I would classify Loomis as an "Intermediate Mediterranean / Semi-mediterranean" climate. It is Mediterranean in the sense that there is a dry season and a wet season. The dry season usually lasts five months and the wet season lasts seven months. Rainfall during the late spring, summer and fall, dry season, averages 8.71 inches, while the winter and spring, wet season, averages 34.24 inches. The usage of describing the climate as intermediate / semi-mediterranean results from the Loomis Basin being located between two climate zones. Loomis borders the climates of Southern California / Central California and the Northwest (Oregon-Washington). In addition, Loomis has the distinction of a first tier interior climate with overriding marine influences. In other words, it is still situated within the western, moist side of the Sierra-Nevada mountains, but with more interior characteristics. These geographic factors create a more distinct "four season" temperature difference.
As the years of my keeping weather records have passed by and the statistical data has accumulated, it could be argued that the climate of Loomis holds unique micro climate characteristic (Also see Loomis, CA Weather / Climate History). These are differences even unto the climates of Loomis's closest neighbors of Rocklin-Roseville and Auburn, California. Regionally this is not unusual in this part of California due to the topography. Because the Loomis Basin sets at the base of the Sierra-Nevada mountain range, elevations increase rapidly to the east in hundreds of feet per mile. While this change in elevation is more gradual to the west, it is somewhat significant as it relates to climactic differences.
Of note, and not too well known outside this area, spring can bring small tornadoes to the Valley. This usually occurs in March and April and they are certainly not the size of those in the Midwest, Oklahoma or Texas. Hurricanes never occur, due to cold water temperatures offshore Northern California in the Pacific Ocean.
The annual rainfall in Loomis, at the time this article was written, with at least 10 year plus period of records, was 42.95 inches. However, it should be noted that these years were wetter than previous years, based on regional 100 year records. Additional records should be kept in order to determine more precise averages. It is more likely the actual average is around 37 to 39 inches. As mentioned previously, most of the precipitation in Loomis falls during the months of November, December, January, February and March.
In conclusion, one could say that the climate in Loomis is very pleasant and healthy. This is a climate which is probably one of the best and most desirable in the world.
*(Month to month statistics on Loomis, CA with an annual focus:)
(Written by Jeff Parks)