April is a transitional month between the cold and snow of winter and the warmth and thunderstorms of summer. Wide swings in the types of weather can still occur, as Arctic air can still come down from Canada to bring freezing temperatures, while storm systems can still push eastward from the Pacific Ocean.
Warm, moist air can flow northward from the Gulf of Mexico, helping to trigger thunderstorms, while warm, dry air sometimes pushes in from the desert Southwest, bringing warm temperatures and low humidities to the region.
The various snowstorms that come to Colorado make April the third-snowiest month of the year, behind November and March. One notable storm took place in 2001, bringing 10.0 inches to the former Stapleton International Airport, and strong winds brought blizzardlike conditions to much of Denver. Freezing temperatures are still possible throughout April, as the average date of the last freeze is not until May 5.
On the other hand, Denver averages over one day with thunderstorms. Occasionally, severe thunderstorms with tornadoes and hail may fall over Denver and eastern Colorado.
