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Data as of 2025-12-31
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Built 2026-10-19 (19 October 2026)

Ontario Threshold Days by Year (USW00024162)

14 fixed thresholds counted per year at Ontario (USW00024162): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Ontario Thresholds

  • Ontario: days with a maximum temperature at or above 30 C (86 F) in 28 years, most in 2021 with 97.
  • Ontario: days with a maximum temperature at or above 35 C (95 F) in 28 years, most in 2022 with 62.
  • Ontario: days with a maximum temperature at or above 90 F (32.2 C) in 28 years, most in 2017 with 81.
  • Ontario: days with a maximum temperature at or above 100 F (37.8 C) in 28 years, most in 2021 with 38.
  • 14 fixed thresholds have at least one qualifying day at Ontario.
28 years with a qualifying day
Days at or above 30 C (86 F) per year at Ontario Days per year at Ontario with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 97 in 2021. 02550751001998: 701999: 622000: 782001: 802002: 862003: 912004: 642005: 682006: 842007: 922008: 792009: 822010: 672011: 772012: 922013: 932014: 872015: 952016: 772017: 952018: 812019: 862020: 892021: 972022: 912023: 922024: 962025: 891998200120042007201020132016201920222025
Days per year at Ontario with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 97 in 2021.
Days at or above 30 C (86 F) per year at Ontario
YearDaysDecade average
19987066
19996266
20007880.4
20018080.4
20028680.4
20039180.4
20046480.4
20056880.4
20068480.4
20079280.4
20087980.4
20098280.4
20106785
20117785
20129285
20139385
20148785
20159585
20167785
20179585
20188185
20198685
20208992.3
20219792.3
20229192.3
20239292.3
20249692.3
20258992.3
First to last qualifying date each year at Ontario For each year, a bar from the first to the last day at Ontario meeting 30 C (86 F). 1998: 18 June 1998 to 17 September 19981999: 23 May 1999 to 23 September 19992000: 21 May 2000 to 18 September 20002001: 11 May 2001 to 24 September 20012002: 13 May 2002 to 15 September 20022003: 23 May 2003 to 2 October 20032004: 2 June 2004 to 11 September 20042005: 28 May 2005 to 8 September 20052006: 14 May 2006 to 13 September 20062007: 11 May 2007 to 15 September 20072008: 16 May 2008 to 1 October 20082009: 21 April 2009 to 26 September 20092010: 13 June 2010 to 2 October 20102011: 21 June 2011 to 1 October 20112012: 22 April 2012 to 19 September 20122013: 8 May 2013 to 16 September 20132014: 15 May 2014 to 24 September 20142015: 29 May 2015 to 10 October 20152016: 12 May 2016 to 30 September 20162017: 4 May 2017 to 13 September 20172018: 27 April 2018 to 8 September 20182019: 11 May 2019 to 15 September 20192020: 29 April 2020 to 2 October 20202021: 29 April 2021 to 27 September 20212022: 15 May 2022 to 28 September 20222023: 10 April 2023 to 25 September 20232024: 11 May 2024 to 28 September 20242025: 9 May 2025 to 20 September 20251998200220062010201420182022JanFebMarAprMayJunJulAugSepOctNovDec
For each year, a bar from the first to the last day at Ontario meeting 30 C (86 F).
First to last qualifying date each year at Ontario
YearFirst dateLast date
19981998-06-181998-09-17
19991999-05-231999-09-23
20002000-05-212000-09-18
20012001-05-112001-09-24
20022002-05-132002-09-15
20032003-05-232003-10-02
20042004-06-022004-09-11
20052005-05-282005-09-08
20062006-05-142006-09-13
20072007-05-112007-09-15
20082008-05-162008-10-01
20092009-04-212009-09-26
20102010-06-132010-10-02
20112011-06-212011-10-01
20122012-04-222012-09-19
20132013-05-082013-09-16
20142014-05-152014-09-24
20152015-05-292015-10-10
20162016-05-122016-09-30
20172017-05-042017-09-13
20182018-04-272018-09-08
20192019-05-112019-09-15
20202020-04-292020-10-02
20212021-04-292021-09-27
20222022-05-152022-09-28
20232023-04-102023-09-25
20242024-05-112024-09-28
20252025-05-092025-09-20

Every Fixed Threshold

Fixed thresholds at Ontario
ThresholdYears with a qualifying dayMost days in a yearYearLatest year days
30 C (86 F): Days2897202189
35 C (95 F): Days2862202236
40 C (104 F): Days191520212
90 F (32.2 C): Days2881201767
100 F (37.8 C): Days2838202110
110 F (43.3 C): Days4320021
0 C (32 F): Ice days (max284520136
0 C (32 F): Frost days (min281532013110
-10 C (14 F): Days with min2740201312
-20 C (-4 F): Days with min6920131
20 C (68 F): Tropical nights (min282920219
25 C (77 F): Days with min5220151
10 mm (0.39 in): Days with 10 mm or more rain271020175
25 mm (0.98 in): Days with 25 mm or more rain4120051

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1998.

Download the Data

  • Data for Ontario threshold days by year: CSV or JSON. Field meanings are on the data page.

Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-17 (17 October 2026). Threshold counts are computed by this site.

Data as of . Last revised (2025-12-31).