Bay Water Too Cold For You? Blame The Wind

KPIX 5 Morning Weather Anchor Roberta Gonzales answers the questions you never get to ask on-air.

Q: This morning, a meteorologist (not CBS) said that the Golden Gate buoy temps indicate what's happening with the weather. But as bay swimmers, we know that the buoy temps change depending on tide — whether the readings are taken during an ebb or a flood.

Ebb tides warm up the bay; floods cool it, especially when there's upwelling. We've seen wide fluctuations of 4-5 degrees throughout the course of a day at the GG buoy, but the bay temps we swim in more consistent. Throughout the winter, the bay was 4-5 degrees warmer than normal — warmest we've experienced ever. Now it's about 2-3 degrees colder than normal for this time year. What happened? ~ Warmly, Roberta Guise

A: Great observation about the Ebb and the upwelling! That's' what I love about "experiencing" our Bay Area. Because you are a swimmer, you are more aware of bay currents and conditions!

What appears to be happening is winds that normally blow from the north, trapping warm water closer to the equator, have slackened since the summer. That's allowed the warm water to move north and during our winter months, you are correct, our bay waters were warmer than ever!

In most years, the winds also help push ocean surface waters, churning up cold water from down below. That process, called upwelling, did not happen as much over the winter.

Usually, if the wind is light, the water does not cool. It was a wind-less winter with me riding my bike on any given day without a head wind. Today, the wind is howling over the ocean, where a Small Craft Advisory is in effect until 3am Wednesday.

Onshore winds will blow west 10-20 with gusts to 35 mph. Tonight, winds increase 20-30 mph. Water temperature outside the Gate has dropped to 50 degrees, while inside the bay the water temperature ranges from 55 to 58 degrees. Brrr!

I would love to hear from you! Please send weather questions, observations and photos to me, Gonzales@kpix.cbs.com and I look forward to hearing from you!