Hi Ian
The countryside is beautiful in your region. It appears that there are many deciduous trees at the lower elevations and conifers at the higher elevations. Are the coniferous trees native? Native trees but planted as a tree farm for timber harvest? There is so much I do not know about your part of the world.
Frosty nights are frequent at the higher elevations of the Sierra Nevada Mountains. The first significant snow fell in the Sierras a few days ago. This is a bit early. Now the weather is warm again and the snow will be gone by today or tomorrow. Traditionally, the first frost at our El Dorado County farm is 31 October. Now, with climate change, it is generally much later. The weather change has brought the White-crowned Sparrows and other birds down from the Sierra Nevada. The seasons are changing.