If you planning to travel to Lake Arenal, Costa Rica, 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 11:59 AM. The temperature feels like 71.8 with a humidity level of 93 so dress accordingly. Cloud coverage is 99 percent with visibility at 7 percent. Today’s UV index is 4, don’t forget the sunscreen if you need it! Today’s winds are traveling east-northeast at a speed of 12 MPH. At the end of the day don’t miss the sunset at 11:48 PM.