenay. Where these river fields overlap, the surface field is shown. Lake Simcoe is outside these government current products; parts of the upper river and Montréal’s north channels also lack retrieved vectors. Their shores remain visible. The broader outer estuary is supplemented by the independently dated STLE500 archive mean. Any experimental Simcoe response is separately identified.

Motion is accelerated for visibility. Government model estimates are not direct current measurements. Published source data are checked hourly. The open map rechecks published files every 15 minutes. Source outages retain validated, dated fields; status text identifies retained or overdue data. A failed source check is never labelled a successful live refresh.

Related temperature-film project

Lake Ontario: A Week in Motion ↗ has its own website and source repository. Its 25-second loop plays through 12–18 October 2026 UTC using hourly NOAA surface currents and temperatures. Velocity drives the trails; colour represents temperature on a fixed 12–16.5°C scale with labelled endpoint caps. A date clock follows the changing fields; a brief labelled replay transition restarts the week. Kingston–Brockville currents and temperatures are estimates: fixed 12–17 October flow forcing carries hourly lake-inlet temperatures with no heat exchange. River temperature assumptions ↗ · Hourly sources and colour scale ↗

Outer estuary archive

The broader estuary uses DFO POPS STLE500 surface vectors from 12 October 2026 00:00–17 October 2026 12:00 UTC, averaged from 23 six-hourly archived forecast fields. This fixed archive mean retains its own dates in both website modes; it is not labelled a current forecast or a 24-hour mean. STLE200 and the other existing products take priority where they already supply vectors. The STLE500 display fills only their missing cells, clipped to mapped water. Component orientation was checked against STLE200 in their overlap and against narrow-channel geometry; it is an empirical check, not observation-based validation.

Simcoe drainage and the divide

The static tributaries and Lake Simcoe catchment come from LSRCA open GIS. The dashed gold line is the shared Lake Huron / Lake Ontario basin boundary. Near the Oak Ridges Moraine, it separates Simcoe/Georgian Bay drainage from Lake Ontario drainage. Farther east, parts of the moraine's northern side reach the Trent system and ultimately Lake Ontario. Tributary lines are drainage geography; no current speeds are inferred for them.

Contains Information made available under Lake Simcoe Region Conservation Authority Open Data Licence v1.0. Contains information licensed under the Open Government Licence – Ontario.

Experimental Lake Simcoe response

A separately supplied unvalidated, depth-averaged wind response may be shown for 12 October 2026 00:00–17 October 2026 12:00 UTC. It is a rotating two-dimensional, barotropic model driven by observed wind over real bathymetry, not observed lake currents, a calibrated forecast or a government current product. The Atherley boundary is closed; exchange through the Narrows is not represented. Stratification and three-dimensional circulation are not resolved.

This optional field retains its own fixed period in both Live and 24-hour views. It supplies no water temperature. Simcoe-focused views use a fixed 0–5 cm/s colour scale; mixed regional views use the logarithmic 0–150+ cm/s scale. The displayed velocity values retain their original units and magnitudes. An in-frame experimental label remains visible wherever the field is shown.

Fixed period

No experimental dataset is included.

Method

The map remains shoreline only until a separately labelled experimental dataset is supplied.

Geography & inspiration

Complete water polygons: © OpenStreetMap contributors, ODbL, supplied through OpenFreeMap and © OpenMapTiles; island holes are retained. Canadian model data: Open Government Licence — Canada. Visual inspiration: the flowing map films of mapped.earth. This is an independent website; no generated imagery is used.

For exploration and education. Not for navigation.