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Humidity is related to the amount of moisture or water vapour in the air. Although invisible, water vapour is always present in the atmosphere.

There are six time zones in Canada covering four and a half hours. From west to east these time zones are: Pacific, Mountain, Central, Eastern, Atlantic and Newfoundland. From the first Sunday in November to the second Sunday in March these zones are referred to as standard time zones, and may be abbreviated as PST, MST, CST, etc. From the second Sunday in March to the first Sunday in November most of Canada follows daylight saving time. During this summer period the time zones may be abbreviated as PDT, MDT, CDT, etc. The boundaries of the standard time zones are not necessarily the same as those of the corresponding daylight saving time zones. For example, the Mountain time zone includes a portion of northeastern British Columbia in the summer, but not during the winter (see maps below). Boundaries shift because some municipalities choose not to participate in daylight saving time. Similarly, Saskatchewan follows CST year-round and, as of 2020, Yukon follows PDT, also known as Yukon Standard Time, year-round.

Floods are primarily caused by naturally occurring changes in the height of rivers, lakes and oceans. According to Public Safety Canada, floods are the most common natural hazard in the country and among the costliest. Historic floods have occurred across Canada, with many of the worst happening on major river systems that pass through populated areas. Scientists predict that flooding linked to the impacts of climate change will increase as the 21st century progresses, particularly in coastal areas of the country.

Permafrost is ground remaining at or below 0°C continuously for at least two years. About 50 per cent of Canada is underlain by permafrost, mainly in the Arctic Archipelago, Yukon, Northwest Territories and Nunavut.

Winter occurs as the Earth's axis tilts away from the sun during the planet's annual rotation. The portion of the Earth that is furthest from the sun experiences winter, with weather that is colder than the other seasons. In the Northern Hemisphere, winter officially begins with the winter solstice, around 21 December, and ends at the spring equinox, around 21 March. Winter figures largely in Canada's climate, cultural experience and mythology. Every aspect of life in Canada is affected by winter, whether by heavy rains on the West Coast, isolation during the long Arctic winters, raging blizzards across the prairies or huge snowfalls in eastern Canada. Winter is reflected in Canadian art, literature, music, fashion, pastimes and attitudes.

​Vegetation regions are geographical areas characterized by distinct plant communities.