The US winter canola production and acreage have increased exponentially since 1990s due to increased demand for human consumption as oil and as a promising source of biodiesel feedstock. However, frost and winter kill are the major limitation of winter canola adoption in the US. Canola tolerance to cold and heat were assessed by studying percent pollen viability (PV), in-vitro percent pollen germination (PG) and growth of pollen tube length (PTL) for twelve field-grown cultivars. Freshly collected pollen from all cultivars were incubated at a constant temperature ranging from 10 to 30 °C at 5°C interval for 24 h to determine PG, and PTL. A bi-linear model best described the temperature response functions of PG and PTL. Canola cultivars showed significant variability for PV (61 to 90%), PG (29 to 48%), and PTL (525 to 1025 µm). The cardinal temperatures, T_min, T_opt, and T_max, averaged across cultivars, were 7.6, 23.6, and 32.8 °C for PG and 25.0, 33.3 and 5.4 °C for PTL, respectively. Maximum variability was observed for T_min; 4.3 to 9.75, PG and 1.9 to 7.3, PTL. Maximum PG was moderately correlated with PV (R² = 0.46). Principal component analysis (PCA) effectively distinguished between cold and heat tolerance and discriminated canola cultivars into tolerant, moderately tolerant, moderately susceptible and susceptible to cold and heat. PCA also revealed that maximum percentage pollen germination and maximum tube growth, T_min, and T_opt of both PG and PTL were the most important factors in determining cold tolerance whereas T_max of PG and PTL and the maximum pollen germination and tube growth were more responsible in separating the cultivars for heat tolerance. The identified cold- and heat-tolerant cultivars may be useful in canola breeding programs to develop cultivars suitable for a niche environment.