Summers never used to be this hot, did they? You may have asked yourself that question and wondered whether in fact you’re just getting more sensitive to the heat as you get older. But in fact, Summers are getting hotter and we’re all feeling the effects.

The rising sun

The US National Centers for Environmental Information sets ‘normal’ temperatures - currently based on 1981–2010 figures - by working out average daily maximum and minimum temperatures for each area.

Climate Central, a US-based climate change research organization, analysed past temperature records for June, July and August across the United States and compared the number of recorded days above normal maximum temperature in 1970 with the same records for 2017, and found a dramatic increase in temperature in both rural and urban locations.

The analysis showed a rise in above-average temperature days and a drop in below-average temperature days across most of the country. That suggests that the average itself is rising.

Image: Climate Central

Of the 244 areas the study looked at, 92% experienced an increase in the number of above-normal temperature days, compared to 1970 figures. The biggest jumps were recorded in Texas, Louisiana and Florida.

Cities like Austin, Texas, experienced over 60 days above normal heat in 2017, compared with below 30 days in 1970. The same trend was seen in New Orleans, Louisiana, with the average virtually doubling from just over 30 days in 1970 to over 60 in recent years. In Miami, Florida, the figure jumped even more dramatically, from under 20 days half a century ago to just under 60 in 2017.

Too much of a good thing

Although holidaymakers and the US tourism industry might welcome a few additional warm summer days, extreme sun and periods of prolonged heat can seriously impact the wellbeing of people, animals and crops.

As wetlands begin to dry, some birds and wildlife are unable to find drinking water. Parched land can also damage agricultural crops and significantly increase the prospect of wildfires.

Intense heat also increases health risks, exposing people to more incidents of heat stroke, respiratory diseases, sunburn and drowsiness. This is particularly true for vulnerable groups like the young, elderly and people with serious medical conditions.

The effects of intense sun is often greater in urban areas, too. As roads, pavements and bricks heat up, air stagnates and cities and towns turn into heat islands surrounded by cooler rural areas.

When temperatures increase so do electricity bills as people seek the cooling effect of air conditioners, which generate more harmful emissions.

So any short-term benefits that come from more warm weather are likely to be far outweighed by the long-term adverse effects.

The US definitions of ‘normal’ temperature will be updated in a couple of years using data from 1991-2020. We can expect to see ‘normal’ temperatures that are significantly higher than they are now.