President Reagan Monday settled into his first full day of a California vacation, secluded at his mountaintop ranch and content to leave politics to the Democrats at their national convention in Atlanta.

The president, escaping the heat and humidity of the nation's capital, and first lady Nancy Reagan arrived Sunday and immediately slipped into the privacy of their 688-acre ranch in the often fog-shrouded hills about 20 miles from Santa Barbara.White House spokesman Marlin Fitzwater said Reagan had no real interest in watching the Democratic National Convention on television and might find it boring.

National security adviser Colin Powell and other aides will keep the president posted on various matters during his weeklong retreat, but Fitzwater said Reagan had no public activities planned this week.

But Reagan will not be dormant during the fall campaign.

Sometime after Vice President George Bush is nominated at the Republican National Convention in August, Reagan will be on the campaign circuit in an effort to elect the man who fought him for the Republican presidential nomination in 1980. No active political campaign role, however, is expected for Reagan until after the traditional Labor Day kickoff.

Bush was vacationing near an undisclosed fishing hole in northwestern Wyoming.