Daily high temperature, low temperature, and precipitation from the TomKat weather station, along with the normal monthly range of temperatures observed since the weather station was established. Note: Gaps in weather data occurred when the weather station was being upgraded.
In 2020, TomKat experienced a new record high temperature of 97°F on September 06, 2020, beating the previous record of 96.2°F set just last year on September 25, 2019. High temperatures in 2020 also exceeded the normal range of high temperatures on several other dates in May, June, and August. The lowest temperature recorded in 2020 was 35.6°F on both February 03 and February 19, missing the record low of 31.1°F set on February 20, 2018. The single rainiest day in 2020 (through September 22) was 0.85 inches on January 16. The rainiest day ever recorded was December 11, 2014, with a total of 7.74 inches.
Click & drag the slider at the bottom to view different dates.TomKat’s high temperatures have been warmer than estimated historic averages in almost every month since November 2017, including during the growing season (March-June, shaded). Low temperatures were warmer than historic averages particularly during the extended drought.
Values greater than zero are above the estimated historic average (1980-2010)*, and values below zero are below average.
*Historic averages are estimated from comparing current TomKat and Half Moon Bay data, and applying corrections to historical averages from Half Moon Bay, 1981-2010.
We examined two drought indices from the National Centers for Environmental Information: the Palmer Drought Severity Index (PDSI) and the Palmer Z Index. The PDSI is an indicator of long-term drought that takes into account precipitation and temperature over several months, while the Z index measures short-term drought on a monthly scale, and can better reflect recent storms and soil moisture conditions.
The PDSI for Central Coastal California entered drought conditions early in 2013, which persisted nearly 4 years until October 2016, including over two years of extreme drought from June 2013 through November 2015. Conditions were largely normal through 2017, returned to moderate drought for much of 2018, and have stayed in the normal range since.
In the legend at top right, click on the lines for North Coast and South Coast to compare how these regions have fared over the same time period. During the extended drought, conditions in Northern Coastal California were never quite as dry, and Southern Coastal California generally fared worse. Northern and Southern Coastal California were also in the normal range throughout much of 2019, and in 2020 have switched places such that Northern Coastal California is currently the driest.
The PZI more readily shows the impact of big storms, such as the extremely moist conditions in February and May 2019, January 2017, October 2016, and December 2014. Central Coastal California has not yet had any moist short-term conditions in 2020.
In the legend at top right, click on the lines for North Coast and South Coast to compare how these regions have fared over the same time period.
This interactive web page was produced in R using rmarkdown and the plotly package. The code used to produce this web page is available on Github.
Please contact:
Chelsea Carey, PhD
Senior Soil Ecologist
Working Lands Group
Point Blue Conservation Science