If you’re planning a move to the Peninsula or just visiting Stanford for a weekend, you’ve probably heard the hype about California’s "perfect" weather. People talk like it’s 72 degrees and sunny every single day of the year. Honestly? That is a total myth. While Palo Alto is gorgeous, the reality of Palo Alto weather by month is a lot more nuanced than the postcards suggest.
You’ve got microclimates. You’ve got "May Gray." You’ve got October days that feel hotter than July.
Basically, if you show up in January expecting a tan, you’re going to be shivering in a damp hoodie. But if you know how the seasons actually cycle through the Santa Clara Valley, you can time your visit—or your garden planting—perfectly. Let’s break down what actually happens on the ground, month by month, without the fluff.
The Winter Reality: January and February
January is officially the "cool" month. We aren’t talking East Coast frozen tundra cool, but a damp, bone-chilling 45°F at night that makes those old craftsman homes feel like refrigerators.
Highs usually hover around 58°F or 59°F.
It’s also when the rain actually shows up. February is technically the wettest month on average, pulling in about 3.12 inches of rain. You’ll see the hills behind Stanford (the ones with "The Dish") turn a vibrant, almost neon green. If you’re here in early February, keep an eye out for the almond blossoms; they start popping up even when the air still feels like winter, which is a weirdly beautiful contrast.
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- January High/Low: 59°F / 45°F
- February High/Low: 62°F / 47°F
- Vibe: Rain boots, heavy sweaters, and gray mornings that usually clear up by 2:00 PM.
Spring Transitions: March, April, and May
March is the wild card. One day it’s a 70-degree preview of summer, and the next, a late-season storm douses the University Avenue sidewalk cafes. By April, the rain starts to vanish. You’re looking at maybe an inch of total precipitation for the whole month.
Then comes May.
May is when the "marine layer" starts its annual tug-of-war with the valley heat. You’ll wake up to a thick blanket of clouds that looks like it’s going to rain, but it’s just the Pacific Ocean saying hello. Locals call it "May Gray," and it usually burns off by noon. It’s arguably the best time for hiking because the temperatures are a comfortable 71°F—warm enough for a t-shirt but cool enough that you aren't melting on the trail.
Why May is Kinda Great
While San Francisco is getting hammered by wind, Palo Alto sits in a protected pocket. The Santa Cruz Mountains to the west act as a giant wall, blocking the harshest coastal fog. This is why it can be 55 degrees and misty in the city, but a crisp 70 degrees here.
Palo Alto Weather by Month: The Summer Stretch
June through August is the dry season. When I say dry, I mean it. It basically does not rain. Between June and September, you might see 0.1 inches of rain total.
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July and August are the heavy hitters. Highs are usually in the upper 70s or low 80s, but here’s the kicker: the humidity is almost non-existent. It’s that "dry heat" people rave about. You can sit outside at a tech mixer or a backyard BBQ and not feel like a swamp monster.
- June: The "June Gloom" clouds persist in the mornings, but the afternoons hit a sweet 75°F.
- July: Peak summer. Highs around 78°F. The sun is intense, so wear the damn sunscreen.
- August: Technically the hottest month for some parts of the city, averaging 79°F.
The weirdest thing about summer here? The "Natural Air Conditioning." Around 4:00 PM or 5:00 PM, the wind picks up. The temperature can drop 15 degrees in two hours as the ocean air finally pushes over the mountains. You’ll see people at Stanford football games start the first quarter in shorts and end the fourth in parkas.
The Secret "Second Summer" in September and October
If you want the absolute best version of Palo Alto, come in September.
While the rest of the country is thinking about pumpkin spice and falling leaves, Palo Alto is hitting its peak heat. September is often warmer than June. The marine layer finally gives up, and the skies stay a piercing, cloudless blue. October follows suit, staying warm and dry until the very end of the month.
Actually, some of the worst wildfire risks happen during these months because everything is so parched from the rainless summer. It’s beautiful, but it’s also the time when the air quality can get a bit sketchy if there’s a fire north in Sonoma or south in the Santa Cruz mountains.
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- September High: 79°F (often spikes into the 90s)
- October High: 73°F
- Insider Tip: This is when the Stanford Dish hike is at its most brutal. Bring more water than you think you need.
The Cooling: November and December
November is when the light shifts. The days get noticeably shorter, and the first "real" rain usually hits around Thanksgiving. Highs drop back down to the mid-60s.
By December, we’re back to the winter cycle. It’s the second wettest month, and the nights get down to 45°F again. It feels "Christmasy" in that crisp, clean way, but you won’t see snow. Ever. Okay, maybe once every 30 years a few flakes fall and everyone loses their minds, but don't count on it.
Annual Averages at a Glance
To make sense of the Palo Alto weather by month data, look at how steady it stays compared to the Midwest. The "hottest" month is only about 20 degrees warmer than the "coldest" month in terms of daily highs.
| Month | Avg High | Avg Low | Rain Days |
|---|---|---|---|
| Jan | 59°F | 45°F | 10 |
| Mar | 65°F | 49°F | 8 |
| May | 71°F | 54°F | 2 |
| Jul | 78°F | 59°F | 0 |
| Sep | 79°F | 58°F | 0 |
| Nov | 64°F | 49°F | 6 |
Surprising Details: The Microclimate Effect
You can’t talk about Palo Alto weather without mentioning that the city itself has different "zones." If you’re down by the Palo Alto Baylands, it’s windier and cooler because you’re right on the water. If you’re up in the hills near Los Altos Hills or the Arastradero Preserve, it’s often 5 degrees warmer during the day and 5 degrees cooler at night.
Urbanization matters too. All that asphalt in downtown Palo Alto creates a "heat island." It stays warmer late into the evening compared to the leafy, tree-canopied streets of Old Palo Alto.
Actionable Takeaways for Your Visit
- Layering is a religion: Never leave the house without a light jacket, even if it’s 80 degrees at noon. The 5:00 PM temperature drop is real and it is merciless.
- Ignore the "Rain" App: If the forecast says 20% chance of rain in July, it’s probably lying. It won't rain.
- Plan outdoor events for Sept/Oct: These are the most reliable months for clear skies and warm evenings.
- Winter is for the hills: If you like photography, January and February are the only times the hills are green. By May, they turn "California Gold" (which is just a fancy way of saying the grass died).
To get the most out of the local climate, keep an eye on the National Weather Service (KPAO) station at the Palo Alto Airport for the most accurate bayside readings. If you're heading toward the hills, check the Stanford University weather stations, as they reflect the inland valley heat much better. Pack for variety, respect the afternoon breeze, and enjoy the fact that you'll almost never need an umbrella from May to October.