While situated in a semi-arid valley, Kamloops has winters that are generally mild and very short with an occasional cold snap where temperatures can drop to around -30 °C (-22 °F) when arctic air floods over the Rocky Mountains into the interior.

Snow can occur from November to March, but most of it falls over a few weeks in December and January. Winter mean minimum temperature is -7.6 °C (20 °F) in January.

Perhaps surprisingly, considering that Kamloops is located at 50° latitude north, summers are quite hot with prevailing dry, and sunny weather. The average July maximum temperature is 28.3 °C (83 °F) and would be higher if not for occasional incursions of cool northerly airmasses.

In most years, one might confuse this city with any in southern California, as summer temperatures come close to or even exceed 40 °C (104 °F). Humidity is generally very low and nighttime temperatures are moderate. These hot, dry conditions make the forest fire threat favourable in the region.

Spring arrives very early, sometimes in February, due to mild air spilling over the coastal mountains from the Pacific Ocean. Fall is generally a pleasant and a mostly dry season.

Kamloops lies in the "rain shadow" leeward of the Coast Mountains and is biogeographically connected to similar semi-desert and desert areas in the Okanagan region, the Osoyoos area, and the central parts of Washington and Oregon state as well as intermontane areas of Nevada in the U.S.

These areas of relatively similar climate have many distinctive native plants and animals in common, such as Ponderosa pine (Pinus ponderosa), big sagebrush (Artemisia tridentata), prickly pear cactus (Opuntia fragilis in this case), rattlesnakes (Crotalus viridis), Black widow spiders and Lewis's Woodpecker.