The proximity to a large body of water which is slow to react to seasonal temperature changes, combined with the modifying influences on frontal systems approaching from the west, results in a climate where extremes occur only when under the influence of unusually potent weather regimes. During the summer season, cold frontal passages are infrequent and, after modification, a change in air masses is difficult to ascertain. If a change is distinguishable, it is of short duration. The prevailing wind is from the west-southwest at 7 miles an hour. Rainfall is adequate, falling for the most part as a result of afternoon and evening thundershowers which occur on an average of 23 times during the summer.
Winters are cold even though the Canadian air masses are modified somewhat before reaching the area.
The wind flow is from the northwest at an average speed of 12 miles an hour. Located on the southern edge of the Appalachian mountains, Lebanon is situated between the persistent cloudiness of the mountainous section and the less cloudy areas to the shoutheast. The cloud cover is reduced since much of the moisture contained in the southeastward moving air is lost due to orographic uplift over the mountains. Daytime highs average in the upper 30's, and nighttime lowes generally drop into the lower 20's. Seventy-degree temperatures have been experienced during the winter season but are a rarity.