Posted May 16, 2010, 10:46 AM.

May and especially June are notorious for coastal morning low clouds, that often spread inland. The western inland valleys in particular see marine layer more often than not, although they tend to burn off quickly, often by mid-morning.

Monday and Tuesday of this week are typical of what happens when low pressure systems arrive in the region this time of year.

The marine layer is expected to be very deep and skies will clear to partly cloudy in the afternoon.

In some cases, overcast skies can last the entire day.

This is also the time of year when temperatures in inland communities begin to diverge.

Fallbrook and De Luz, for example, where morning low clouds linger longer, stay mild. Temecula and Murrieta, which frequently get morning low clouds this time of year, are typically warm. And communities around the Elsinore convergence, such as Lake Elsinore, Wildomar, Menifee and Hemet, begin to heat up. In addition to fewer morning low clouds, those communities also get less vigorous onshore winds.

North of the Elsinore convergence, cities such as Riverside and Moreno Valley are warm but a few degrees cooler than Lake Elsinore. Morning low clouds are more frequent, especially in Riverside.

The next dose of heat currently looks to be on Thursday, which will take some communities into the 90's; the spread in temperatures should be apparent.