The hottest and coldest point of the day is hard to determine. There are many surrounding theories around that subject and it’s unavoidable that there will be some misconceptions and false information that will go around. Those certain spikes in the temperature of the environment will give you a heads up on how hot or cold the day is going to be and when they will be most likely felt. 

Most of us believe that the hottest point of the day is some time early in the morning or noon when the sun is out and the coldest is earlier than that, but actually the truth is, those two points occur later in the day and there is only a short interval between the two. 

We did our own investigation and we have come up with conclusions of our own and some theories we believe could support our claim. 

The time when it is the hottest or coldest in the area largely depends on the location and the season. The heat and light from the sun takes time to reach the earth and the shape of the earth also determines how near or far you are from the sun’s reach. This analogy can also be applied to the temperature changes of the earth. 

Direct sunlight

Noon time is when the sun is at its highest peak above the earth. When all of its light and heat are concentrated on the earth, we call it the solar noon. Being outdoors during this time without appropriate protection could cause severe sunburn even with short exposure, says David Finfrock, NBC 5 weather reporter. The radiation from the sun is at its highest during this point of the day, but that does not always equate to high temperature. 

Diurnal cycle

The diurnal cycle refers to the rotation of the Earth on its own axis, resulting in day and night. This also adds to the variations in temperature on different parts of the Earth’s surface. The delay of the temperature increase is called the thermal response. According to the National Climatic Data Center, the delay could run from three to four hours from the onset of solar noon to thermal response. 

Thermal response

Thermal response starts at solar noon which is when the surface of the Earth heats up. This gradual increase will continue as long as the sun generates enough heat that reaches the Earth. It takes three hours for this process to be noticeable. This also leads us to believe that the hottest point of the day is between 3 and 4:30 in the afternoon during summer time. Of course, this also depends on the amount of clouds and wind speed. 

Other factors

Many factors come into play in the determination of the hottest point of the day. If you live in a country where you have daylight savings time, you may experience it one hour earlier or later than the rest of the world depending on what season it is. Speaking of season, the climate changes in the transition from one season to another is also another factor. During winter time, the cold decreases the overall temperature that we experience in the day. 

So during this season, the hottest time of the day would be early in the morning. The coldest front is later in the afternoon. Geographic location plays a huge role in figuring out what time during the day your area has the highest temperature. 

The hottest time of the day

We all believe that the hottest point of the day is at noon when the sun is at its highest but that’s not entirely true. But the truth is that the hottest point of the day is some time between 3 and 4 in the afternoon. 

Why is it in the afternoon?

Even though the sun is at its peak at noon and gives off the most radiation and heat, the thermal response delay moves that time further around 3 pm. 

brown wooden bench beside leafless tree during golden hour

Basically, this is how thermal response goes: After the solar noon, the energy from the sun begins to decrease gradually. But the heat that the earth has received will still remain as long as it is still getting radiation from the sun. This leads to an accumulation of heat on the Earth’s surface, meaning there is more heat being taken than there is being given off. 

The temperature will still continue to increase until the radiation from the sun dies down just enough for the Earth to release some of the heat back into the atmosphere. 

Late in the afternoon, around 3 or 4 pm is the point when the heat that is built up on the surface of the Earth can be felt and there is still no chance for the earth to release energy back into the atmosphere. You should know that heat transfer takes some time so the time when the sun is at its highest is not yet the hottest point of the day. Energy will travel and there is a delay in the earth’s thermal response. We will feel that change later in the afternoon. 

Solar radiation means the transfer of heat energy from the rays of the sun to the earth. In return, the earth will also need to let some of that heat out but not instantaneously. During that delay, the heat will keep building up on the earth’s surface, causing a rise in temperature.

The delay is called thermal response. And this pertains to the amount of radiation received by the earth at a certain period of time. 

When do the lowest temperatures happen?

Usually, we expect the cold around the evening and deep into the night. But in reality, the air temperature is at its lowest just before sunrise. 

We often associate low temperatures with the night which may make this a little bit confusing. So let’s just put it this way: when you check the weather for Sunday and it states that the high is 50°F (10°C) and the low is 33°F (1°C), the time range of the occurrences of those temperatures are between Sunday evening at 7pm and 7am Monday morning. 

The coldest time of the day

Like we already mentioned, the actual coldest time of the day happens early in the morning just after sunrise. 

Why does it happen after sunrise?

After the hottest point of the day around 3 to 4 pm, the Earth gives off the heat it has accumulated from the sun at a much faster rate while the solar radiation dies down along with the sunset. 

The surface of the earth continues to cool down as the night falls. Just shortly after sunrise, the sun emits solar radiation again and starts to give off heat to the earth but not that strong yet to match the rate of the earth’s surface cooling down and giving off heat to the atmosphere. 

trees under cloudy sky during sunset

When the Earth’s loses heat much faster than it takes in, that is when the day is at its coldest. This happens for a short time after sunrise. The exact time is not the same for all places due to the differences in atmospheric conditions, the location, and the season. 

There are other times when the earth reaches the coldest temperature at a certain point in the day and that can be a couple of hours after the hottest time of the day. This is due to the fact that the earth is losing more heat at a faster rate and the solar radiation from the sun is not anymore enough to keep the surface warm. 

Another time when it is coldest is just after sunrise. Most people won’t agree with this because it does not make sense that the earth would be cold even though the sun is out. But like we said, the energy from the sun takes time to reach the earth and to be absorbed by the earth’s surface. So there is a window there when the earth is already receiving energy from the sun but at a slower rate compared to the pace at which the earth is losing heat. 

You can determine the hottest and coldest time of the day with a lot of factors. But you have to keep in mind that the hottest time of the day is really between 3 to 4 in the afternoon and the coldest can either be a couple of hours after that or just after sunrise. Location and weather patterns can cause some variations so we cannot give an exact time as to when these can be felt.

Conclusion

Without the knowledge of thermal response and solar radiation, we would easily be misled into believing that the hottest time of the day is when the sun is at its highest. Because of the dynamics of thermal energy, the heat from the sun does not instantaneously cause the earth to change temperature. 

When talking about the coldest point of the day, we also would immediately think that it would be around late in the evening when there is no sun. But the truth is, the earth is at its coldest just before it starts to warm up, which is some time after sunrise. Also, we could also experience it just after the hottest time of the day, one to two hours after the hottest point. 

Bottomline, there is no exact time that tells us when the earth is at its hottest or coldest temperature. With the many factors that influence the cooling down and heating up of the earth’s surface, add in the laws of thermodynamics, the location and the mere fact that weather patterns are unpredictable nowadays, you have to key in a lot of variables to be able to get a rough estimate.