I think nicer weather is a trigger for a lot of people. However, there are also a lot more things to do outside that don't involve alcohol when its nicer out, such as going to the beach and eating an ice cream cone instead of drinking a beer, going hiking on new trails, farmers markets, amusement parks, planting a garden, etc. Its also a great time of year to start an exercise program if you haven't already, I tend to want to drink a lot less when I'm living healthier overall.