If you planning to travel to Trefethen Family Vineyard, Napa, California, here is your 6-day travel weather forecast to make sure you have all the essentials needed during your stay. Start your day when the sunrises at 3:24 PM. The temperature feels like 54.5 with a humidity level of 98 so dress accordingly. Cloud coverage is 92 percent with visibility at 8 percent. Today’s UV index is 1, don’t forget the sunscreen if you need it! Today’s winds are traveling east-southeast at a speed of 2 MPH. At the end of the day don’t miss the sunset at 12:53 AM.