If you plan to visit Lviv, there is certainly no bad time but some times of the year are better than others. The climate here is considered “moderate continental” and there are rarely extremes in temperatures or overall climate. This is the Ukraine, however, and winters here are cold. The average temperature in January is 27 degrees, although it can get much colder. There can be periods of relative warmth, with the temperature reaching into the low 40's.
Most of the city’s annual average 26 inches of rain falls during the winter, as there are usually few rain showers during the summer months. During the summertime, the average daily temperature is about 65, although it can get into the 80's.
Many visitors head to Lviv in the spring and summertime when the winter’s rains have helped the city’s many trees thrive and add a green flourish to the city’s landscape. Thanks to the lack of rain, it’s an easy time to travel and, if you choose, walk around the city. It also likely will be sunny in the summer with an average of only 66 cloudy days a year here.