The Greater San Francisco Bay Climate

    Spring   Birds migrating from more southerly latitudes begin
    showing up as early as mid January and extend through June.
    During this period  shorebirds, now in bright breeding plumages,
    fatten up in preparation for the long flight to their northern breeding
    grounds..Many of them remain in California through March or April
    before heading out. The forests reach the peak of activity in May
    and June with breeding displays and nest building activities of
    songbirds. Wildflower blooms peak in the valleys, coast side and
    desert about March/April, on into May and June in the foothills and
    higher elevations. In the coastal mountains black bears begin
    stirring out of their long winter nap around February/March hungry
    and foraging for food. Northbound California Gray Whales can
    occasionally be seen making their way back to the Bering Sea and
    Gulf of Alaska from Baja but are typically a little further off shore on
    this leg of their migration. Marine mammal colonies are still very
    active with the adults in the early stages of parenthood at this time.

    Summer    Hyperactive Hummingbirds zip and dazzling
    butterflies flutter from bloom to bloom in search of nectar while
    Ospreys make spectacular dives for unsuspecting fish.  
    Swallows amass by the hundreds and sometimes thousands
    scooping up flying insects on and above lakes, ponds and
    meadows. Residents bird such as the Wrentit, Towhees,
    Vireos and Brown Creepers, along with a large variety of
    Woodpeckers are busy raising their fledglings in the coniferous
    and broad leaf forests. Southern seabirds such as Brown and
    American White Pelicans fly up from the south perhaps to enjoy
    the cooler weather or better fishing and mingle with gulls,
    Cormorants, Avocets, Stilts & Herons. The coastal areas
    cooled by marine influence provide a respite from the summer
    heat while the Sierra and Coastal mountain ranges offer spring
    like conditions in the higher altitudes.

    Fall  The first signals of the fall migration actually happen in late summer
    as shorebirds begin trickling in to the coastline and estuaries in late July.
    This is the most exciting time of year for us as nearly 20 species of
    migrating raptors are funneled along the coast through the Marin
    Headlands using the thermals to gain elevation before crossing the open
    waters of the Golden Gate. During the peak of the hawk migration in late
    September sometimes hundreds of raptors can be witnessed in a single
    outing. At this same time of year the shrubs and trees become alive with
    migrant songbirds either in route to more southerly latitudes or setting up
    shop for the winter. Early fall rains can bring many unusual birds that will
    take shelter in woodland areas along the coasts and bays. This is also
    the best time of year for observing the rutting behavior of deer and elk.
    The California Gray Whales can be seen on their southbound migration
    starting in November while the Monarch Butterflies start showing up on
    land. Fall colors begin in September, peak in early October in the
    mountain areas, late October to early November at lower elevations.

    Winter  Habitat and seasonality bring constant change to the
    diversity and abundance of species in the area. Winter has the
    greatest variety of birds as many fall migrants stay on to enjoy
    the moist, relatively warm winter and join the resident birds like
    the California Quail. Millions of ducks, geese and grebes
    descend from the north through the Pacific Flyway to over-
    winter in the Klamath and Mono Basins, Central Valley and San
    Francisco Bay estuaries. This is also the peak time to observe
    marine mammals as they re-establish historic rookeries along
    the Pacific coast. Depending on when the first heavy rains
    begin, Steelhead Trout, Chinook and Coho Salmon begin their
    epic trip to spawning grounds.   These fish can occasionally be
    seen in the coastal streams and rivers throughout Northern and
    Central California during this time of year.
San Francisco based Nature Trip -  415-355-0450
Our home base in the San Francisco Bay Area enjoys a
temperate, marine climate with relatively mild weather all year.
The average temperature is 57°F.  Temperatures above 80°F
(27°C) or below 40°F (5°C) are infrequent. In the summer, fog
rolls in during late afternoon and tends to burn off mid-morning.
The warmest months are typically in the late summer or early fall.
Rain falls primarily November through April with average
precipitation, varying greatly by location, between 15 and 32

In the Bay Area alone, there are literally hundreds of
micro-climates within a vast variety of habitats including coastal
scrub and chaparral, foothill oak woodlands, coastal dunes,
moist, fog dependant redwood and coniferous forest.

Current  San Francisco Gate Weather
Nature's Calendar - California