Fairmont Sonoma Mission Inn & Spa

What to expect

Fairmont Sonoma Mission Inn & Spa is a large wine country resort on Highway 12 in Boyes Hot Springs, a small community just north of the town of Sonoma. It is not a natural pool in the woods. It is a full-service hotel with a pink stucco, red-tile-roofed main building from 1927, a members’ golf club and a 40,000-square-foot spa. What makes it relevant here is the water: the spa pools run on geothermal mineral water pumped from beneath the property, the same hot springs that drew people to this spot long before the hotel existed.

Historic Hotels of America says the current source flows from about 1,100 feet below the resort with a surface temperature of 130°F54°C. Fairmont says the water carries more than 27 naturally occurring minerals. The pools are far cooler than the source. The only pool temperature Fairmont publishes is the Watsu pool at 98°F37°C.

The spa is adults only (18 and older) and it is popular. On weekends the pool decks fill with hotel guests in robes and day visitors, and treatment slots go early. Midweek is calmer.

The pools

Fairmont’s own pages count the pools differently in different places (five geothermal mineral pools in one spot, six resort pools in another). The layout, as Fairmont describes it:

• Roman Bathhouse: two indoor mineral soaking pools, the Roman-style mineral pool and the Roman hot pool, plus a eucalyptus steam room, a halotherapy (salt) sauna, an exfoliating shower and cool-down showers.
• Spa pool: an outdoor pool under tall redwoods with loungers, daybeds and private cabanas.
• Watsu pool: heated to 98°F37°C and used for in-water bodywork.
• Resort pool: the main hotel pool, with the Water Tower Bar and cabanas. This is the family pool and sits outside the adults-only spa.

The bathing ritual is the signature routine. It runs in 10 steps: a grape seed exfoliating shower, 5 to 10 minutes in the salt sauna, a 1-minute cool shower, 10 minutes in the Roman mineral pool, another cool shower, 5 to 10 minutes in the aromatherapy steam room, another cool shower, 5 to 10 minutes in the Roman hot pool, a last cool shower and then at least 10 minutes resting in the relaxation room. Allow 30 to 40 minutes. Fairmont says the ritual is not suitable for expecting mothers and posts heat warnings at the steam room, sauna and spa pool.

Prices and booking

Fairmont publishes these 2026 spa access rules:

• Hotel guests: $69 per person, per day.
• Non-resort guests: $99 to $199 per person, depending on the date.
• Fee waiver: spa access is waived when you book a service Monday to Thursday that meets the minimum service value, excluding holidays and blackout dates.
• Weekend treatments: non-resort guests booking a service Friday to Sunday pay a $59 access charge on top of the treatment price.
• Reservations are required.

Day passes without a treatment are sold through ResortPass, which also lists main pool passes, daybeds and cabanas. Prices there move with demand. Sonoma Magazine reported passes starting at $53 in 2024, but expect higher rates on weekends and in summer. Spa cabanas include spa day passes for up to four people, and whirlpool cabanas come with a private geothermal tub.

Spa hours are 9am to 7pm Monday to Thursday and 9am to 8pm Friday to Sunday. Arrive 30 minutes before your first appointment, fill in the medical history form 24 hours ahead, and cancel at least 24 hours in advance or pay the full treatment price. Phones are discouraged, outside music is not allowed, and outside food and drink are banned in the spa.

Hotel costs to plan for: a $59 nightly resort fee plus tax, self-parking at $29 per day or valet at $49 per day. Day visitors pay $3 per hour to park, with the first 3 hours validated when using the spa or dining. Check-in is 4pm and check-out 11am.

Getting there

The resort is at 100 Boyes Boulevard on Highway 12 (Sonoma Highway), about 2.5 miles north of Sonoma Plaza. From San Francisco, take US-101 north across the Golden Gate Bridge, then Highway 37 east and Highway 121 north into the Sonoma Valley, and follow Highway 12 through Sonoma to Boyes Hot Springs. Fairmont puts San Francisco International at 58 miles and about 1 hour 20 minutes away, Oakland International at 59 miles and Sonoma County Airport at 27 miles. Napa is about 17 miles east. A bus stop named for the inn sits on Highway 12 right outside.

When to go

The resort is open all year. Summer and the autumn grape harvest are the busiest stretches in Sonoma Valley, and weekends book up first. Winter and early spring bring cooler, often rainy days, which is the best weather for hot mineral pools and the season when midweek rates and the Monday to Thursday fee waiver are easiest to use. If you want the outdoor spa pool quiet, go on a weekday morning.

History

Native American communities used the hot springs here long before settlement. In the 1840s, Dr. T.M. Leavenworth named the property Agua Rica. Captain Henry E. Boyes bought it in 1883 and, according to Historic Hotels of America, struck hot water of about 112°F44°C in a 70-foot well in 1895. He opened the Boyes Hot Springs Hotel in 1902. The hotel was destroyed in 1923, and the rebuilt resort opened in 1927 and was renamed Sonoma Mission Inn the next year. During World War II the Navy leased it as a rest center for servicemen. Fairmont has managed it since around 2002.

Where to stay nearby

The inn is the lodging, with 23 room and suite types listed. The town of Sonoma, 2.5 miles south, has smaller inns and hotels around the plaza within a short drive. For camping, Sugarloaf Ridge State Park, north of Kenwood off Highway 12, is the closest public campground in the valley.

Safety notes

• Heat: The bathing ritual alternates hot rooms and cold showers for a reason. Keep each heat session within the posted times and drink water.
• Pregnancy and health: Fairmont says the ritual is not suitable for expecting mothers and asks pregnant guests to be past 12 weeks for services. Talk to a doctor if you have heart or blood pressure concerns.
• Alcohol: The spa advises against drinking before or after treatments, which is worth remembering in wine country.
• Accessibility: The resort has 10 ADA rooms, and ADA pool lifts serve both the resort pool and the spa pools.