(out with the) Old Data

Every decade Environment and Climate Change Canada (ECCC) re-calculates normals for the previous 30 years. Current (April 2022) normals are derived from the 30-year period between 1981 and 2010. A quick bit of mental math tells us we’re due for an update. The USA completed its update (see graphic) in only five months (May 2021) but ours is still in progress.

Annual average temperature change from the old 1981-2010 normals to the new 1991-2020 normals. With the exception of the north-central U.S., the entire country trended warmer” (from https://www.weather.gov/ict/newclimatenormals )

David Phillips, Senior Climatologist at the ECCC, reassures us that the new normals data will be released in the summer of 2022, for the period from 1991 to 2021. Phillips is “anxious to see how the updated set of data, which will include the warm decade 2011 to 2020, will change the normals.”

As gardeners we can expect the average last-frost dates and the probability charts to shift. As well, there will likely be changes to Canada’s Plant Hardiness Zone Maps. And, of course, we’ll need to adjust our expectations for the 2023 gardening season.