In June in the Napa Valley, you are sure to experience warm daytime weather and pleasantly cool nights. Although you will probably not see any rain during your visit, the nights are still likely to be cool, so you may want to bring a light sweater for the evening.
In June, the average temperature in Calistoga is 68 degrees, with an average high of 86, and an average low of 50 degrees. The average rainfall in Calistoga for June is 0.22 inches. In the town of Napa, the average temperature in June is 66 degrees, while the average high is 78 and the average low temperature is 51. The average rainfall for June is 0.3 inches.
In 2014, June saw some very hot days, with temperatures hitting 90 on seven days, and one day, reaching 100. What is great about the June weather, however, is that the temperature invariably cools down at night, and on the day the temperature hit 100 as a high, it cooled to 53 that night. In short, June has great weather and is a fantastic month to visit Napa Valley.