Size

• It's best to think about the size of the party when choosing the right time of year to hold the celebration. For instance, if you're hosting a large gathering such as a block party or an outdoor barbecue on a weekday, summer is best, since people are likely to be able to get off work for vacation time, and younger guests will be out of school.
  
  

Types

• The best time of year to throw a party also will depend on the type of party you are organizing. For instance, if you're having a holiday party, the end of November or any time during the month of December typically are appropriate. If you're hosting a 4th of July event, it's acceptable to invite guests to a party that will take place the first week of July.
  
  

Significance

• For a party that has special significance, such as a birthday or graduation, the best time of year to have the party is the time nearest to the event's date. For instance, if your husband's birthday is in September, a party in the fall season, preferably on his birthday, is ideal. Graduations usually take place in the summer. If you're not able to have the party on your loved one's graduation day, holding the celebration before the end of summer so that the most guests can attend is an acceptable idea.