Spring officially begins at 7:44 a.m. today. But as far as Georgia state climatologist David Stooksbury is concerned, the season started three weeks ago.

"March 20 is the date used by astronomers," he said. "But atmospheric scientists use March 1 as the first day of spring."

Stooksbury’s calendar more accurately reflects the phenomena everyone notices: blooming flowers, budding trees, balmy 70-degree days. But the official start of spring has nothing to do with the weather. It’s all about Earth’s position relative to the sun.

Today is the vernal equinox, when the sun crosses over Earth’s equator and the hours of daylight and night roughly are the same.

The days will lengthen until the summer solstice on June 21, when the Northern Hemisphere is tilted closest to the sun. Day and night will be equal again on Sept. 22, the autumnal equinox.

Stooksbury said these astronomical events don’t match up with what’s happening on Earth. For example, the hot part of summer is August, not June.

"There’s a lag time because the Earth’s oceans take a while to heat up and cool down," he said. "So the seasons don’t correlate directly with when we have the most daylight."

Regardless of how you measure the beginning of spring, the signs are obvious and always welcome.

"We’re like a bunch of kids being released from school for recess," said Kat Stratton, director of the Cedar Hill Enrichment Center, a spiritual retreat near Gainesville. "It’s a time of hope for everyone. Everything is so colorful. When I look at daffodils, I feel nothing but happiness."

Last Sunday, the center held a celebration of spring, including a "blessing of the seeds." Stratton said despite our sedentary lifestyles, we respond to spring much as our ancestors did.

"People still feel a connection," she said. "There’s something about being outside and putting your hands in the dirt."

But some people are a little too eager to start planting things.

"They’re really impatient after the long, cold winter," said Beth Stafford, a horticulturalist with Syfan Landscape Center in Gainesville. "But it’s much too early. Our average last frost is April 15. So don’t plant seeds or tender annuals right now. Even if the frost doesn’t kill them, they’ll be weakened by the cold soil."

Hall County Extension Service agent Billy Skaggs offers similar advice.

"The ground is not yet as warm as the air," he said. "It’s not uncommon for us to have nice days in late February and early March, but it doesn’t last."

Skaggs said gardeners often succumb to "spring fever," unable to resist planting.

"I’m encouraging people to hold off for a few more weeks for annuals such as tomatoes," he said. "But this is a good time to plant your cool-weather crops such as root vegetables. And conditions are still favorable for planting trees and shrubs."

But will there be enough rain this spring to keep the plants healthy? Stooksbury said it’s difficult to predict.

"South of Georgia’s ‘gnat line’ or fall line, I’m fairly confident there will be below-normal rainfall from March through May," he said. "I’m also fairly confident that there will be above-normal rainfall in the Tennessee Valley above us. But what happens in between, we’re not sure."

Precipitation so far this year is slightly below normal, but only by an inch or two.

Stooksbury said people shouldn’t be surprised if March and April bring bizarre fluctuations in the weather.

"Spring is a transitional season, so you can expect extremes," he said. "It can snow, or it can be 80 degrees. That’s normal."

Peter Gordon, education director of Elachee Nature Science Center in Gainesville, said he was particularly relieved to see spring arrive this year.

"It was a really cold winter," he said. "Signs of spring are like messages in a bottle, telling us the winter will soon be behind us."

Gordon said visitors take great delight in walking Elachee’s trails this time of year, because almost every day they discover something new in bloom.

"The wildflowers on our trails are already exploding," he said. "And the birds started singing like crazy a couple weeks ago."

Gordon said he noticed the days beginning to lengthen soon after the winter solstice on Dec. 21. "You could see momentum starting to build toward the first day of spring," he said, "and now it’s finally here."