Livermore Weather

September is Livermore's best month, at least by the numbers. September 2025 recorded the highest comfort score in the 18-month dataset at 89 out of 100, with an average high of 72.1 degrees and a low of 53.5. That is almost ideal: warm enough to enjoy the outdoors but not the oppressive heat of a summer peak. March and April 2025 tied for second at 88 comfort, both with highs in the upper 60s to mid-70s, strong sunshine (11 to 12.9 hours per day), and almost no rain. May 2025 also hit 88 with 13.6 hours of daily sunshine and zero inches of precipitation, making it the sunniest month in the record. If you are visiting for the wine country experience, September gives you harvest season atmosphere with more forgiving temperatures than August. Spring visitors get long daylight hours and the Livermore Valley at its greenest before the summer heat sets in. Any of those four months will reward you with Livermore weather at its most comfortable.

Hot, by Bay Area standards. Livermore sits at the eastern end of the Tri-Valley, where the Coast Range no longer buffers inland heat, and summer highs regularly push into the mid-to-upper 80s. June 2024 averaged a high of 88.2 degrees, July 2024 hit 84.9, and August 2025 came in at 82.9. Heat waves can push temperatures well above 90. This is a consequence of geography: Livermore is one of the hottest cities in the Bay Area because it sits in a funnel where warm air from the Central Valley can push westward while cool marine air from the coast takes longer to arrive. The afternoon Delta breeze does eventually reach Livermore, which is why comfort scores stay above 83 even in the hottest months: the air moves. That said, triple-digit days are possible in June and July. For more context on why Livermore runs so much warmer than the coast, see why Livermore Valley is the hottest part of the Bay Area.

Significantly warmer. On a typical summer afternoon, Livermore can be 20 to 30 degrees hotter than San Francisco. When San Francisco is sitting at 62 degrees under fog, Livermore might be 88. The mechanism is simple: San Francisco is right on the ocean and gets the full force of the marine layer. Livermore is 40 miles east through a series of valleys, far enough inland that the fog rarely arrives with much intensity. This is the Bay Area microclimate effect at its most dramatic. The 18-month average high for Livermore is 71.7 degrees, which may not sound extreme, but it reflects a full year including cool winters. Summer averages consistently run 12 to 18 degrees above what you would find in San Francisco or Half Moon Bay. If you are escaping the summer fog that blankets the coast, Livermore is one of the most reliable places in the region to find actual warmth. The flip side: there is no ocean breeze to save you on truly hot days. See why the Bay Area has so many microclimates for a deeper explanation of the forces at work.

Late September through early October is the classic harvest window, and the weather usually cooperates. September 2025 had an average high of 72.1 degrees with a comfort score of 89, which is ideal for sitting outside at a tasting room. The vines are active, the valley smells like crushed grapes, and the heat has stepped back from the August peak. October is more variable: October 2025 brought 3.68 inches of rain and a comfort score of 78, while October 2024 was similarly wet. Early October is usually still dry; the rain tends to arrive in the second half of the month. Spring is an underrated time for outdoor tasting. April 2025 averaged 76.7 degrees high, almost no rain, and 12.9 hours of daily sunshine with a comfort score of 88. May is even sunnier, with 13.6 hours of sunshine and zero precipitation. The vines are leafing out, the crowds are smaller than summer, and the temperatures are genuinely pleasant. Avoid peak summer if heat bothers you: July and August highs in the mid-to-upper 80s make midday outdoor seating uncomfortable at many wineries.

Less than most of the Bay Area. Livermore averages 1.7 hours of morning fog per day across the 18-month record, which is one of the lower figures in the region. The marine layer that socks in San Francisco and the coast does push inland overnight, but it usually does not extend all the way to Livermore with much intensity. When fog does appear, it tends to be light and burns off quickly, often within the first hour of daylight. November 2025 was the foggiest period in the dataset at 3.7 hours per morning, coinciding with the onset of the rainy season and longer nights. Summer months average around 1.2 to 1.9 hours. The practical upside: if you are driving out to Livermore for a morning winery visit or a walk in the hills, you are less likely to deal with the thick marine layer that can hold on through noon in places like Half Moon Bay or Daly City. For an explanation of why the fog forms and why it diminishes heading east, see why morning fog forms in the Bay Area.

