A potent storm system is set to bring rain and possible thunderstorms to Pasadena on Sunday, with a 100 percent chance of precipitation, before a dramatic warm-up sends temperatures soaring into the low 80s by next weekend, according to forecasters with the National Weather Service in Oxnard.
Rain and Thunder Arrive Sunday
Pasadena residents waking up Sunday morning will find cloudy skies and rain already underway. Overnight conditions brought a 60 percent chance of showers under cloudy skies, with temperatures settling near 50 degrees and light south-southwest winds around 5 mph.
Sunday marks the main event. Rain and possibly a thunderstorm are expected before 2 p.m., with steady rain likely through the rest of the day. The high will reach only about 61 degrees — well below seasonal norms — as southwest winds blow at 5 to 10 mph with gusts up to 15 mph. Rainfall totals between a quarter and a half inch are anticipated, with lighter amounts possible overnight Saturday into Sunday morning.
Residents should plan accordingly: keep an umbrella handy, expect slick roads during the morning commute window, and be mindful of brief but potentially heavy downpours, especially in foothill areas where localized runoff is possible near the Angeles National Forest.
Storm Exits Sunday Night
Relief arrives by Sunday evening. The chance of rain drops to 40 percent before 11 p.m., and skies will turn partly cloudy as the system pushes east. Temperatures will fall to around 46 degrees overnight, with west-southwest winds at 5 to 10 mph tapering off to light and variable conditions. Gusts may still reach 15 mph early in the evening.
By Monday morning, the storm will be in the rearview mirror. Mostly sunny skies return with a high near 61 degrees. Afternoon winds will pick up from the west-southwest at 10 to 15 mph, gusting to 20 mph — the strongest winds in the forecast period. Monday night will be mostly clear and cool, with lows near 47 degrees.
A Striking Warm-Up Ahead
The real headline of the week may be what follows the rain. After holding steady near 61 degrees on both Sunday and Monday, temperatures will begin a steady climb that doesn’t let up.
Tuesday jumps to a sunny 70 degrees. Wednesday pushes further to 74. By Thursday, expect highs around 73 under mostly sunny skies, and Friday climbs to 76. The week culminates next Saturday with a high near 81 degrees — a swing of 20 degrees from Sunday’s storm-cooled high. Overnight lows will gradually warm as well, rising from the mid-40s early in the week to the low 50s by Friday and Saturday night.
Precipitation Details
All meaningful rainfall in this forecast window is concentrated in a roughly 24-hour period from Saturday night through Sunday evening. The heaviest rain, accompanied by the thunderstorm threat, falls before 2 p.m. Sunday. NWS forecasters estimate a quarter to half an inch of new rainfall during the day, with lighter amounts of less than a tenth of an inch possible both overnight Saturday and during Sunday evening’s lingering showers.
No additional precipitation is expected after Sunday night. The remainder of the week looks thoroughly dry.
Wind Outlook
Winds remain relatively tame throughout the forecast period. Sunday’s southwest winds at 5 to 10 mph with 15 mph gusts will be the steadiest, coinciding with the storm. Monday afternoon brings the strongest gusts of the week at 20 mph out of the west-southwest. After that, winds diminish and are not a significant factor for the remainder of the week.
Pasadena’s typical afternoon canyon breezes should resume by midweek as high pressure builds over the region.
Weekend Outlook
Next weekend is shaping up to be outstanding. Friday will be sunny with a high near 76 degrees, and Saturday promises to be the warmest day in the extended forecast at 81 degrees under sunny skies. Overnight lows in the low 50s will make for comfortable evenings. It will be ideal weather for visiting the Huntington Gardens, exploring Old Town, or catching up on outdoor errands after this week’s wet start.
Advisories and Recommendations
No formal watches or warnings are currently in effect for the Pasadena area, but the NWS thunderstorm forecast for Sunday morning warrants caution. Residents in hillside and foothill neighborhoods should watch for localized debris flows, particularly in areas affected by recent brush clearing. Drivers should allow extra travel time Sunday morning and keep headlights on.
With the warm-up later in the week, allergy sufferers may want to take note — the combination of rain followed by several days of sunshine and rising temperatures often triggers a surge in pollen counts across the San Gabriel Valley.
Looking Ahead
The extended outlook through next Saturday shows a solidly dry and progressively warmer pattern. High pressure is expected to dominate the region, bringing abundant sunshine and temperatures that climb steadily from the upper 60s into the low 80s. No additional rain chances appear on the horizon.
The Bottom Line
Pasadena faces one more round of wet weather Sunday — bring the rain gear and drive carefully — before the skies clear and a sustained warm-up takes hold. By midweek, the storm will feel like a distant memory as temperatures surge toward 70 and beyond. Next weekend’s forecast of sunny skies and highs near 81 degrees offers a preview of the warmer months ahead. Enjoy the rain while it lasts; dry days are on the way.
Here is the latest National Weather Service forecast for Pasadena as of Sunday, April 12 at 12:52 A.M.
Overnight: Rain likely. Cloudy, with a low around 50. South southwest wind around 5 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Sunday: Rain and possibly a thunderstorm before 2pm, then rain likely. High near 61. Southwest wind 5 to 10 mph, with gusts as high as 15 mph. Chance of precipitation is 100%. New rainfall amounts between a quarter and half of an inch possible.
Sunday Night: A 40 percent chance of rain before 11pm. Partly cloudy, with a low around 46. West southwest wind 5 to 10 mph becoming light and variable in the evening. Winds could gust as high as 15 mph. New precipitation amounts of less than a tenth of an inch possible.
Monday: Mostly sunny, with a high near 61. Light and variable wind becoming west southwest 10 to 15 mph in the afternoon. Winds could gust as high as 20 mph.
Monday Night: Mostly clear, with a low around 47. West southwest wind 5 to 10 mph becoming light and variable in the evening. Winds could gust as high as 15 mph.
Tuesday: Sunny, with a high near 70.
Tuesday Night: Clear, with a low around 49.
Wednesday: Sunny, with a high near 74.
Wednesday Night: Partly cloudy, with a low around 52.
Thursday: Mostly sunny, with a high near 73.
Thursday Night: Mostly clear, with a low around 50.
Friday: Sunny, with a high near 76.
Friday Night: Mostly clear, with a low around 52.
Saturday: Sunny, with a high near 81.
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