SLO County weather forecast for the week of Dec. 21

Here is this week’s weather forecast by PG&E meteorologist John Lindsey.

The sun will reach its southernmost point of the year Monday evening and usher in winter at 8:48 p.m. As if on cue, a weak cold front will gradually move southward and produce mostly cloudy skies and scattered rain showers Monday afternoon into Tuesday morning throughout the Central Coast. Snow levels with the mild system will remain above 6,000 feet Monday before rising to around 7,000 feet Tuesday. A few residual rain showers may continue into Tuesday afternoon. Overall, total rainfall amounts are expected to range between a quarter and three-quarters of an inch.

Strong to gale-force (25 to 32 mph) northwesterly winds will develop along the coastline Tuesday afternoon through Wednesday. This condition will produce mild temperatures, partly cloudy skies and areas of night and morning marine low clouds in the coastal regions.

A stronger cold front will move through San Luis Obispo and Santa Barbara counties on Thursday morning with increasing southerly winds and rain. This cold front will be followed by moderate gale-force to fresh gale-force (32 to 46 mph) northwesterly winds, a few rain showers and cooler temperatures on Christmas Eve into Christmas Day. Snow levels could drop to around 3,500 feet Thursday and down to 3,000 feet early Christmas Day with low snow possibly hampering holiday travel.

Increasing Santa Lucia (northeasterly) winds will produce dry and mostly clear and cold conditions except for areas of dense morning ground fog in the inland valleys Saturday. Another cold front is expected to produce increasing clouds Sunday and rain next Monday.

Monday’s surf report

Today’s 6- to 8-foot northwesterly (300-degree, deep-water) swell (with an eight- to 15-second period) will become an 8- to 10-foot northwesterly (310-degree, deep-water) sea and swell (with a seven- to 17-second period) Tuesday morning.

Strong to gale-force (25 to 38 mph) northwesterly winds along the Northern and Central California coastline will generate a 10- to 12-foot (310-degree, deep-water) sea and swell (with a four- to 15-second period) Tuesday into Wednesday, decreasing to 7 to 9 feet by Thursday morning.

Moderate gale-force to fresh gale-force (32 to 46 mph) northwesterly winds along the Northern and Central California coastline will generate an 11- to 13-foot northwesterly (310-degree, deep-water) sea and swell (with a five- to 14-second period) Thursday afternoon into Friday, decreasing 6 to 8 feet (with an eight- to 13-second period) Saturday. This northwesterly swell will further lower to 4 to 6 feet (with an eight- to 11-second period) Sunday. A potentially higher-energy swell could develop along our coastline Dec. 28 and 29.

Seawater temperatures

Seawater temperatures will range between 57 and 59 degrees through Thursday, decreasing Friday into Saturday.

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At PG&E, your safety is our first concern. This winter is likely to have a very strong El Niño effect that may bring more than normal amounts of rain across California. Please visit www.pge.com for preparedness tips.

This story was originally published December 20, 2015 at 8:26 PM with the headline "SLO County weather forecast for the week of Dec. 21."