Warm weather in the spring is a lot different from warm weather in summer. Those first few afternoons in the 70s and 80s always feel luxuriously warm following our long northern winters. However, these days usually come with very low humidity which causes them to cool down quickly after only a few warm hours in the afternoon. More often than not, these early season warm days are also quite windy, adding a little more chill to the feel of the day.
In summer, however, warm days are warm for most of the day due to the higher humidity in the air. Water has a higher specific heat than dry air, which is why humid days have less temperature range from morning to afternoon than in dry weather. Even the early morning hours can be pleasantly warm in summer. Wind is usually lighter in summer as well, especially in July and August.