September weather trends: What to expect when you’re exploring HCT trails

Summer leaves Cape Cod in September like a slow train, chugging through the green/gold marshes and stopping for anyone who wants to take a swim.

But change is afoot, and the journey between Sept. 1 and the end of the month brings noticeable differences in average temperature and amount of daylight. Just around the corner, you’ll find yourself opening the sweater drawer, filing away your flip-flops and figuring out your Halloween costume.

The good news is that September may be the best month to explore Harwich Conservation Trust properties. Chances are good that temperatures will be right in that sweet spot, from the mid-60s to the mid-70s, allowing for comfortable hikes on our welcoming trails. This allows you to soak in that September beauty, a delicious concoction of changing colors and cool breezes, seasoned with just the right touch of summer celebration and autumn anticipation. These are days to savor.

Warmer than other parts of New England

But why is September weather so great on Cape Cod? Other parts of New England, especially our friends up north, might be dodging frost while we are still picking tomatoes. To help figure things out, we chatted with Caitlyn Mensch, Meteorologist at the National Weather Service (NWS) Boston/Norton office.

The quick answer is that we can thank the still-warmish Atlantic Ocean for our sweet September ride. “The water acts as a temperature moderator this time of year on Cape Cod,” said Mensch. “For a lot of interior places, especially in the valleys, they start to cool down quite a bit more as we head toward fall.”

Our mighty ocean takes a long time to cool down in the fall, adding a gentle touch to weather conditions on the Cape. On the flip side, it also takes a long time to warm up in the spring, a big reason why Cape Cod springs are notoriously late and somewhat chilly.

Frost unlikely but hurricanes possible

The warmer fall weather on the Cape means we usually dodge frost until around the first week of November, said Mensch. That’s a big difference from large areas of northern New England, which can see frost in the third or fourth week of September.

But this September is likely to be warmer across New England, according to the NWS Climate Prediction Center. Most of the region, including Cape Cod, is expected to have a 60 to 70 percent chance of above normal temperatures for the month.

In the stay vigilant department, Atlantic Hurricane Season runs through the end of November. With Cape Cod jutting into the ocean like a boxer’s chin, it makes sense to be on the lookout for the powerful punch of tropical cyclones. In 1954, Hurricane Edna hit the Cape in mid-September, causing significant damage, following in the footsteps of the devastating Hurricane Carol, which plowed into Cape Cod at the end of August the same year.

Shorter days, descending temperatures

Hopefully, we can avoid a hurricane hit and sail through the month unscathed. But there are predictable weather changes for our September scene, nicely summed up by the intriguing WeatherSpark website, which crunches data from weather stations around the world. Here is what they say about what happens as we move through September on Cape Cod:

–Daily high temperatures decrease by 8°F, from 74°F to 66°F, rarely falling below 58°F or exceeding 81°F.

–Daily low temperatures decrease by 8°F, from 61°F to 53°F, rarely falling below 44°F or exceeding 67°F.

–Over the course of September on Cape Cod, the length of the day is rapidly decreasing. From the start to the end of the month, the length of the day decreases by 1 hour, 20 minutes.

–The earliest sunrise of the month on Cape Cod is 6:07 a.m. on September 1 and the latest sunrise is 30 minutes later at 6:37 a.m. on September 30.

–The latest sunset is 7:13 p.m. on September 1 and the earliest sunset is 50 minutes earlier at 6:23 p.m. on September 30.

–The chance that a given day will be muggy on Cape Cod is rapidly decreasing during September, falling from 20% to 5% over the course of the month.

–The average surface water temperature on Cape Cod is decreasing during September, falling by 5°F, from 65°F to 60°F, over the course of the month.

–The growing season on Cape Cod typically lasts for 6.9 months (210 days), from around April 15 to around November 11. The month of September in Cape Cod is reliably fully within the growing season.

A sweet September bucket list

Now that we have the skinny on September, it’s time to get out there and take advantage of all the meteorological magnificence. Perhaps the best thing to do is create a September bucket list: visit every Harwich Conservation Trust property during the month!

For a bit of seasonal inspiration, we leave you with a portion of Helen Hunt Jackson’s lovely poem “September.” Jackson (1830-1885) was born in Amherst, and beautifully captures the Massachusetts vibe of this special time of year:

The golden-rod is yellow;
The corn is turning brown;
The trees in apple orchards
With fruit are bending down.
The gentian’s bluest fringes
Are curling in the sun;
In dusty pods the milkweed
Its hidden silk has spun.

—Check out our handy list of trail destinations with maps, photos and information.

—HCT has fantastic guided programs — see our calendar of events.

—Sign up for HCT eNews, a great way to stay in the loop about exciting HCT events, guided walks and other interesting news.

—Your tax-deductible contributions help fulfill the mission of the Harwich Conservation Trust to preserve land that protects woods, water, wildlife and our shared quality of life. And your land-saving financial support helps us preserve beautiful properties that can become stellar trail destinations. Find out how to donate by clicking here.