Is Your State Getting Hotter? A Data-Driven Analysis

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Many cities all across the United States have seen their hottest recorded summers within the past ten years. With the highest increase in average temperature occurring in Alaska and the Northwestern region of the United States, it goes without saying that beaches aren’t the only places that get hot in the summer.

In fact, the hottest ten years ever recorded globally have all occurred after 2005. It’s no secret that things have been getting hot everywhere. But since 1970, the surface temperature of the United States has warmed at a much faster rate than the rest of the world.

Living in a city is great, but crowded streets with lots of traffic and buildings that block air flow can not only become uncomfortable during the summer but also dangerous. For many people, the first solution to the heat problem is to crank up the air conditioning. But this fails to see the problem from all angles.

In cities where people are often living in close quarters, running machines that burn more energy have the potential to make the problem worse. So how do we combat the rising temperatures in cities while still remaining conscious of energy usage? Let’s start by taking a closer look at the change over time.

Temperature Changes by State Over Time

While it may seem slight, temperature increases by even a degree are nothing to take lightly. Temperature changes in large areas by only a few degrees can increase the severity of weather events and make it easier for the spread of disease.

Looking at multiple regions around the contiguous 48 states, we took data from the National Climate Data Center’s Statewide Time Series to see how average summer temperatures (June – August) have changed over the past 20 years. Then, looking at the change since 1970 (50 years), we got an idea for the temperature change rate per century. 

New York

New York is home to cities like Manhattan, Queens, Buffalo, and Rochester. Looking at the state from 2000-2020, the average summer temperature has increased at a rate of about 0.5° F per decade. Since 1970, New York has shown a trend that will result in a total increase of 3.8° F across the following century if it proceeds.


Home to Los Angeles, San Francisco, and San Diego, it’s no secret that California has suffered from increased temperatures over the past few decades. Between 2000 and 2020, average summer temperatures in California have increased at a rate of 0.8° F per decade. Looking back further, the state has shown an increase rate of about 5.7° F per century. 


Florida is home to cities like Tampa, Orlando, and Miami. Since the year 2000, summer temperatures in Florida have increased at a rate of 0.7° F per decade. Since 1970, the state has shown an increase rate of about 4.1° F per century. 


Home to Seattle, Spokane, Tacoma, and Vancouver, Washington is the most northwestern state in the continental United States. Looking at summers between 2000 and2020, the state has shown an average temperature increase of about 0.6° F per decade. Since 1970, Washington’s average summer temperature has increased at a rate of 4.6° F per century. 


Lying somewhat on the western side of the country near the Rocky Mountains, Colorado is home to cities like Denver, Aurora, Boulder, and Colorado Springs. Summer temperatures have increased at a rate of 0.2° F per decade since 2000. However, the trend for Colorado since 1970 has shown an increase of about 5.2° F per century.


Major cities in Illinois include Chicago, Springfield, and Rockford, and it seems to be a fairly average representation of the midwestern region in terms of temperature change. Showing a 0.2° F change per decade for average summer temperatures, the rate per century for Illinois since 1970 has been about 0.6° F. 


Texas is home to cities like Dallas, Houston, San Antonio and El Paso, and it covers a very large portion of the southern United States. Although they did experience a terrible ice storm in early 2021, heat has still been rising in the state overall. Average summer temperatures for Texas have increased at a rate of 0.8° F per decade since 2000 and 5.2° F per century since 1970. 

Urban Heat Islands

While trends have shown a general increase in summer temperatures in many areas of the United States, the data often fails to recognize what part cities have to play in this. However, a study from Climate Central on 60 different American cities reveals some insight into how much hotter cities are on average than their rural neighbors. 

Between 2004 and 2014, the cities in this study spent about eight more days at 90° F or hotter than the surrounding rural areas. At times, these cities could be up to 20° F hotter than the rural areas nearby. In fact, the average temperature of these cities also increased by about 0.4° F during the period of the study.

This drastic change between city temperatures and rural temperatures is what researchers call an urban heat island. A heat island is a concentrated zone of hotter temperatures (usually in more developed parts of a city) that is surrounded on all sides by cooler temperatures in suburbs and rural areas. 

There are many things that cause cities to be much hotter in the summer. Crowds, increased car exhaust, and an abundance of concrete and metal building materials all contribute to a poorly ventilated area that traps heat. 

Climate Control Solutions for Urban Environments

As cities start to combat much hotter summers, we are not only seeing traditional methods of temperature control but some new innovations within building design as well. While air conditioning is certainly a part of keeping a space cool, there are more things we as a society will need to consider in order to maintain the comfort and safety of our urban environments during warmer seasons.

Air Conditioning

No matter which way you look at it, some form of air conditioning is almost always necessary for cooling your space during the summer. Because of that, it is often the first step people take to manage heat. 

Whether you are living in a high-rise apartment building, working in an office, or renovating a commercial space, there are a few things you can do to make sure your air conditioning solution is operating at the highest potential. 

