California Wine Month is September. It has been since the mid-2000s, when the Wine Institute built a promotional campaign around the one month of the year when the entire state’s wine industry is visibly, audibly, smellably at work — and the California State Legislature made it official, most recently reaffirming the designation by concurrent resolution in the 2023–24 session.
The date was not chosen for symbolic reasons. September is when the grapes come off the vine.
That distinction matters more than it sounds, because it’s the difference between a marketing month and a working one. If you visit Sonoma County in September, you are not visiting a celebration of harvest. You are visiting harvest.
When is California Wine Month?
The whole of September, every year, statewide. There is no opening ceremony and no closing one. Individual wineries, regional associations, and county tourism boards hang their own programming on the designation, which means the “official” calendar is really several hundred independent events that happen to share a month.
For Sonoma County specifically, that timing is nearly perfect and slightly misleading at the same time — and understanding why is the single most useful thing you can know before booking a September trip.
September is the busiest stretch, not the whole season
September is not when Sonoma harvest starts. Picking normally opens in mid-August with the sparkling base grapes — the province of Carneros houses like Gloria Ferrer — and the late-ripening reds run well into late October.
In 2026 it opened earlier still. The first Pinot Noir came off the vine on July 16, the earliest recorded start in Sonoma County in at least four decades, after a record March heat wave pushed bud break forward. The practical consequence for a September trip is that the whole season is running two to three weeks ahead of normal and will finish early too. Before you fix your dates, read our month-by-month breakdown of Sonoma’s harvest season — it carries the full picking calendar and this year’s revised timing.
What that means for a September visit
A working harvest is less romantic than the photography suggests, and more interesting. Picking happens overnight, so the crush pad is already wet by the time you arrive for a 10:30 tasting, and fermenting must leaves a sweet-sour smell hanging over Healdsburg for weeks — the single most evocative thing about September here, and the one thing nobody can put on a postcard.
It also means the production side of every winery is flat out. The winemaker who might have given you twenty minutes in April is on a forklift, and some estates close their crush pads to visitors entirely during peak weeks for straightforward safety reasons.
That’s not a reason to skip September. It’s a reason to book the experiences that are designed for it rather than hoping to stumble into them.
The harvest experiences worth planning around
These recur every year across Sonoma County, in various forms and at various price points. Availability changes annually, so treat this as a list of things to search for rather than a list of things to book blindly.
Crush pad and production tours. The harvest-season version of a standard winery tour, with the difference that the machinery is actually running. Look for wineries that describe a “crush pad” or “production” tour specifically — a regular estate tour in September often just means walking past the same equipment while it sits idle. Dry Creek Valley estates like Truett-Hurst are working through Zinfandel in the back half of the month, which is when the pad is at its loudest and most worth seeing.
Grape stomps. Almost entirely ceremonial — no commercial winery makes wine by foot anymore — but genuinely fun, and reliably the best thing on offer if you’re traveling with kids. Whether stomping grapes in a half-barrel strikes you as charming tradition or theme-park nonsense probably depends on how seriously you take wine in general.
Blessing of the Grapes. A ritual with real roots in Sonoma’s mission-era winemaking history, still performed publicly on the Sonoma Plaza during the Vintage Festival and privately at a number of estates. Short, unfussy, and quietly moving even if you’re not religious.
Harvest dinners and winemaker dinners. The densest concentration of these all year. Long tables, seasonal produce, and the current vintage poured by the person who made it. These sell out earliest of anything on this list.
Barrel tastings and library verticals. Several wineries pair harvest with a look backward — older vintages poured side by side, or unfinished wine drawn straight from the barrel with a thief. Tasting a wine at eleven months old and then tasting the finished version of that same bottling is the single fastest way to understand what barrel aging actually does to a wine. Less crowded than the stomps, considerably more educational, and usually the best value on this list.
Ready to build the list? Browse Sonoma County wineries and filter by reservation policy, tasting style, and what’s open the day you’re visiting.
The recurring September events — and the big one that isn’t in September
Two things are true at once here, and most harvest guides get the second one wrong.
The Valley of the Moon Vintage Festival is Sonoma County’s flagship September harvest celebration, and it lands on the last full weekend of September on the historic Sonoma Plaza. It’s been running since the 1890s, which makes it one of the oldest wine festivals in California. The weekend bundles a grape stomp competition, the Blessing of the Grapes, a 5K fun run through the vineyards and into town, a harvest dinner, and a Grand Tasting held after dark at the Sonoma Barracks pouring from more than forty Sonoma Valley producers — the kind of room where a name like Scribe Winery turns up alongside the century-old estates. Proceeds fund the Sonoma Valley Vintners & Growers Alliance Foundation.
