Communicating Research Findings and Supporting Planning

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Seasonal Anomaly Maps

The differences between average weather conditions that normally prevail at a given time of year and what is experienced is a critical link between people and climate. The normal, or expected, weather conditions for a month or season is known as the climatology for an area and plays a major role in defining the locale. Departures from normal conditions are experienced as unusual weather such as rainier or colder than normal periods or the opposite (drier or warmer). A simple and intuitive way to understand and depict how different observed conditions are from normal is to map average temperature and total precipitation departures from the long term climatology at observational weather stations. The results indicate spatial patterns and extents of warm/cold and wet/dry regions.

PCIC has constructed such maps for all months from 1900 onward using data collected within BC Ministry of Environment and Climate Change’s Climate Related Monitoring Pogram and assembled into the PCDS (link to PCDS data portal splash) . Monthly maps of maximum and minimum temperature departures as well as total precipitation departures are provided on a monthly average and a seasonal average basis (for the purpose of these maps, seasons are defined as SON for fall, DJF for winter, MAM for spring, and JJA for summer). To access these maps, use the following tool to select a year and season of interest and then click on “Get Maps”. You will be directed to a page showing the monthly climate anomaly maps along with the anomaly for the season if all maps for the selected season have been completed. These maps should provide a quick, informative look at anomalous weather in and surrounding the province that users can relate to conditions and impacts that they have observed. Data are updated at least twice monthly on the 4th of the month and the 16th as new data becomes available. All anomalies are presented relative to the 1971–2000 climate baseline.


All anomalies are presented relative to the 1971 – 2000 climate baseline. New monthly and seasonal maps will be released on an ongoing basis near the 15th of every month following the month of interest. For example, the map of anomalies for May will be generated and posted near June 15th.