Weather Synopsis – July 1, 2024

James Murakami

Mon1st76/61Sunny remainder of day. Chance of late evening low clouds.
Tue2nd77/63Good chance of early morning low clouds; Otherwise, mostly sunny day. Mostly clear evening.
Wed3rd78/64Chance of some early morning low clouds; Otherwise, mostly sunny day. Clear evening.
Thu4th79/66Sunny day. Clear evening.
Fri5th81/68Sunny day. Clear evening.


Though things started warming up (in general) during the final ten days of June, the average temperature at UCLA wound up a tad lower than normal (for June as a whole). If longer range model forecasts hold up, this month (possibly through most of the summer) may be warmer than normal. How warm it gets, of course, remains to be seen.

In recent days, the low cloud field off of southern California made a comeback. The displacement to the east of upper level high pressure helped with a minor cooling trend during the period. After a weak, upper level trough passes through the state today, high pressure is forecast to rebuild into the state. This time, however, it should strengthen into the Southwest from the Pacific (instead of from the east, which is more common in summer). By the 4th of July holiday period (includes the weekend), a strong high pressure is forecast to bring very hot weather to most of the state (the Southwest in general). Even mountain resorts in the state (Sierras included) should experience several days of 90 degree weather. Any relevant cooling trend for most in the state isn’t likely to start before early next week. It may take till the end of next week for the interior sections (based on today’s model consensus).

The one uncertainty (for me) is how the marine layer will fare as high pressure takes over the region. No full fledged, off-shore flow is expected in southern California (at most, some periods of marginal, northerly flow). The high pressure will definitely make the current marine layer quite shallow. After tomorrow, marine layer clouds/fog may be restricted to the beaches. An intermittent, coastal eddy, however, may provide support for more low clouds than what is typical with strong high pressure aloft. On the other hand, sufficient mixing of dry, warm air from aloft into the marine layer would disrupt the low cloud field (possibly diluted to the point of no clouds over the coastal waters).

It is almost a guarantee that much hotter than normal weather will prevail by midweek for well inland locales (widespread triple digit weather in the valleys lasting through at least early next week). At some point, the inland coastal plain should warm into the 90s. Nearer the coast, it will depend on what marine layer remains (even a diluted one). For this forecast, I show the campus warming ever slowly through the week. However, it’s quite possible that a more significant jump will take place by Thursday (mid/upper 80s for a few days). I do not, however, believe the campus area will reach the 90 degree mark (not unless a full fledged, off-shore flow develops).

All through the up coming period, no “monsoon” moisture incursion is expected in the state (not common with high pressure that build from the west). At some point, as the high pressure center migrates east of the state (later next week), there will be some chance of wind flow that imports “monsoon” moisture into the Southland (with regard to chances for mountain/desert showers and thunderstorms). At this point, I don’t see a relevant chance of that happening before the subsequent weekend. There is a chance that the coastal plain will be a little humid at times, but that source will come from any weak, on-shore flow (local ocean slightly warmer than normal).

Next issued forecast/synopsis should be on Monday, 8 July.