Astronomically at least, the solstice is the first day of summer. It’s the longest day of the year, when the sun reaches its highest elevation in the northern hemisphere. This year it’s on Friday, June 21.

The naturalists at Big Break Regional Shoreline in Oakley will celebrate it with a sunset walk from 7:30 to 9:30 p.m. It’s a chance to enjoy an evening exploration of the Delta, with lots of wildlife sightings possible.

Meet at the Big Break visitor center at 69 Big Break Road off Oakley’s Main Street. For information, call 888-327-2757, ext. 3050.

*   *   *

Summer’s wildflowers are the theme of a hike from 9 a.m. to 1 p.m. on Sat., June 22 at Black Diamond Mines Regional Preserve in Antioch, led by naturalist Kevin Dixon.

There aren’t as many wildflowers in summer, but they are hardy and beautiful. The hike is likely to be steep; it’s for ages 10 and older, and registration is required. Call 888-327-2757, select option 2, and refer to program 25070.

Black Diamond Mines is at the end of Somersville Road, 3½ miles south of Highway 4. Kevin’s hike is free; the park has a parking fee of $5 per vehicle when the kiosk is attended.

And if snakes are your thing, join naturalist Eddie Willis in a program from 11 a.m. to noon on Sunday, June 23 at Black Diamond Mines. Eddie will show two live snakes, and talk about how to share the trails with snakes in the wild. Meet Eddie near the parking lot at the end of Somersville Road.

For general information about Black Diamond Mines, call 888-327-2757, ext. 2750.

*   *   *

The Over-the-Hills Gang is an informal group of hikers ages 55 and older interested in nature study, history, fitness and fun. Everyone is welcome.

Naturalist “Trail Gail” Broesder will lead the gang on a hike from 10 a.m. to 12:30 p.m. on Tuesday, June 25 at Point Pinole Regional Shoreline.

Besides its unusual history, Point Pinole is a beautiful refuge from summer heat. Meet Gail in the parking lot at the end of Atlas Road in Richmond. For information, call 510-544-2233.

*   *   *

Looking further ahead on the calendar, the Fourth of July falls on a Thursday this year. Two of the regional parks plan to celebrate it in style.

You can join the interpretive staff at Crab Cove Visitor Center in Alameda and participate in the town’s Fourth of July parade, from 9:30 a.m. to 1 p.m.

“Swim” along the parade route with the park’s Mobile Visitor Center, or just enjoy the show from the sidewalk.

Then from 2 to 5 p.m. on July Fourth, Crab Cove will host open house at the center, which is at the end of McKay Avenue off Alameda’s Central Avenue. There will be family friendly activities throughout the afternoon.

For information on the parade and open house, call 510-544-3187.

Ardenwood Historic Farm in Fremont always stages an elaborate Independence Day celebration, and this year is no exception.

From 10 a.m. to 4 p.m. on July Fourth, the park plans a 1900s-style community festival with patriotic music on the lawn, fiddle music in the farmyard, and games, contests and races. Try your hand at nail driving, egg tossing, watermelon seed spitting, the bucket brigade, and tug-of-war. Bring a picnic and spend the day.

Ardenwood is located at 34600 Ardenwood Boulevard, just off Highway 84. Fee for the Independence Day event is $10 for adults, $8 for seniors ages 62 and older, $5 for children 4 through 17, and free for kids 3 and under. Parking is free. For information, call 510-544-2797.

*   *   *

Ned MacKay

Posts by Ned MacKay