There is actually some science behind why pumpkin spice, sweater weather and cool nights take over your thoughts in the late summer.

Your body is noticing the subtle shift and beginning to prepare you for the season change, even if the temperature doesn't agree.

It's all about 'photoperiodism'

If you have fall on the brain in the middle of an August or September heat wave, it isn't necessarily an effective marketing strategy.

It is called photoperiodism, and it is defined as an organism's ability to use day length, not temperature, as a signal for the change of seasons.

This is because temperatures are significantly less predictable compared to daylight hours. With our four seasons and the rotation of equinoxes and solstices, the amount of daylight each day is predictable. The graphic below has more information.

Your body has learned to notice the changes in sunlight as a sign of a changing season, not the temperatures.

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Which organisms adapt to the daylight changes?

Everything from people, animals, plants and even bacteria is able to adapt to these subtle changes each day.

For humans, it is more that we are looking forward to not having to run the air conditioning constantly. These changes in sunlight can even impact sleep patterns and lead to seasonal affective disorder, or SAD. This happens for many people living in higher latitudes in the winter months because daily sunlight decreases so substantially.

For animals living in high altitudes, photoperiodism is essential for breeding habits.

Certain animals desire to have their babies in certain months, depending on when food is available. All animals, from bears and horses to goats and sheep and even mice, are hyper-aware of the changing seasons to be able to deliver healthy babies at the right time of the year.

What if you live in a city?

In case you were wondering, when you live in a city, photoperiodism still impacts you. It may be reduced due to artificial lights from downtown areas, but multiple studies have confirmed that natural light changes are noticed by humans and the body still prepares for the next season.

How does extreme weather play a part?

An August heat wave can bring record-high temperatures that can persist into September, but it actually increases the urge to fully embrace the next season. People can long even more for sweaters, cool nights and campfires should a late-season heat wave occur.

And it occurs in all seasons, even though we have been primarily talking about fall now. This is why there can be a particularly extreme reaction to the late-season snowstorm.