What film, and how long is long? Mid sensitive (100-400 ISO) black and white or colour negative film does not need particular attention - modern types from Kodak, Ilford and Fuji will all last for a year or more post exposure at room temperature without suffering to a degree that scanning or printing will not fully compensate.
Things are different when it come to slide film for projection use (where minor colour drift will be noticeable).
Many low speed or high contrast films have issues retaining the latent image (Pan F, Velvia 50 and many lithography films are notorious for fading within weeks between exposure and development), while fast film (upward of 400) has a tendency to fog and grow coarse grain when subjected to long storage or heat after exposure.
The rule of thumb would be to process special film soon, and store the rest inside dry containers in a refrigerator if it has to be stored for more than a year or if you are living in tropical conditions.
In general, a plain cupboard at home will often be a better storage than shipping film for development right at the peak of summer - where it will often spend a day or two in a post box or delivery van heated up by the sun.
(Note to the admins - this thread really belongs into film/development/chemistry, move it at your discretion)
