When Mr. Whitey looks up at the dark silhouette of a kayak against a sun-lit sky, his micro-sized brain does not always decipher that the plastic boat isn’t something to eat.

Or that the person in a wetsuit is not a shark mint.

That’s when that biting thing can happen. Darn. And here we were having such a good time.

I admit, the possibility scares me.

In the next two months, all the factors seem aligned for increased chances of great white shark encounters and attacks off the Bay Area coast.

El Niño factor: This past week, 17 miles off San Francisco, the ocean temperature hit 63.7 degrees, some 7 to 10 degrees warmer than the average for mid-August over the past 10 years. El Niño, in the years when there’s plenty to eat, can bring in the big sharks from across the ocean, with peak numbers from mid-September to early October.

Marine riches: The local coast, from the Gulf of the Farallones Marine Sanctuary south to Monterey Bay, has produced unexpectedly bountiful marine riches this summer. At times, krill, anchovies and mackerel have covered miles of water. This can attract every fish-eating critter for hundreds of miles to local waters. Mr. Whitey is at the top of the food chain.

Way more sharks: For years, based on estimates in the ’90s, we assumed there were about 200 to 400 great white sharks at any one time off the Bay Area coast, and in turn, the state listed them as a protected species. A recent study by 10 scientists, published in a scientific journal, says there are now more like 2,400 great white sharks off the Bay Area coast.

So far, there have not been more attacks than in past years (and we’ll get to that). But they happen.

At Bean Hollow on the San Mateo County Coast, kayakers twice had their boats bit by great white sharks. Same thing happened out of Santa Cruz, where the boat, a Hobie, got mangled pretty good. None of the paddlers were hurt.

In the past few years, sightings have occurred many times off mainstream beaches. At Ocean Beach in San Francisco. Linda Mar in Pacifica. Off Montara. And in Marin, every late summer and fall, as predictable as the beat of a metronome, they show up at Duxbury Reef and Stinson Beach.

Same thing at the Southeast Farallon Islands. You can troll a 10-foot carpet on the surface and a big shark can come up for a bite. After all, Mr. Whitey isn’t the smartest guy around.

The abundance of sea lions, elephant seals (especially juveniles) and other marine mammals lowers the odds of getting picked out. That’s why there hasn’t been an increase in attacks in the past 10 years.

Yet you can’t blame micro-brain and 400 million years of munch-time imprinting when he makes the occasional mistake.

Don’t tell those of us on the water about the low odds of getting nailed — keep “more likely to get hit by lightning,” etc., to yourself. The lottery math doesn’t make you feel any more secure out there, believe me.

Giancarlo Thomae

This year, the first-ever rookery of great white sharks — that is, a herd of 14 juveniles — was documented in Monterey Bay (a big one was also sighted by helicopter). This was near the cement ship at Seacliff State Beach. One local hero was sighted slipping into the water with a GoPro camera to try to film them. Turns out he was probably safe. Juvenile great white sharks don’t feed on marine mammals (or usually bite people), but rather fish.

Last Sunday, Kim Chambers became the first woman and fifth person in history to swim from the Farallon Islands to San Francisco. A week earlier, a friend of Chambers, Simon Dominguez, tried to swim from San Francisco to the Farallones and was stopped three miles short when he was circled by a great white. Dominquez said his neck was bleeding a bit from a crack in the skin from prolonged exposure to saltwater. He wisely jumped aboard the support boat.

According to Jean-Michel Cousteau, a great white shark can smell one drop of blood from about 600 yards and its ability to detect subtle electric fields produced by prey is 5 million times greater than humans’.

Field scout Bart Selby said that next month he might attempt to kayak from the mainland to the Farallones. While he was training this month, a friendly 20-foot orca surfaced next to his 17-foot kayak in Pillar Point Harbor.

There have been a lot of things this summer, such as that orca inside the harbor, that have rarely been seen before on the Pacific Coast.

The next two months, nobody knows for sure what is going to happen out there. Except that Mr. Whitey is coming to the party.

Tom Stienstra is The San Francisco Chronicle’s outdoors writer. E-mail: tstienstra@sfchronicle.com. Twitter: @StienstraTom