Gilbert Marine

Local Weather

May to October weather for Brockville, Ontario, in half-month steps (days 1–15 and 16 through the end of the month). Air, precipitation, and wet days use nearby Brockville Climate observations, about 6 km away (climate ID 6100970). Water temperature is the St. Lawrence surface at Ogdensburg, about 20 km east.

• Each tile is one half-month from May through October. Early is days 1–15. Late is day 16 through the end of the month. Every tile shows a value.
• Air temperature, precipitation, and wet-day percentage are 2021–2025 daily averages from Environment and Climate Change Canada, Brockville Climate (climate ID 6100970). High and low are the average of each year’s half-month mean, so each year counts equally. A year is included for a variable only when that half-month was observed on at least 80% of its days. Precipitation is the mean of each included year’s half-month total; missing days are not filled in. A wet day has at least 0.2 mm, among precipitation observations in the years included for that half-month. Days flagged missing are left out.
• Temperature and precipitation leave out early June 2021 (6 of 15 days) and early July 2024 (8 of 15 days). Missing days in an included half-month are not filled in. The largest gap in an included half-month is 2 days, in late June 2021 and late July 2024.
• Precipitation is liquid equivalent (rain plus the water in any snow), in millimetres per half-month.
• Sunshine is not biweekly. Brockville Climate does not publish bright sunshine, and the 1991–2020 normals do not include that row. Each month’s existing normal is repeated on both of that month’s tiles. Those hours are 1981–2010 normals from Ottawa Macdonald-Cartier International Airport (climate ID 6106000), about 80 km north, not a 2021–2025 average.
• Surface water temperature is the mean of hourly readings at NOAA CO-OPS station 8311030 (Ogdensburg, NY), on the St. Lawrence about 20 km east of Brockville, in local standard time. Each year counts equally. A year is included only when every May–October half-month has a reading for at least 80% of its hours. The years are 2010, 2012, 2015–2017, 2019–2021, and 2025. Left out: 2011 (June is empty and late May has 110 of 384 hours), 2013 (late June has 273 of 360 hours), 2014 (early May has 14 of 360 hours), 2018 (early May has 129 of 360 hours), 2022 (early May and October have no readings, and the series ends 28 September), 2023 (no readings), and 2024 (no readings until late August). In the years that are included, the largest hole is late October 2015, with 337 of 384 hours.
• Tile temperatures are rounded to the nearest degree.

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