Climate Trends and Variations Bulletin

Much of Canadian economic and social activity is climate dependent. Understanding how Canada’s climate is changing, in the context of global climate change, is important for developing adaptive responses. The Climate Trends and Variations Bulletin (CTVB) helps communicate to Canadians how Canada's climate has changed  over the recent past and longer, over the period for which Environment Canada has climate observations.

The CTVB describes climate variability through maps of current and past departures from the mean (the 30-year average 1961-1990) temperature and precipitation conditions, both seasonally and annually. This approach provides visualization of the extent to which temperature and precipitation vary above and below longer term average conditions. Maps are presented for each season and year. The data are then analyzed to see if there are detectable trends of longer terms against this backdrop of climate variability for Canada as a whole, and for 11 climate regions. This information is presented as graphs with trend lines to assess climate change over the period of record, starting in 1948 when nation-wide records became available.

The CTVB uses homogenized and adjusted station data for temperature and precipitation. These data have been adjusted to account for discontinuities in the data from non-climatic factors such as changes in observation methods or station location. See this brief description of the data and procedures used in the CTVB reports.

Over the past decade, precipitation monitoring technology has evolved and Environment and Climate Change Canada and its partners implemented a transition from manual observations to using automatic precipitation gauges. Extensive data integration is required to link the current precipitation observations to the long term historical manual observations. As of Autumn 2017, the update and reporting of historical adjusted precipitation trends and variations will be on temporary hiatus pending the extensive data reconciliation, and resumed thereafter. ECCC remains committed to providing credible climate data to inform adaptation decision making, while ensuring the necessary data reconciliation occurs as monitoring technology evolves.

In 2022, the CTVB celebrated 30 years of providing quality seasonal and annual climate information to Canadians. Read more: The Climate Trends and Variations Bulletin celebrates 30 years

If you encounter any problems, we would appreciate hearing [e-mail: btvc-ctvb@ec.gc.ca] about them so they can be corrected in a timely manner. Please note that notifications of the latest publication of the CTVB can be sent directly to your inbox when the bulletin is published on our website. For more information, please visit: CTVB – Subscribe.