Night of the Living Dead (1968) - What Time of Year Is It?
In the beginning of the movie, one of the main characters, Barbara, specifically states that it is the first day of Daylight Savings, which would make it Spring. When they reach the apparently well-kept cemetery, the ground is covered with dead leaves giving it a rather Fall-like appearance. Later in the movie, a calendar turned to December is clearly visible in the farmhouse.
I live near where the movie was shot. The farmhouse was abandoned, the family that once lived in it just got up and left one day. Many objects were left in the house. The town nearby condemned the house, and no one went in it. they were about to demolish it when some producer came by, and bought the house. They then shot the movie, and burned it down in the process.
Since daylight's saving is only 2 months removed from Winter... it's very likely the leaves were left there. Living here in Pittsburgh, the site of the movie, April still has somewhat of a fall-like feel. It doesn't start getting warm here until late May.
In the beginning scene at the cemetery, Johnny is trying to get Barbara to hurry it up and says something like "I've already lost an hour of sleep due to the time change". If this isn't a slip-up in itself then this would place the time frame of the movie in the Spring.