Climate observations are derived from two sources of data. The first are Daily Climate Stations producing one or two observations per day of temperature, precipitation. The second are hourly stations that typically produce more weather elements e.g. wind or snow on ground.

The Air Quality Health Index (AQHI) is a scale designed to help quantify the quality of the air in a certain region on a scale from 1 to 10. When the amount of air pollution is very high, the number is reported as 10+. It also includes a category that describes the health risk associated with the index reading (e.g. Low, Moderate, High, or Very High Health Risk). The AQHI is calculated based on the relative risks of a combination of common air pollutants that are known to harm human health, including ground-level ozone, particulate matter, and nitrogen dioxide. The AQHI formulation captures only the short term or acute health risk (exposure of hour or days at a maximum). The formulation of the AQHI may change over time to reflect new understanding associated with air pollution health effects. The AQHI is calculated from data observed in real time, without being verified (quality control).

The Air Quality Health Index (AQHI) is a scale designed to help quantify the quality of the air in a certain region on a scale from 1 to 10. When the amount of air pollution is very high, the number is reported as 10+. It also includes a category that describes the health risk associated with the index reading (e.g. Low, Moderate, High, or Very High Health Risk). The AQHI is calculated based on the relative risks of a combination of common air pollutants that are known to harm human health, including ground-level ozone, particulate matter, and nitrogen dioxide. The AQHI formulation captures only the short term or acute health risk (exposure of hour or days at a maximum). The formulation of the AQHI may change over time to reflect new understanding associated with air pollution health effects. The AQHI is calculated from data observed in real time, without being verified (quality control).

Current conditions and forecasts for selected Canadian cities. Raw XML data are used to generate each city page on the Environment Canada web site https://www.weather.gc.ca/.

The High Resolution Deterministic Land Prediction System (HRDLPS) produces high-resolution medium-range forecasts of land surface, subsurface variables, and of near-surface atmospheric variables (1.5 m temperature and dewpoint, 10 m wind). HRDLPS is initialized with analysis and trial fields provided by the Canadian Land Data Assimilation System of the National Surface and River Prediction System (CaLDAS-NSRPS). The system is then driven with atmospheric forecasts provided by the HRDPS over the first two days of integration and by the GDPS over the next four days. Predictions are performed twice a day. The system runs on a grid with a 2.5 km horizontal spacing covering Canada and part of the USA.

Daily climate observations are derived from two sources of data. The first are Daily Climate Stations producing one or two observations per day of temperature, precipitation. The second are hourly stations that typically produce more weather elements e.g. wind or snow on ground. Only a subset of the total stations is shown due to size limitations. The criteria for station selection are listed as below. The priorities for inclusion are as follows: (1) Station is currently operational, (2) Stations with long periods of record, (3) Stations that are co-located with the categories above and supplement the period of record.

HREPA is part of the NSRPS (National Surface and River Prediction System) experimental system dependent on two other systems. It uses surface station observations and radar QPEs pre-processed by HRDPA and disturbed trial fields generated by the Canadian Land Data Assimilation System (CaLDAS). HREPA produces four precipitation analyses per day on 6-hour accumulations valid at synoptic times (00, 06, 12, and 18 UTC). Each analysis set contains 24 members plus the control member. A quality index (confidence index) is also available on the same grid as the precipitation fields. Finally, two percentiles, 25th and 75th, estimated on these sets are also provided for each synoptic hour. Currently, there is only a high-resolution version of the system, whose domain covers Canada and the northern United States with a horizontal resolution of about 2.5km.

WCPS-coupled forecast is the component in the Water Cycle Prediction System (WCPS) that provides the coupled atmosphere-ocean-sea ice forecasts at a 1km resolution (0.008 x 0.008 degree) over the Great Lakes, St. Lawrence River and the Gulf of St. Lawrence. It launches 4 times a day at 00, 06, 12, and 18 UTC and produces 84 hours forecast, based on the atmospheric model GEM, coupled with the ocean-ice model NEMO-CICE. The products from WCPS-coupled forecasts are (1) GEM : surface air temperatures, surface wind velocities, and surface runoff (2) NEMO-CICE : variety of lake/ocean sea ice variables, for example, lake levels and temperatures. They are designed to help forecasters issuing bulletins and warnings in ice-infestested waters for navigation, water level alert, emergency response, Search and Rescue, and CIS Sea Ice forecast.

Radar coverage is provided to dynamically display the zones covered by the radars every 6 minutes, and to provide information on the availability (or not) of the contributing radars as well as on the areas of overlap.

A station is a site on a river or lake where water quantity (water level and flow) are collected and recorded.