2026 dates: September 25–27, on the Sonoma Plaza. The 5K runs Saturday the 26th. Ticket prices for the Grand Tasting step up on August 1, so early is cheaper.
One practical note on the weekend: the ticketed events and the Plaza programming are separate propositions, and they sell out on different timelines. The Grand Tasting and the harvest dinner go first; the 5K and the daytime Plaza schedule stay available considerably longer. If you’re travelling with a mixed group — some drinking, some not, some under twenty-one — build the day around the Plaza and treat the ticketed events as an add-on for whoever wants them. Confirm the current lineup with the organiser before booking flights around any single event, because the schedule shifts year to year.
The Sonoma County Harvest Fair is not a September event. This is the one people get wrong constantly. Home of the World Championship Grape Stomp, it falls on October 10–11 in 2026 at the Sonoma County Fairgrounds in Santa Rosa. If the Stomp is your reason for coming, book October, not September, whatever California Wine Month implies — our harvest season guide has the full fall event calendar alongside it. The same goes for Healdsburg Crush, the Pinot Noir and sparkling tasting on the Healdsburg Plaza: also October.
If you can only travel once, the honest answer is that the last weekend of September into the first two weeks of October is the sweet spot. You catch the Vintage Festival, the opening of the fall event calendar, and the tail of the red harvest in one window — Cabernet from the warmer inland sites around Geyser Peak is typically the last significant fruit to come off in the county, and in a compressed year like 2026 that window arrives sooner than the calendar suggests.
Planning a September visit without getting caught out
Book earlier than you think. September is peak season in Sonoma County — it consistently lands near the top when we weigh up the best time to visit Sonoma wine country, and the crowds reflect that. Appointment-only wineries fill weeks ahead, harvest dinners fill months ahead, and lodging prices reflect all of it. Our harvest guide carries the month-by-month booking lead times that hold up in a peak year.
Go midweek if you possibly can. Tuesday through Thursday in September gets you the same crush pads with a fraction of the traffic on Highway 12 and Westside Road, and you’re more likely to get a real conversation with someone who has time for one.
Plan for heat, then for cold. Inland Sonoma — Alexander Valley, Dry Creek, Healdsburg — regularly runs into the nineties in September. Coastal and Russian River sites can be twenty degrees cooler and foggy by late afternoon. Layers are not optional, and neither is water. Our guide to fall weather in Sonoma wine country has the month-by-month temperature picture if you’re deciding between September and October.
Fewer wineries, longer visits. This holds year-round but especially during harvest, when the interesting things take time to see. Two properly booked stops beat four rushed ones, every time. We’ve written a fuller version of that argument in our Sonoma wine weekend planning guide.
Know that September is also fire season. It doesn’t need to change your plans, but it’s worth having flexible cancellation terms and checking conditions before you drive. Locals do the same thing.
Want the whole thing mapped out? Build a custom Sonoma itinerary with drive times, reservation requirements, and tasting stops that actually fit in a day.
Frequently asked questions
When is California Wine Month?
California Wine Month runs the entire month of September, every year. It’s a statewide designation recognized by the California State Legislature and promoted by the Wine Institute, timed to coincide with the peak of the annual grape harvest across California’s wine regions.
Is September a good time to visit Sonoma County?
It’s arguably the best time. Harvest is underway, the weather is warm and dry, and wineries run their most interesting programming of the year. The tradeoff is that it’s also the busiest and most expensive month, so book well ahead and expect company on the road.
What is a grape stomp, and can I actually do one?
Grape stomping is crushing fruit by foot in an open barrel — historically how juice was extracted, now almost entirely ceremonial. Several Sonoma harvest events include public stomps, most famously the World Championship Grape Stomp at the Sonoma County Harvest Fair in October.
Do I need reservations to taste in Sonoma during harvest?
For most wineries, yes. Reservation-required tasting is now the norm rather than the exception in Sonoma County, and September fills faster than any other month. Some tasting rooms still accept walk-ins, but arriving without a plan on a September Saturday is a good way to spend the day driving.
Can I watch grapes being harvested or processed?
Sometimes. Picking usually happens overnight or before dawn, so it’s rarely visible to visitors. Crush pad processing is more accessible — look for wineries offering a harvest-specific or production tour, and confirm in advance, since some close the pad to guests during the busiest weeks.