A lot. The 18-month dataset shows approximately 271 perfect days per year, and the sunshine numbers back that up. May 2025 topped the chart at 13.6 hours of sunshine per day with zero rain. April and June both averaged over 12.9 and 13.2 hours respectively. Even in winter, Livermore gets respectable sunshine: December 2024 averaged 8 hours per day, which is notably higher than the Bay Area coastal average for the same month. The annual average across the full dataset is 9.9 hours per day, which is strong for the region. Livermore benefits from being east of the marine layer influence. The fog that suppresses sunshine in San Francisco and along the coast reaches Livermore in diluted form, and the clear Central Valley air to the east has minimal cloud cover through spring and summer. The result is a sunshine budget that rivals much of Southern California from April through September. If sunshine is your primary criterion, Livermore is one of the most reliable places in the Bay Area to find it.

The answer depends heavily on the season. In summer, pack for heat: lightweight, breathable clothing, sunscreen, and a hat. The sun here is direct and temperatures by midday can be in the high 80s with limited shade at many outdoor venues. An extra layer is still worth having for the drive home in the evening when temperatures drop into the mid-to-upper 50s, but midday heat is the main event. In spring and fall, a light jacket for the morning is enough. April and October mornings can start in the upper 40s, so a layer you can remove by 10 a.m. is the right approach. In winter, dress for actual cold by Californian standards: November through January lows regularly drop into the low-to-mid 40s, and rain is common. A waterproof shell and comfortable layers will serve you better than a single heavy coat. Year-round, sunscreen is worth applying: at 489 feet of elevation with clear skies, UV exposure accumulates quickly, and Livermore's lack of coastal haze means the sun hits with more intensity than visitors from the city sometimes expect.

For most of the year, yes, and during summer it is often the preference. Livermore's outdoor dining scene is built around its climate: the warm, sunny afternoons that dominate April through October make patio dining genuinely comfortable. April 2025 averaged a high of 76.7 degrees, May hit 80.2, and June through August ranged from 80 to 88 degrees. At those temperatures, a shaded patio with a breeze is ideal. The afternoon Delta breeze that arrives around 2 to 4 p.m. in summer actually helps, cooling down what would otherwise be uncomfortable heat. Evening dining in summer is also pleasant, with temperatures dropping gradually through the 70s into the 60s after sunset. Winter outdoor dining is less appealing. December and January average highs are only in the mid-to-upper 50s, and both months carry real rain risk. Heated patios with overhead cover work in those months, but it is a different experience than a warm spring afternoon at a winery. Nearby Pleasanton has a similarly warm outdoor dining climate and is worth combining into a day trip.

This is a real phenomenon across much of the inland Bay Area, and Livermore shows it clearly. In the dataset, September 2024 averaged a high of 80.9 degrees with a comfort score of 86, very close to July 2024's 84.9 degrees. September 2025 had a comfort score of 89, actually higher than July 2025's 84. The explanation involves the seasonal weakening of the marine layer. In June and July, the temperature gradient between the cool Pacific and the hot Central Valley is at its strongest, which drives vigorous afternoon sea breezes inland. By late September, the ocean has warmed slightly and the Central Valley begins to cool, reducing the pressure gradient and slowing the afternoon onshore flow. With less marine influence, late September can produce warm, calm days that feel more comfortable than the hot-and-breezy peak of summer. For a detailed breakdown of this pattern across the region, see why September is sometimes hotter than July in the Bay Area.

The rainy season runs from November through March, with January as the historically wettest month. January 2025 recorded 4.14 inches of rain and a comfort score of 76. November 2025 was the wettest month in the dataset at 3.71 inches, and November 2024 brought 3.35 inches. October marks the transition: some years it stays dry through most of the month, others see early season storms arrive in the first week. The rain pattern here is classic Northern California: multi-day wet periods followed by clear stretches, rather than persistent drizzle. An atmospheric river can dump 2 to 3 inches in 48 hours, then the sky clears and you get a week of 60-degree sunny days. The dry season is genuinely dry: May 2025, June 2025, and June 2024 all recorded zero inches. July through August is essentially rain-free. With about 64 rainy days per year, Livermore is drier than most of the Bay Area hills and significantly drier than the Santa Cruz Mountains. For more on what drives these winter rain patterns, see the rainiest months in the Bay Area. Del Valle Regional Park nearby sees similar seasonal patterns and the reservoir reflects the full impact of the wet season.