How Splashtemp measures water temperature
Updated Wednesday, October 14 from Splashtemp data. Rebuilt daily.
Splashtemp is a Canadian initiative that brings public pool swim times and water temperatures into one place. We never invent a temperature: every number is either measured or a clearly labelled estimate.
Measured temperatures
Lake, river and ocean readings come from government monitoring stations. 543 stations currently have readings, and 506 reported in the last 7 days. We show the latest reading with its time and source, and keep it as published. Most real-time readings are provisional.
- Alberta Environment and Protected Areas – Alberta River Basins (rivers.alberta.ca) environmental data stations
- Environment and Climate Change Canada – Water Survey of Canada real-time hydrometric data
- City of Calgary – Watershed Surface Water Quality Data (Open Calgary y8as-bmzj)
- NOAA National Data Buoy Center (realtime2) – incl. Environment and Climate Change Canada / DFO MEDS moored buoys
- Province bot sensor finds (various operators; see each station)
- Fisheries and Oceans Canada – AZMP/IML Viking buoys (St. Lawrence Global Observatory ERDDAP)
Estimated temperatures
Where there is no sensor, Splashtemp may show an estimate, marked “Estimated” with a confidence level and a range. Basis: Observed daily mean air temperature (Environment and Climate Change Canada / MSC climate stations) smoothed over recent weeks, calibrated against Splashtemp's measured lake and river sensors.
In hold-out tests, typical error was about ±1.59°C for lakes (31 sensors, 2,400 sensor-days) and ±2.57°C for rivers (300 sensors, 20,314 sensor-days). A river-network model pilot (Alberta and BC) tested at ±0.77°C over 2,195 days at 13 sensors.
Today the map has 8,390 estimates. We don’t publish an estimate when the water is likely ice-covered (408), when there is no nearby weather data (3,704), or when the inputs are stale (33).
Pool temperatures and schedules
Pool water temperatures are shown only when the operator publishes them, and are labelled as the operator’s figure. Swim times come from official schedules and open-data feeds, are refreshed daily, and link to their source. Always confirm with the pool.