British Columbia Precipitation, Normals vs Actuals, 2010–2014

Actual   Below normal   Above normal

This visualization shows monthly precipitation recorded at British Columbia weather stations from 2010 through 2014, inclusive. Note that the line on the graph has been interpolated using D3.

The actual precipitation data is compared with the historical normal precipitation for that weather station, as recorded in the period 1980 – 2010.

Usage notes

To more easily compare precipitation across different weather stations, check the Lock Y-axis checkbox. Uncheck it to scale the Y-axis based on the precipitation at each station.

Blue areas represent amounts of precipitation above seasonal normals. Red areas represent periods of below-average precipitation.


The historical and actual precipitation data were downloaded from Environment Canada (links below).

The stations were selected by first collecting those appearing with an asterisk in this list of BC weather stations. (An asterisk indicates a station meets UN WMO standards.) Actual daily historical data for these stations were then downloaded and collated by month.

In some cases, weather stations with identical names have been “replaced” in the Environment Canada data; for example, examine the effective dates for “Abbotsford A” in this list. In these cases, data files were stitched together to ensure continuous data.

In other cases, the data for a station were insufficiently complete; any stations with more than 10 days missing in a single month were rejected.

The historical and normal data for remaining stations were compiled into a single CSV file, which forms the basis for the visualization.


The BC geometry shapefile is adapted from Natural Earth's set of states and provinces, transformed using ogr2ogr and topojson. For an introduction to these tools (and mapping with D3), see Let's Make a Map.

Weather data from Environment Canada: actuals and normals.

Built with D3, topojson, and Bootstrap.


We'd be happy to hear your feedback. Please e-mail Frank Hangler at