Light bulbs have a relatively short life, and exterior bulbs have the added disadvantage of being out in the elements, and are always the potential target for juvenile vandals in the neighborhood. This is why it's a good idea to replace each exterior light bulb at the start of each summer.
A great way to remember to change exterior light bulbs is to pick at date and stick with it. We live in a 4-season climate, so we chose June 1st as the day we do certain things around our house. Changing exterior light bulbs is one of those home security tasks.
Some homeowners choose to remove certain bulbs when winter sets in, but this is a highly discouraged practice in the home security community. Exterior lighting needs to be in use 365 days per year. So, simply change each light bulb at the start of each season and unless something out of your control causes one to break or stop working, they should last until the beginning of the following season.
Reinforce this great home security practice with a monitored ADT home security system and do your part to keep burglars away from your home.