A Break

In Jamul (south-central San Diego County) we have had weeks of absolutely unrelenting sunshine, dry air, and heat — in the high 90s or low 100s (°F) every afternoon. Today it looks like we're going to get a break. The upper chart (at right) shows the temperature (red line, left scale) and humidity (green line, right scale) for the past week. Note that these are 60 minute running averages, so some of the peaks and valleys are smoothed out. You can see that our temperatures have been following a pretty stable pattern, with a slight dip yesterday — but today, a major drop. Debi and I took a nice walk up the hill next to our property, and it was a crisp 49 °F and misty as we trekked — very pleasant walking weather. The dogs loved it, too (especially when we spooked a barn owl out of an oak, and it swooped down within a few feet of us on its way out).

The lower image at right shows solar radiation (basically, how bright the sun was) for the past week. It's been day after day of absolutely perfect, cloudless days. Hot. Dry. Bright. Hot. But this morning (the rightmost little piece of that line) it was different — instead of zooming nearly straight up (indicating very bright sunlight as soon as the sun pops up over the horizon), it's kind of drifting upwards. This is because (as I look out the window) we have a fairly thick layer of mist shielding us from our local star. This probably won't last more than an hour or two, but it means that the total energy deposited on us today by the sun will be considerably reduced — and unless a hot wind blows in from the desert, that means that our peak temperature will also be reduced, perhaps in the 80s (°F).

As usual, click on the images for a bigger view. These came from the web page for my weather station.