seasons than summers and winters, and they feature varied weather with alternating periods of dry, sunny weather and rain. Many days in these seasons are sunny with pleasant rather than warm or cold temperatures. Nights are generally cool, but frosts are rare. Snow can fall in early spring or late fall but usually melt quickly after contact with the ground. At these changeable times of the year, temperature contrasts (up to in extreme cases) can occur within a short time frames due to rapidly changing air masses that sweep across the continent, often accompanied by high winds. Due to these airmass changes, temperatures of or above have been recorded as early as April 16 and as late as October 8. Conversely, temperatures of or below at night have been recorded as early as November 6 and as late as April 18. Snowfall has been reported as early as October 1 and as late as May 28. Toronto's weather is affected by the relative position of the polar jet stream and continental storm track, both of which pass over or near to the area with some frequency. This is determined by a number of complex global weather drivers, such as ENSO, NOA/AO Oscillations and the Polar vortex. There is no "dry season" as precipitation falls in all months with regularity (but mainly snow during the winter), but summer rains result mostly from thunderstorms, which make for higher average amounts as a general rule with occasional dry periods. February and March rank as the driest months on average. Annual average precipitation is . Cherry blossom trees bloom in Toronto during late April and early May. Winter and snowfall Despite being cold, extended snow-free periods occur in most winter seasons and precipitation can fall as rain with temperatures sometimes climbing above . Average winter snowfall is at the weather station in Downtown Toronto and at Toronto Pearson International Airport. The average January maximum / minimum is between in the city. There are usually a few colder periods where temperatures remain below and less frequently below at night (especially in the northern suburbs), with wind chills making it feel like . Due to its position on the northwest shore of Lake Ontario, Toronto is not a direct target of heavy, wind−whipped lake-effect snow squalls that hit other Great Lake cities on the south/east shorelines of the lakes, in areas where prevailing winds amplify lake