Friday afternoon, plastic tubs had been dumped among the rows of vines at Devaux Vineyard, a Mumm Napa property off Carneros Highway.

The bright yellow tubs sat on the clumped earth beneath vines that had been baking in the hot sun for the last several days, their fruit rapidly reaching ripeness. No one was about when we zoomed past, banking away from the vineyard and up the hill to the Sonoma County line on the way to the city.

Where was the cooling fog that would allow for a slower, steadier march toward maturity? Not far.

About half an hour later, we were thoroughly chilled as we rolled through the Marin headlands and into San Francisco. Fog was pouring down the hills, racing through the scrub by the shoulder of the road and towards the bay.

We met a friend in the cool, gray city, and about 10 p.m. turned back around. The bridge was still shrouded in fog.

As we neared home, we kept a steady and safe pace. It’s a good thing to do anytime and anywhere, but especially on the Sonoma side of the county line, where a CHP officer is often on the shoulder of the road just waiting for a fool to go by.

We topped the hill, banked down into Napa County and passed Devaux again.

Pickup trucks packed the grassy flat between Carneros Highway and the edge of the vineyard. Transportable light standards beamed an intense, unnatural white light down onto the vines. The yellow bins were on the move. The night harvest — bringing in the grapes after they had cooled from the day’s heat — was on.

Crush is here, and people up and down the valley are going into overtime for a couple of months. Many will lose sleep as they check temperatures and dew points at all hours. Others will hit the road nearly every day: To a Sonoma Coast pinot vineyard, Upvalley to thoughtfully pop a merlot grape into their mouths, onto a challenging dirt track above Yountville to see how things are developing in a hidden valley.

The truck drivers are out, too. Massive flatbeds, with plastic lugs sitting snug on top of each other and lashed to the truck with cloth straps, are moving both directions on the Carneros Highway. Some turn at little-noticed dirt drives that lead to vineyards just out of sight.

On Saturday morning, just over the scraggly wire fence from the off-leash dog run at Alston Park, men in cowboy hats and baseball caps chugged along in tractors, clusters of green grapes showing over the tops of the white lugs in back.

At other times of year, the vehicles populating the Napa Valley wine world include the Indigenous Black Limo, detectable by its specialized licensed plate spelling the name of the company that owns it. Then there’s the Wine Country Convertible Rental, with the top down and the passenger’s bare right arm (and sometimes right leg) hanging out by the rear view mirror.

This time of year, it is all business.