Surf in Sri Lanka in July is the peak season month for Arugam bay. If you're planning to visit arugam bay by this time, it's advisable to have a prior arrangement for a room. Staying at Peanut farm, or Whiskey point is recommended since the main point can be hectic. You can also make a day trip to Okanda point break.
Many also prefer to stay in the South coast (Mirissa area) during this time, since the rainfall has stopped and to avoid the crowd in Arugam bay or Pasikuda. South coast also offer upper standard accommodation and great discounted rates. Beginner surfing is possible all through out the year in Weligama beach break.
If you visit Sri Lanka in July, festivities-wise there are the followings,