  • Change Your Filter. Changing your air filter is essential for maintaining indoor air quality. This is because the dust and particle buildup on the filter will eventually be blown through your vents if not changed regularly. It also affects the way your system is able to cool the space. A filter that goes unchanged for too long will restrict airflow and cause the system to work harder to achieve the same results. This drives up energy costs and makes for an uncomfortable indoor temperature. 
  • Cook food outside. When possible, try to do any cooking outside of the home on the hottest days. Cooking on a grill outside will allow the heat to escape into the air and not into your air-conditioned building. In situations where you do cook inside, be sure your stove hood is working properly to ventilate all fumes up and out of the building. This will help with some of the heat as well.
  • Insulate your AC Unit. Planting shrubs or bushes around your air conditioning unit will provide shade and insulate it from the heat. This means it will not have to work harder, as it would if it was otherwise being hit by direct sunlight. 
  • Dehumidification. Installing a dehumidifier can have surprising cooling effects. When the air inside a room is humid, heat gets trapped and continuously makes the room feel warmer. Dehumidifying your space can remove latent heat from moisture in the air. This moisture also makes your air conditioning system work harder to reach the same cool temperature.
  • Consider a PTAC Unit. For some buildings like hotels or apartment complexes, renovating or installing a new central HVAC system can be expensive not only to implement but maintain in the long run. Many buildings like this will opt for the use of Packaged Terminal Air Conditioners (PTAC units) as a cost-effective way to cool individual spaces and allow for guest control in each room of the building. Just be sure to select the right unit for your needs before installing them in your rooms. 

Airflow and Ventilation

Improved airflow and ventilation can have massive effects on your indoor climate. To do this, many people turn to ceiling fans or box fans, trying to stay cool by manufacturing a breeze. This is certainly helpful, but it’s important to know that fans only push the air around. To make good use of fans, you will need to make sure they are blowing in the right directions. 

It’s best to strive for both horizontal and vertical airflow for indoor spaces. When combined, this cross-directional airflow creates a helix effect that brings cold air up through the floor and allows hot air to spiral up and out of the building. To make this happen, there are two key points of ventilation to consider. 

First, any opening on one side of the building should have a counterpart of the same size on the other side of the building. For instance, you will need to match your 24-inch vent on the eastern side of the apartment by installing another 24-inch vent on the western side as well. This creates an airflow that spans the entire space and prevents interrupted air currents. 

Second, as you make sure your airflow spiralling upward, you will need a place for the hot air to escape. Often, buildings will install a roof vent or an attic fan that actively blows hot air out through the roof. 

Rethinking Building Structures

If you have the opportunity to design a space for optimal climate control before laying the bricks, this is a great opportunity to consider how different building features affect the indoor temperature on hot days. 

A huge factor in this is sunlight. While natural light can sometimes be cooler than heat from a lightbulb, sunlight can really heat up a room during peak times without something to shade the area. Rather than close the curtains, consider installing shutters, louvers, and awnings, especially around windows that are most exposed to sunlight during peak times. This is because structures like this will actually block and reflect the sunlight, whereas curtains and blinds often absorb it. 

In larger buildings, an atrium can help with heat management because it allows plenty of space for upward ventilation. In smaller buildings, creating an indoor void of some kind that opens up into the ceiling can also work. 

Aside from this, there are many buildings that are experimenting with new ways to naturally cool the space. Installations like the Climate Ribbon at Brickell City Centre in Miami and the open air loggias at 277 5th Avenue in New York City are some of the most celebrated innovations in architecture that aim to create a better indoor climate for inhabitants. Because many of these structures cool the air naturally, this can drastically cut down on energy costs. 

Using Different Building Materials

Part of renovating a space for the best effect is considering what type of materials you build with. Many building materials are common only because they are cost-effective and mostly energy-efficient to produce. However, they do not always help with climate control. 

A lot of materials used for roofing tend to be darker. This means that they absorb sunlight for most of the day. That sunlight then filters down into the space, and air conditioners have to work overtime to make things comfortable. A quick solution to this is to paint the roof a lighter color or to outfit the roof with a more reflective material. Some buildings even use a special type of paint made to reflect solar radiation. 

Although it is not the most energy-efficient to create, stone walls will create a much cooler interior. This is because stone has a much higher thermal mass, meaning that it absorbs and releases heat at a slower rate than materials like wood. 

Typically used in the winter months, insulation and weatherstripping are also important for maintaining a cool indoor space for the summer. By making sure your space is well insulated with these measures, you prevent air from slipping out through the walls or under doors. This traps cool air from air conditioners inside your house and keeps hot air from entering. 


Trees and other leafy plants can truly help with cooling a space in a lot of ways. However, many urban areas tend to eliminate trees because of their danger to power lines and their cost to maintain. 

As energy costs become a concern during hotter summers, planting trees can help keep buildings cool by providing shade to both patio areas and windows that let in sunlight. More than that, plants also release moisture that cools the air in a process called transpiration. 


The reality is that cities around the country have been getting hotter. Although the change may appear slight, many people in urban areas have felt the effects. With that, increased heat requires more energy to bring the space to the same level of comfort as before. 

Rather than allow ourselves to be swallowed up by high electricity bills, it’s time that we start looking to more cost-efficient methods for climate control in our cities. We can do some of this by modifying the spaces around us to optimize our HVAC systems and harness natural airflows. 

PTACs can provide great individual climate control for buildings with multiple residents while requiring much less to implement and maintain than a complete ventilation system. Browse our store to see what kind of units might work best for your space.