Portola Valley Weather Trend Charts

This past weather information is provided AS IS and strictly for recreational, educational, and informational purposes only; we disclaim liability of any kind whatsoever, including, without limitation, liability for quality, performance, merchantability and fitness for a particular purpose arising out of the use, or inability to use the data. The information may be inaccurate or incomplete based on how well the corresponding weather station successfully or unsuccessfully reported or recorded it with the instruments which measured the weather at the time; including gaps between hours or even days. Specifically, LocalConditions.com and this data, as presented, may not and should not be used as a reference for any reason relating to legal proceedings, insurance claims, recovery, loss prevention, making predictions, or critical decisions. Lastly, the weather station may be miles away from the actual area of interest. This data may not be leeched or republished.

The "Approx. Precipitation / Rain Total" is calculated in whole based on the last measurement from each hour reported - which is accumulative and reset at the beginning of each hour - ideally. However, some stations reset at the wrong time, such as a few minutes after the hour. We have tried to account for this issue. Most gauges report multiple times per hour. For example, a measurement of precipitation at 8:15am could be 0.04 in. of water - then when a measurement is taken at 8:30am might be 0.06 in. - and at 8:56am might be 0.08 in. So, the accumulative total for that hour would be 0.08 in. - not calculated together to equal 0.18 in. of precipitation. Finally, each hourly total for the day is summed to provide the "Approx. Precipitation / Rain Total" figure.

One other note: if the total is 0, but there was obviously rain - then the instrument is not properly distributing its data from the station. The issue could be temporary or permanent.