I have been collecting weather data for Fallbrook since 25 September 1994, so I don't have a lot of data for Fallbrook and thus cannot report on events that happen only once per 10 years or longer. Nonetheless, the data that I have already collected give a pretty accurate picture of the mean temperature and sunshine percentage variation with the day of the year. The data also give some indication of the "normal" type of variability that happens within each year. The data were collected at my house in the Winterwarm area of Fallbrook at 690' elevation at 33° 20.33' latitude, 117° 13.24 West longitude.
I use two Taylor max-min thermometers, and manually read the recorded max and min temperatures once a day near sunset when I am home. If I am away, I record the max and min temperatures when I get back, and use the official Fallbrook temperatures to assign those measurements to the appropriate day.
I also record my estimate of the percentage of possible sunshine each day that I am in Fallbrook all day. I define the percentage of possible sunshine as the total number of hours of actual sunshine divided by the number of daylight hours.
My high temperature comes from my thermometer under my porte-cochere, mounted on the north side of a supporting post, separated from the wall by half-inch blocks of wood at the mounting screws. My low temperature comes from my thermometer mounted on a wood post in the ground several feet away from the west wall of my house. The thermometer is again mounted a half-inch from the post with wooden blocks. In addition to being fairly close to the house, two large trees block the view of most of the sky from that thermometer, which probably prevents recording temperatures as low as might be experienced in the middle of an open field.
For rainfall, I use a standard cheap plastic rain gauge available at hardware stores, placed in an open area in my yard. I read the gauge near sunset.
I have over a decade of weather for Altadena, Ca that I'll put on the web when I have time that will be useful for extending the rainfall comparison between years, and for determining events that happen only once per 10 years or so.
There are several caveats to be noted about the data, which are explored further in Analysis of Biases in Fallbrook Temperatures:
Copyright © 1997, 1998 by Tom Chester.
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
Comments and feedback: Tom Chester
Last update: 1 January 1998.
The plots may have been updated later - see the date at the top of each plot.