Have just returned after two and a half weeks in the US. We arrived in Los Angeles on Saturday October 6th to cloudy skies but warm conditions and the following day went down to Manhattan Beach and enjoyed fine and sunny weather with temperaures in the mid-70s.
After a couple of days, we travelled to Palm Springs where we spent six days. After a fine and hot day, the weather changed markedly on the Thursday. A LP system, initially weak and disorganised off the Califoirnia coast, developed and moved inland on a southerly track crossing southern California bringing rain and thunderstorms to LA and much of SoCal. In Palm Springs, I saw thunder clouds over the mountains and heard thunder but in the resort itself we had a couple of drops of rain on a "cool" day for the area (maximum around 80F). There was a gusty NW'ly wind to0 accentuate the chill.
For those who don't know, Palm Springs has had an incredibly hot year with more than 120 days with maximum values above 100F. The area around Thermal, just to the east, is often the warmest part of the continental US. Anyway, after that mixed 24 hours, the weather returned to "normal" with clear skies and hot sunshine though temperatures were a notch below average with values around 91F though it was warming as HP developed over central California.
From Palm Springs, we moved up for a week to Vegas and enjoyed glorious conditions. Unbroken sunshine, light winds and low humidity with daytime maxima in the low to mid-80s and night temperatures comfortable in the mid-60s. For the final weekend, we moved from the Strip to Lake Las Vegas and the weather began to change as the HP began to weaken and move east in the face of a buckling jet stream and a strong trough from an active LP off the north California coast which came inland and developed a secondary feature over Montana.
We endured increasingly strong and gusty SW'ly winds with falling humidities but still fine weather. Coming back to LA on Tuesday, the wind on I-15 was noticeable but was indicative of a building HP cell over the Great Basin and the onset of a Santa Ana wind promising much warmer values for Southern California (Palm Springs back into the 90s, LA in the 80s) but a big fire risk with humidities in single digits.