I didn’t see a thread that dealt with flooding in Ottawa, so I’ll just put this in under Random Conversations.
Ottawa got a very significant amount of rainfall during the afternoon and evening of July 1, 2026. The rate of rainfall exceeded the rate that infrastructure could handle – which led to uncontrolled over-land water flow and localized flooding.
But is it really so unprecedented?
Daily precipitation in Ottawa (over 40.0 mm) from
Weather Stats:
1992-Jul-17 – 54.2 mm
1992-Aug-04 – 46.6 mm
1995-Jun. 03 – 66.6 mm
1995-Oct-06 – 76.0 mm
1995-Oct-21 – 58.8 mm
1996-Nov-08 – 42.2 mm
1997-Feb-21 – 40.0 mm
2000-Jun-25 – 46.4 mm
2000-Nov-26 – 46.2 mm
2001-Jun-22 – 45.8 mm
2002-Jun-11 – 52.0 mm
2002-Jun-27 – 57.0 mm
2003-May-24 – 42.4 mm
2004-Sep-09 – 135.4 mm
2005-Apr-02 – 46.2 mm
2005-Jun-14 – 41.0 mm
2007-Jul-20 – 67.8 mm
2008-May-31 – 47.8 mm
2008-Oct-25 – 44.8 mm
2009-Jul-18 – 47.8 mm
2009-Jul-24 – 40.6 mm
2009-Jul-29 – 47.0 mm
2010-Aug-15 – 42.4 mm
2011-Jun-24 – 90.4 mm
2012-Sep-18 – 45.4 mm
2013-Jul-09 – 42.6 mm
2014-Jun-24 – 55.6 mm
2017-May-01 – 45.4 mm
2017-May-05 – 40.4 mm
2017-Jul-01 – 42.0 mm
2017-Jul-24 – 79.0 mm
2017-Oct-30 – 56.0 mm
2018-Jul-23 – 43.0 mm
2018-Jul-25 – 61.4 mm
2020-Jun-05 – 52.1 mm
2021-Oct-16 – 49.4 mm
2022-Aug-07 – 47.6 mm
2022-Aug-08 – 57.9 mm
2023-Aug-09 – 77 mm
2024-Jun-06 – 44.1 mm
2024-Aug-09 – 45.5 mm
2025-Oct-07 – 58.6 mm
2026-Jul-01 – 82.4 mm
Oddly, Weather Stats did not have an entry for 2023-Aug-09, so I used the official 77 mm from Environment Canada. The actual local rainfall may have been up to 100 mm. Despite Weather Stats not having an entry, I know that it rained on that date, because the media was full of the reports of flooding:
https://www.ctvnews.ca/ottawa/article/ot...six-hours-flooding-roads-and-properties/
https://www.cbc.ca/news/canada/ottawa/flooding-power-outages-ottawa-1.6932806
Also oddly, Google could not find me any news articles about flooding in Ottawa from the extreme rain from the remnants of Hurricane Frances on September 9, 2004. That was, it seems, the highest one-day rainfall amount Ottawa has received, at 135.4 mm. I must assume that that much rainfall led to flooding, as well.
So the Canada Day rain we just experienced was extreme, but it wasn’t unprecedented. That said, each of the above rainfalls seemed to have affected the city differently.