Here in our part of Northern California, climatic change is having a significant impact on both managed and unmanaged ecosystems. Many of the climatic changes taking place have been progressing for years. We are now seeing weather events that were unheard of 30 years ago. Many ornamental plants species that once thrived in our garden are now ineffective, either performing poorly or have died. Not only do we need to reassess our plant choices for our garden, but we also have to reevaluate the methods we use to cultivate our plants. We firmly believe that a satisfying and stable garden ecosystem can be created that is resilient to rapidly changing and highly variable climatic conditions now taking place. These changes may not be easy to accept or implement, but gardening can continue to be a rewarding and pleasurable activity into the future.
Below are a few charts where we have quantified some of the high temperature extremes we have been experiencing, both past and present. Many other impactful climatic changes have been taking place, however these are some of the most noteworthy to report at this time.
The recent record breaking October 2024 heat wave ended on 8 October. Below is a chart plotting the high temperatures for this event. Daily high temperatures for the record-breaking heat wave of 28 September to 8 October 1987, and the 30-year average high temperatures for this time period are also included. Temperatures are in degrees Fahrenheit.
The recent October heat wave is of a similar magnitude and duration as the October 1987 heat wave. This year, a number of daily high temperature records were broken and the record high temperature for the month of October was tied. This heat wave was preceded by the warmest June through September time period on record. Many record breaking high temperatures were broken during this time period. Below is a chart recording the number of ≥ 90 F (32.2 C) high temperatures from 1988 to 2024. There have been 103 days with ≥ 90 F (32.2 C) high temperatures so far this year. This ties the record set in 2008. Hopefully we are finished with these high temperatures for the year, however the weather has been very difficult to forecast in this regard.
This year we set a new record for the number of days with high temperatures ≥ 100 F (37.78 C), at 50 days. This exceeds the old record of 37 days set in 2022. This new record exceeds the old record by 13 days. This is an extraordinary new record that is of great concern.
When analyzing this record with the data recorded on the histogram pictured above, the changes taking place become more alarming. Prior to 2008 we never recorded a high temperature above 110 F (43.3 C) in the 40 plus years we have been recording weather and climate related data at our Placerville farm. Now these high temperature extremes are occurring on a near yearly basis and we are now experiencing these temperatures for more than one day most seasons.
The weather and climate are in a constant state of flux, however the trends show no sign of stabilizing or declining. Currently our data and data from around the world suggest that these trends are accelerating. To successfully garden we are hoping to stay ahead of these trends and create a satisfying garden into the future.
[Jasmin]: If you think these temperatures are something, let me tell you about the lows! For months, the average low temperature has been around 14 C. During many of these heat waves, the temperature around midnight was frequently around 22 C. In the past, our area was always much cooler, influenced by the nearby river, and forest which has fallen to development. We would normally have a couple of hot days, and maybe a warm night that at most would be 12 to 14 C. This would quickly dissipate, blown away by the Delta breezes. These cool, ocean breezes would come through the gap in the coast range, following the river from the Bay Area and Delta up the Sacramento Valley. When the winds were strong enough, they would cool not only our immediate vicinity, but the entire valley and reach the foothills. This year, there were no cooling Deltas. The air was incredibly still. As for the foothills, in the past cool mountain air would sink during heat waves, so if cool air did not come from a strong Delta breeze, it would come from higher up the mountain. That mountain air always carried wonderful memories, the scents of childhood camping. Since the Caldor Fire, there is nothing, and there was absolutely no cooling.
After such a dismal survey, we must choose our bright spots to nurture hope. I have managed now and then to capture some of the more miraculous survivors during this long season of upheaval:
We begin with Aristolochia californica, which had a very long bloom period this year.
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