Every number on North Weather comes from a named source. This page lists them, explains how we combine them and where their limits are.
| What you see | Source | How often we refresh |
|---|---|---|
| Current conditions | ECCC City Page Weather — the latest observation from the reporting station linked to the nearest forecast location | Hourly |
| Forecast: next 24 hours and days 1–7 | ECCC public forecast for the nearest forecast location | Hourly |
| Forecast: hours 25–48 and days 8–14; precipitation amounts, UV, cloud cover | WeatherAPI.com model data for the place's coordinates | Every few hours |
| Weather alerts | ECCC weather alerts, with their colour and text as issued | Every 10 min |
| Air Quality Health Index (AQHI) | ECCC AQHI observations and forecasts; pollutant estimates (PM2.5, ozone, NO₂) from WeatherAPI.com | Every 30 min |
| Radar and lightning | ECCC MSC GeoMet — 1 km radar composite with a new frame every 6 minutes, lightning density | Every 6 min |
| Satellite imagery | NASA Global Imagery Browse Services (GIBS) | Daily |
| Yesterday's weather, daily records, climate normals | ECCC climate data: daily climate observations, long-term climate extremes, 1981–2010 station normals | Daily / yearly |
| 30-day outlook, days 15–30 | Calculated from ECCC 1981–2010 normals for the nearest station; a seasonal estimate where no normals exist | With the forecast |
| Precipitation in the next two hours | Open-Meteo 15-minute nowcast | Every 15 min |
| Water temperatures | Open-Meteo marine data (satellite and model sea-surface analysis); NOAA GLERL GLSEA for the Great Lakes; nearby NOAA CO-OPS stations for some enclosed waters | Every 12 hours |
| Northern lights | NOAA Space Weather Prediction Center — Kp index and 3-day forecast | Every 20 min |
| Tropical storms and hurricanes | NOAA National Hurricane Center (positions, intensity, outlooks); Canadian watches and warnings come from the Canadian Hurricane Centre (ECCC) | Every 15 min |
| Sun, moon and meteor showers | Calculated with standard astronomical algorithms; eclipse dates from NASA's eclipse catalogue | — |
| World destinations | WeatherAPI.com forecasts; monthly climate tables from ERA5 reanalysis via Open-Meteo | Every 2 hours / yearly |
| U.S. city pages (for visitors from the United States) | WeatherAPI.com model forecasts for 2,080 U.S. cities with 25,000+ people, with Open-Meteo as a backup; no U.S. alerts, radar or air quality — official U.S. watches and warnings are on weather.gov | Every few hours |
| Postal code search | Statistics Canada 2021 Census Forward Sortation Area boundaries (the first three characters of a postal code), matched to our places by location | With each census |
| Your approximate area (home page and header) | A local copy of the MaxMind GeoLite2 City database — no outside service is contacted | Database replaced at least monthly |
| Places and coordinates | GeoNames geographical database (Canadian places; U.S. cities with 25,000+ people) | Occasionally |
| Maps | Esri basemaps, © OpenStreetMap contributors; precipitation layers on some maps from OpenWeatherMap | — |
"How often we refresh" is how often we check the source; a new number appears only when the source itself has updated.
Each place is matched to the nearest ECCC forecast location, and that location's official forecast is used for the next 24 hours and the first seven days. Current conditions come from the ECCC reporting station tied to that forecast location, which can be some distance away in rural and northern areas. WeatherAPI.com model data, computed for the place's own coordinates, extends the forecast to 14 days and adds values ECCC does not publish in its city forecasts, such as precipitation amounts in millimetres, the UV index by hour and cloud cover. If ECCC data is temporarily unavailable, the page shows the model forecast alone; if WeatherAPI.com is unavailable, it shows ECCC's seven days; if both are down, it falls back to Open-Meteo model data.
Weather alerts, the AQHI, radar and climate records are shown as ECCC publishes them. We do not change the content or intent of an alert. Very long alert texts may be shortened on the page, with a link to the complete alerts on weather.gc.ca.
Search matches place names with or without accents and understands common abbreviations such as St, Ste, Mt and Ft, so "st jerome" finds Saint-Jérôme. You can also type the first three characters of a postal code, such as M5V. Canada Post's complete postal code data is licensed, so for these areas we use Statistics Canada's census boundaries: an urban code opens the forecast for its community, and a rural code — one with a zero as the second character, such as K0A — lists the places inside that area. Statistics Canada draws these boundaries from the postal codes people reported in the census, so they are close to, but not always the same as, Canada Post's delivery areas.
The home page opens on your approximate area, looked up from your IP address in a local copy of the MaxMind GeoLite2 database. An IP address often places you only to within a city or region, so when the lookup is not precise enough we open Toronto rather than guess; the location button uses your device's position and is far more accurate. Visitors from the United States see the nearest U.S. city with 25,000 or more people. Those pages carry the forecast only: for official U.S. watches and warnings, use weather.gov. We keep anonymous daily counts of how these lookups turn out, with no IP addresses or locations, to check how well the database works for our visitors.
Temperatures are in degrees Celsius (a °F switch is in the header), wind in km/h, rain in millimetres, snow in centimetres, pressure in kilopascals and visibility in kilometres. Times are local to the place you are viewing. "Feels like" shows the humidex in warm, humid weather and the wind chill in cold, windy weather.
Spotted a wrong number or a place in the wrong spot? Tell us — include the page address and the time you saw it.