The difference is most notable in the daytime in the summer months, nighttime temperatures are more consistent with surrounding observations in the city. In the middle of winter, temperatures at the park are pretty consistent with surrounding areas within the city. In the late spring when trees leaf out, the difference becomes more noticeable. The argument is that the growth over the past couple of decades have made this difference more noticeable. I'm not here to debate whether this is the way it should be or not, but the environment around the park is not the same as it was 30 years ago, let alone 100 years ago.