Cooler weather for day hiking, etc.
Portsmouth harbor cruises are still quite fun as the weather cools off.
I recommend hiking at Pawtuckaway State park, around the backside which is accessed from route 107 and reservation road, a bit south on 107 from Deerfield Parade, heading toward Raymond. the sign for the mountain trail was knocked down some years ago, Look for the trinagle shaped intersection on your left, 1/2 mile before you pass under the power lines.. It can be tough to find the road. trail maps are available;
Map of [1-84] Reservation Rd Deerfield, NH by MapQuest can help you pinpoint reservation road
trail map online;http: /www.nhstateparks.com/Maps/pawhiking.html
Access from the backside of the park is free and is quite popular with serious mountain bikers and, beginning rock climbers on the boulder trail. Double dotted lines shown on the map can be driven in any vehicle. using the boat ramp+ parking on the north side of the lake is ideal for accessing the Shaw Trail to access the south mountain is a great day-hike. Its quite hilly and routes you through a swampy area [dry hiking though]so bring the mosquito spray.

The view from the fire tower is wonderful fall foliage viewing from his 900' mountain. The hike up the mountain is moderate as hiking challenges go. Perhaps 30 minutes to the top from the base at the #6 balloon on the map.
If you're around Durham, theres a short hike on the edge of the bay, at Adam's point on bay road at the UNH marine lab, It's its a 1/2, ~3/4 hour walk around the peninsula at the edge of the bay. go to the end of adams Point Rd. + park. website;
SeacoastNH.com - Adams Point
map:
Map of [300-375] Bay Rd Durham, NH by MapQuest
FYI, do not try + use the boat ramp, its too shallow to actually launch a boat, use Hilton Park in Dover Point instead.