The rain’s not over yet. See what’s ahead in SLO County’s weather forecast

This April turned out to be a pleasant surprise, with above-average rainfall recorded across the Central Coast.

These spring showers were especially welcome following the record warmth and dry conditions of March, and they pushed up rainfall totals for the current rain season, which lasts from July 1 to June 30

As of May 1, the San Luis Obispo County Regional Airport had measured 16.53 inches of rain, which is 95% of normal, up from 91% at the end of last month.

Paso Robles recorded 13.54 inches, reaching 116% of normal. Rocky Butte, typically the wettest location along the Central Coast, had received 38.22 inches, or 96% of normal, through the end of April. The Santa Maria Airport recorded 15.1 inches of rain, or 117% of normal.

Because historical rainfall totals drop off sharply in May, these percentages are not expected to change significantly through the end of the rain season.

However, storms can intensify quickly this time of year due to longer days and increased surface heating, which can create atmospheric instability.

For example, on May 5, 1998, a storm moved through the Central Coast producing thunderstorms with heavy rain, lightning and hail, along with a rare tornado that touched down early that morning near Cal Poly San Luis Obispo.

An upper-level, low-pressure system will drift southward along the California coast this weekend through Monday, bringing gentle onshore winds, cloudy skies, cooler temperatures and a chance of drizzle or light rain from Sunday night into Tuesday morning. Conditions will then shift to increasing northwesterly winds, clearing skies and a warming trend from Tuesday afternoon into next weekend.

A weak 557 decametre, upper-level, low-pressure system, centered about 100 miles west of the Central Coast, will drift southeastward, bringing moderate to fresh (13 to 24 mph) westerly winds and increasing clouds. Areas of drizzle or light rain will develop across San Luis Obispo and Santa Barbara counties from Sunday night through Tuesday morning, with the greatest chance of rain occurring on Monday as this system moves overhead.

This storm is expected to produce less than a tenth of an inch of rainfall, if your location is fortunate enough to receive measurable precipitation.

During this period, daytime highs will top out in the mid-60s across the inland valleys, including Paso Robles, and in the low-to-mid 60s for coastal valleys such as San Luis Obispo. Along the beaches, temperatures will generally range from the upper 50s to the lower 60s.

Fresh to strong (19 to 31 mph, with gusts up to 35 mph) northwesterly winds will develop Tuesday afternoon through Wednesday.

A 1,030 millibar Eastern Pacific high-pressure system will strengthen about 700 miles west of Cape Mendocino by Thursday, creating a steep pressure gradient along the California coastline.

This pattern will generate strong to gale-force (25 to 31 mph, with gusts up to 45 mph) northwesterly winds in the coastal regions during the afternoon and evening. These winds will ease overnight and during the morning hours, allowing areas of low marine clouds to redevelop along the coast.

These northwesterly winds could build to moderate gale-force to fresh gale-force (32 to 46 mph with gusts to 50 mph) on Friday and Saturday.

Temperatures will warm to the mid-80s in the inland valleys and mid-70s in the coastal valleys. The beaches will range between the high 50s and low 60s, except for the southerly facing beaches of Cayucos, Avila Beach and Shell Beach, which will reach the low 70s on Wednesday through Saturday.

Surf report

A 4- to 6-foot northwesterly (290-degree, deep water) swell (with an 8- to 18-second period) is expected this Saturday through Tuesday morning.

Increasing northwesterly winds along the California coastline will generate 4- to 6-foot northwesterly (300-degree, deep water) sea and swell (with a 5- to 14-second period) on Tuesday afternoon through Friday morning, increasing to 7- to 9-feet (with a 7- to 15-second period) on Friday afternoon through Saturday.

A series of Southern Hemisphere swell trains are expected to arrive along our coastline the following week.

Seawater temperatures are expected to range from 53 to 55 degrees through Tuesday, cooling to 50 to 52 degrees from Wednesday into Thursday. By Friday through Saturday, temperatures will drop further to between 49 and 51 degrees.

On this date in weather history (May 3)

1935: Snow, ice and sleet brought winter back to parts of southeast Minnesota. Minneapolis received 3 inches of snow to tie their May record, which was established in 1892. (1st-2nd) (The Weather Channel)

1954: The temperature at Polebridge, Montana, dipped to 5 degrees below zero to establish a state record for the month of May. (The Weather Channel)

1987: Thunderstorms produced large hail and heavy rain in Texas. Baseball size hail pounded Dublin, and 3.75 inches of rain soaked Brady. (Storm Data)

This week’s temperatures

LOWS AND HIGHS, PASO ROBLES

SUNDAY: 47, 68

MONDAY: 43, 67

TUESDAY: 43, 71

WEDNESDAY: 45, 80

THURSDAY: 50, 85

FRIDAY: 51, 83

SATURDAY: 52, 84

SUNDAY: 51, 84

LOWS AND HIGHS, SAN LUIS OBISPO AND COASTAL VALLEYS

SUNDAY: 52, 64

MONDAY: 50, 62

TUESDAY: 49, 68

WEDNESDAY: 50, 74

THURSDAY: 53, 77

FRIDAY: 52, 74

SATURDAY: 52, 73

SUNDAY: 53, 73

John Lindsey is a retired PG&E marine meteorologist. Email him at JohnLindseyLosOsos@gmail.com or follow him on X @PGE_John.