The Nature Reserve, and in particular Isola della Cona, can be visited all year round, and the latter is equipped with easy and adequately marked pedestrian routes.
By car, if you come from Monfalcone, turn left on the road leading to Grado, at the bridge on Isonzo (left bank); go ahead along the dirt road until you will reach a car park, and then continue on foot following the trail markers. Beyond the bank, you will reach the Visitor Center with the shelters for horses.
From here, a trail gives the opportunity to reach in about 15 minutes (and with any kind of shoes), Marinetta Observatory, equipped with an accessible and comfortable ramp for people in wheelchair.
From Marinetta you can go back to the Visitor Center along the same road or continue along a trail which, following the bank surrounding the fields, leads back to the car park along a "circular" route.
Along the same trail, the so-called "Sentiero del Mondo Unito" (Trail of the United World) leads in 30 minutes to Cioss observatory ("cioss" is an onomatopoeic term which in the local dialect indicates a duck very widespread here in winter: the Widgeon).
From here go ahead towards Punta Spigolo for about 80 minutes.