| Category | Toronto Island Rank | Definition |
|---|
| Hottest summer | 9 | the highest average afternoon temperature in June, July, and August. |
| Coldest winter | 72 | the lowest average night-time temperature in December, January, and February. |
| Coolest summer | 92 | the lowest average afternoon temperature in June, July and August. |
| Mildest winter | 26 | the highest average afternoon temperature in December, January and February. |
| Coldest spring | 75 | the lowest average daily temperature in March, April and May. |
| Coldest year-round | 80 | the lowest average of all daily temperatures for the year. |
| Warmest year-round | 21 | the highest average of all daily temperatures for the year. |
| Most freezing days | 76 | the greatest number of days annually with the lowest temperature at or below 0°C. |
| Fewest freezing days | 25 | the fewest number of days annually with the lowest temperature at or below 0 °C. |
| Most hot days (30°C or above) | 17 | the greatest number of days annually with a daily high temperature of 30°C or above. |
| Most cold days (-20°C or less) | 73 | the greatest number of days annually with a daily low temperature of -20°C or below. |
| Most hot and cold days | 66 | the greatest number of days annually with daily highs of 30°C or above and daily lows of -20°C or below. |
| Warmest spring | 26 | the highest average daily temperature in March, April and May. |
| Warmest fall | 21 | the highest average daily temperature in September, October and November. |
| Wettest city (rain and snow) | 69 | the greatest total annual rain and snow. |
| Driest city | 32 | the least amount of total annual rain and snow. |
| Snowiest city | 79 | the greatest total annual snowfall (cm). |
| Lowest snowfall | 22 | the least amount of total annual snowfall (cm). |
| Snowiest fall | 94 | the greatest total snowfall in September, October and November. |
| Snowiest spring | 80 | the greatest total snowfall in March, April and May. |
| Snowfall as a % of precipitation | 85 | the annual total snowfall (cm) as a % of annual total precipitation (mm). |
| Rainiest city | 58 | the greatest total annual rainfall (mm). |
| Most wet days | 66 | the greatest number of days annually with measurable precipitation at or above 0.2 mm. |
| Most very wet days (25 mm or more) | 58 | the greatest number of days annually with precipitation at or more than 25 mm. |
| Most dry days | 35 | the greatest number of days annually with no measurable precipitation. |
| Most snow days | 69 | the greatest number of days annually with measurable snowfall at or above 0.2 cm. |
| Fewest snow days | 32 | the fewest number of days annually with measurable snowfall at or above 0.2 cm. |
| Most heavy snowfall days (10 cm or more) | 74 | the greatest number of days annually with a snowfall at or above 10 cm. |
| Most huge snowfall days (25 cm or more) | 99 | the greatest number of days annually with a snowfall at or above 25 cm. |
| Longest snow cover season (days) | 82 | the greatest number of days annually with snow covering the ground to a depth of at least 1 cm. |
| Most deep snow cover days (10 cm or more) | 85 | the greatest number of days annually with snow covering the ground to a depth of at least 10 cm. |
| Greatest average snow depth January 31 | 84 | the deepest median daily snow depth on January 31. |
| Most freezing rain days | 61 | the greatest number of days annually with an occurrence of freezing rain or drizzle. |
| Most blowing snow days | 65 | the greatest number of days annually with an occurrence of blowing snow. |
| Most thunderstorm days | 13 | the greatest number of days annually with an occurrence of a thunderstorm. |
| Fewest thunderstorm days | 88 | the fewest number of days annually with an occurrence of a thunderstorm. |
| Foggiest city (days) | 51 | the greatest number of days annually with an occurrence of fog (fog, ice fog or freezing fog). |
| Fewest fog days | 51 | the fewest number of days annually with an occurrence of fog (fog, ice fog, or freezing fog). |
| Most smoke and haze days | 7 | the greatest number of days annually with an occurrence of smoke or haze. |
| Sunniest year-round | 32 | the greatest number of hours annually with sunshine. |
| Least sunshine year-round | 69 | the fewest number of hours annually with sunshine. |
| Sunniest winter | 50 | the greatest number of hours of sunshine in December, January and February. |
| Sunniest summer | 47 | the greatest number of hours of sunshine in June, July and August. |
| Sunniest spring | 43 | the greatest number of hours of sunshine in March, April and May. |
| Sunniest fall | 21 | the greatest number of hours of sunshine in September, October and November. |
| Most sunny days year-round | 33 | the greatest number of days annually with an occurrence of sunshine. |
| Fewest sunny days year-round | 68 | the fewest number of days annually with an occurrence of sunshine. |
| Most sunny days in cold months | 52 | the greatest number of days from November through March inclusive with an occurrence of sunshine. |
| Most sunny days in warm months | 38 | the greatest number of days from May through September inclusive with an occurrence of sunshine. |
| Most heating degree-days | 77 | the greatest number of heating degree-days annually (accumulated average daily temperature below 18°C). |
| Most cooling degree-days | 9 | the greatest number of cooling degree-days annually (accumulated average daily temperature above 18°C). |
| Most growing degree-days | 14 | the greatest number of growing degree-days annually (accumulated average daily temperature above 5°C). |
| Highest average pressure | 21 | the highest hourly average sea level pressure (kPa) annually. |
| Lowest average pressure | 64 | the lowest hourly average sea level pressure (kPa) annually. |
| Greatest average pressure difference | 68 | the greatest difference between highest and lowest monthly average sea level pressure (kPa). |
| Most hours with low visibility | 57 | the greatest number of hours per year where the visibility is less than 1 km. |
| Clearest skies year-round | 36 | the greatest number of hours annually with total cloud amount between 0 and 2 tenths. |
| Cloudiest skies year-round | 36 | the greatest number of hours annually with total cloud amount between 8 and 10 tenths. |
| Most clear skies in summer | 28 | the greatest number of hours in June, July and August with total cloud amount between 0 and 2 tenths. |
| Windiest city year-round | 32 | the highest average hourly wind speed (km/h) annually. |
| Lightest wind speed year-round | 51 | the lowest average hourly wind speed (km/h) annually. |
| Windiest winter | 26 | the highest average hourly wind speed (km/h) in December, January and February. |
| Windiest summer | 41 | the highest average hourly wind speed (km/h) in June, July and August. |
| Most days with light wind (5 km/h or less) | 49 | the greatest number of days with at least one hour's wind speed at or less than 5 km/h. |
| Most windy days (40 km/h or more) | 19 | the greatest number of days annually with at least one hour's wind speed above 40 km/h. |
| Extreme wind chill | 59 | the highest wind chill in the period between 1952 and 2000. |
| Most high wind chill days (-30 or less) | 58 | the greatest number of days with an occurrence of wind chill less than -30. |
| Humidex days at or above 30 | 9 | the greatest number of days annually with humidex at or above 30. |
| High humidex days at or above 35 | 5 | the greatest number of days annually with humidex at or above 35. |
| Most humid summer city | 15 | the highest average hourly vapour pressure (kPa) in June, July and August. |
| Driest winter air | 60 | the lowest average hourly vapour pressure (kPa) in December, January and February. |
| Driest summer air | 68 | the lowest average hourly vapour pressure (kPa) in June, July and August. |