Weather Synopsis – June 24, 2024

James Murakami

Mon24th82/65Mostly sunny day with some mid/high clouds. Some mid/high clouds in the evening.
Tue25th80/63Mostly sunny day with variable mid/high clouds. Variable mid/high clouds in the evening.
Wed26th78/63Mostly sunny day except chance of early morning low clouds. Mostly clear evening.
Thu27th77/63Mostly sunny day except chance of early morning low clouds. Mostly clear evening.
Fri28th77/63Mostly sunny day except chance of early morning low clouds. Mostly clear evening.


In spite of stronger on-shore flow today (compared with the last couple of days), today was the warmest day of 2024 (to date) for some areas of the coastal plain. For the second consecutive day, UCLA reached at least 80 degrees (first 80 degree days of the year). Today was the warmest day on campus (83 degrees, assuming no late afternoon spike) since 12 November, 2023 (85 degrees that day). The Santa Monica pier managed to warm briefly to 74 degrees. The recent influx of “monsoon” moisture aloft (source partly from remains of once tropical storm Alberto) helped disrupt the local marine layer (area wide warm air from aloft mixed down into the low cloud field).

All the computer models continue to forecast similar strength, on-shore flow for the next couple of days. It may take a couple of days, but the low cloud field should “repair itself” by Wednesday (current “monsoon” air mass predicted to get shunted away by then). So, a better defined marine layer should bring noticeable cooling to the coast. The predicted shallowness of the marine layer, however, should limit the cooling trend as one travels farther inland. High pressure aloft, however, is forecast to get dislodged to the east later in the week. So, some modest cooling even farther inland should occur in the second half of the week. Still, with gradually warming waters (sea surface temperatures near 70 degrees off of southern Orange/northern San Diego Counties), the coolness of the early half of June shouldn’t repeat itself till autumn (“warm” marine layer till then).

The predicted cooling late in the week (back to seasonable temperatures for much of the coastal plain) should be short-lived. High pressure aloft is forecast to rebound late in the weekend and persist leading up to the 4th of July. At this point, the model consensus doesn’t show the warming getting any higher than it’s gotten in recent days. Most of the model solutions also don’t show any relevant, new “monsoon” moisture incursion next week. However, a slight error in predicted winds could easily change that outlook. With respect to temperatures near the coast (campus included), the weather wild card will be the integrity of any marine layer (even a shallow one). A well defined marine layer could keep any warming trend to a minimum. Otherwise, it looks like the extended, 4th of July weekend will be warmer than normal.

Next issued forecast/synopsis should be on Monday, 1 July.