When should the timing belt be replaced?

My book shows the recommendation for the timing belt for your 3.5 Honda Odyssey and it says if the vehicle is operated in extreme temperatures (above 110.F or below 20.F) its should be replaced at 60,000 But if the vehicle is NOT operated in those temps the mileage for replacement is 105,000 and you can check this estimate here www.repairpal.com/estimator and locate a shop here www.repairpal.com/directory