SLO County weather forecast for the week of April 18: Warm weather and clear skies

Last week, a trough of low pressure developed along the California coastline and allowed the marine layer to deepen, producing areas of night and morning fog and mist and below seasonal temperatures. The early part of this week will see a ridge of high pressure producing strong to gale-force (25 to 38 mph) northwesterly winds along the coastline, mostly clear skies, and warmer temperatures throughout the Central Coast.

A high-pressure ridge will build over the Central Coast on Sunday into Monday for warmer weather including near the coast, where overnight low-level marine cloudiness will decrease. The inland valleys (Paso Robles) will warm into the mid-80s and the coastal valleys (San Luis Obispo) in the mid-70s. The beaches will reach the 60s.

High pressure is expected to weaken on Tuesday into Wednesday in response to a low-pressure system passing to the north of Central Coast which will produce increasing overnight marine clouds, and cooler temperatures; however, strong to gale-force northwesterly winds continue along the coastline. The northwesterly winds will decrease on Thursday through Friday and the marine layer will deepen and spread farther inland. Many of the beaches will remain overcast throughout the day over this period.

Warmer weather is forecast next weekend as high pressure builds in behind the departing low-pressure system. The long-range models indicate dry weather will continue through the end of April. Unlike the rain records at Cal Poly, which reported entirely dry Aprils during the 2003 and 2012 rain seasons, the Diablo Canyon rain gauge has never seen a total lack of rain in April since records were started in 1976. This April could be the first one without any measurable precipitation at Diablo Canyon.

Surf report

Increasing northwesterly winds along the California coastline will generate a 4- to 6-foot northwesterly (310-degree, deep-water) sea and swell (with a 5- to 14-second period) along our coastline through Monday, increasing to 6 to 8 feet (with a 5- to 11-second period) on Tuesday through Wednesday.

A 4- to 6-foot northwesterly (290-degree, deep-water) swell (with an 8- to 11-second period) is forecast along our coastline on Thursday, decreasing to 3 to 5 feet by Friday.

Seawater temperatures will range between 49- and 52-degrees through Saturday.

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

PG&E safety tip

With the warm temperatures on Sunday and Monday,please remember to stay hydrated: Keep drinking plenty of water, even if you’re not thirsty. Avoid drinks with caffeine or alcohol. For more heat safety tips, please visit www.pge.com.

John Lindsey’s is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter @PGE_John.