Waking up to the foghorn should have been a warning, but I was determined to walk across the Golden Gate Bridge before breakfast.
In my mind's eye I would get halfway across the 2.7km steel structure just in time to catch the sun rising over San Francisco - a perfect photo opportunity. A quick peek out of my unit window put paid to that idea.
Summertime in San Francisco apparently means fog most mornings as warm, moist air from the Central Pacific blows across the cool California current and is sucked into the Bay and the surrounding coastal area.
This morning brought the bonus of light drizzle, too.
Suitably rugged-up against the cold and damp, I dragged a friend along to tackle what is widely recognised as one of the great bridge walks. I'd promised a spectacular dawn, a lifelong memory to relate to the grandkids, complete with the aforementioned pictures. The fog didn't seem to faze her, however.
We crossed under the bridge at Fort Baker, Sausalito. The noise from the morning rush-hour traffic was deafening as commuters made their way from Marin County south, to the city of San Francisco and beyond.
About 120,000 vehicles cross the six-lane bridge every day: four lanes going south in the mornings and four going north in the afternoons - a moveable median barrier separates opposing traffic.
In addition, thousands of pedestrians and cyclists use the bridge daily, separated from the traffic by a steel barrier that was installed in 2003. But before then walkers and riders took their chances with only a concrete kerb for protection. One poor girl, 2-year-old Gauri Govil, even slipped through a gap between the pavement and the road falling more than 50m to her death in 1997. A plaque to her memory can be seen on the Marin side from the sidewalk.
On a damp weekday morning at 6.30 you probably wouldn't expect to see too many people. In bicycle-obsessed northern California the Golden Gate Bridge is both a commuter route and part of a larger circuit for the seriously fit. There were even a few joggers.
Cyclists and plodders share the fairly narrow walkway and there are numerous signs reminding everyone to keep to their respective sides.
Things get really interesting when the gang of road workers trundles to the next spot in need of a coat of paint - we have to press our bodies flat against the barrier to avoid their truck scooting along the footpath.
The crossing takes about half an hour, with one or two stops for a quick snap. The city appears and disappears with the rolling fog, as does the bridge at times.
And, as we pause on the southern end at Fort Point to review our efforts, looking back across the Gate, a ship glides silently out from the fog, under the bridge.
The warning foghorn sounds the city awake.
* Alex Robertson flew to San Francisco with Air New Zealand and was a guest of visitcalifornia.com.