The northern hemisphere is experiencing a series of extreme heat events, with record high temperatures and prolonged exceptional heat waves. The city of Phoenix in the United States, for example, is on track to end a month of measuring 43°C or more every day. In California, the temperature in Death Valley reached 53 °C. Miami is facing the longest heat wave in its history.
In Europe, the south of the continent is being hit by a brutal heatwave that is still ravaging North Africa and parts of the Middle East and overheating the waters of the Mediterranean. Spain, Greece and Italy are the most heavily penalized countries. Rome had its highest temperature in its observation history at almost 42°C and southern Italy was approaching 48°C.
In Asia, following national heat records in several countries, China recorded a spring temperature of 52.2°C in the country’s northwest, setting a new alltime national record for high temperatures, months after the Asian country set an alltime national record for low temperatures.
While global temperatures tend to peak towards the end of July, the extreme heat sweeping the planet this month is anything but normal. According to researchers at the World Meteorological Organization, last month was the hottest June on record on Earth, and scientists said the first two weeks of July were the hottest since at least 1940 and most likely before that.
Exceptional heat waves are caused in part by natural climate variability and in part by the continued emission of heattrapping gases, mainly from the burning of fossil fuels. Adding to the complicating factor this year is the return of El Niño, a cyclical weather pattern that tends to be associated with warmer years around the world.
July 2023 will likely be the world’s hottest month in “hundreds, if not thousands, of years,” said lead NASA climatologist Gavin Schmidt. Daily records have already been broken this month, according to tools from the European Union and the University of Maine, which combine terrestrial and satellite data in models to create preliminary estimates.
Spain experiences a dry and hot summer | CRISTINA QUICLER/AFP/METSUL METEOROLOGIA
A woman refreshes herself with bottles of cold water distributed by the Hellenic Red Cross near the entrance to the Acropolis archaeological site in Athens. | LOUISA GOULIAMAKI/AFP/METSUL METEOROLOGIA
Mediterranean countries in Europe hit hardest by heat | TIZIANA FABI/AFP/METSUL METEOROLOGIA
Dee Lee, 34, tries to cool down in scorching heat in Phoenix, Arizona, USA | BRANDON BELL/GETTY IMAGES/AFP/METSUL METEOROLOGIA
Is the extraordinary heat in North Africa, Europe, North America and Asia a sign of the Brazilian summer? This question is extremely difficult to answer due to the climatic characteristics of Brazil and in principle for most areas it is not an indication that there will be exceptional heat between December and February.
Why? The hottest months of the year are summer in these extreme heatstricken northern hemisphere locations, but in parts of Brazil, the highest temperatures of the year traditionally do not occur in summer, but rather at the end of winter and early spring.
The period from June to September marks the socalled dry season in central Brazil and affects the Midwest and Southeast. For example, Cuiabá, a city known for its heat, has its hottest days with extreme values in historical climatology precisely in the dry season.
Goiânia has a maximum monthly mean temperature of 32.7 °C in August, 34.0 °C in September and 33.2 °C in October, but in the summer season the maximum monthly mean values are lower, with 30.6 °C in December, the same value in January and 31.0 °C in February.
Still using the example of the capital Goiás, that the worst heat does not occur in summer, but at the end of winter and in spring. According to statistics from 1991 to 2020, the city had an average of 4 days per year in August, 13 in September and 9 in October, but only one on average in December, January and February. Out of an average of 31 days a year with more than 35 °C in Goiânia, 26 occur only in the period from August to October.
The same applies to Brasilia, where the maximum average values are higher in late winter and early spring than in summer. And also inland from São Paulo. In Franca, the average number of days above 30°C is 12 in September and 12 in October. There are four in December and five in January and February.
This can also be seen in areas of Minas Gerais closer to central Brazil, where the temperature curve is heavily influenced by the dry season. Fall of Triângulo Mineiro. Uberaba has the highest maximum annual averages in September and October, which is repeated in Uberlândia.
A special case is the city of São Paulo. The summer months from December to March are the hottest months of the year on a monthly average, although it is also the wettest time of the year. On the other hand, extreme heat events with days with very high temperatures usually occur at the end of the dry season, in September and October. Not only are São Paulo residents expected to face very hot months, but they are also expected to suffer from extreme heat, especially during spring and summer.
What regulates such extreme heat conditions in large parts of Brazil is the rain. The existence of a dry season and a rainy season. Countries currently experiencing extreme heat in Europe do not have as notable a monsoon (rain) season as midwestern and southeastern Brazil. In summer, the atmosphere is wetter and it rains quite frequently, which tends to counteract larger heat extremes.
In late winter and early spring, when there is typically still little rain and the atmosphere is warming, these extremely high temperatures occur in the Midwest, Southeast, and areas of the Northeast with drier climates or far from the coast.
The highest temperature officially measured in Brazil was 44.8 °C on November 4 and 5, 2020 in Nova Maringá, Mato Grosso, surpassing the also official record of 44.7 °C from Bom Jesus, Piauí of November 21, 2005 of November 5, 2005. Both values did not occur in summer.
Therefore, the greatest warming of the planet with successive and simultaneous heat waves in the ocean and even a strong El Niño later this year could lead to thermal extremes of excessive heat in areas in the Southeast, Midwest, southern Amazon and interior Northeast, especially between September and November, MetSul Meteorologia warns.
The likelihood of aboveaverage and sometimes very acidic average temperatures in the spring and summer months is very high in almost all of Brazil. From south to north. For example, under the El Niño drought, temperatures can be well above normal in areas further north of Brazil, both in the Northeast and in the Midwest and North, particularly in the legal Amazon region.
And where could the summer heat in 2024 be even worse and there be more extremes? Among the largest cities in Brazil, Rio de Janeiro not only has the highest average temperatures of the year in summer, but also the highest temperature extremes in the hot season. The city of Rio could have an overly hot summer in 2024 with many days of extreme high temperatures. The risk will be even greater if the Atlantic Ocean on the Brazilian coast warms up.
However, in no other region of Brazil is there such a high risk that the summer heat extremes of 2023 will be repeated in the northern hemisphere as in southern Brazil. This is because, unlike much of the country, the annual heat extremes in the states further south, particularly Rio Grande do Sul, are not modulated by rain.
Unlike the Southeast and Midwest, where there are very dry months with almost no rain (winter) and others with a lot of rain (summer), in most of southern Brazil there is not much difference in the average amount of precipitation between summer and winter, with a greater regularity of annual precipitation, with the exception of the areas in Paraná.
The summer of 2024 is expected to be very hot in the south of the country, with aboveaverage temperatures. Unlike the 20202023 period, which favored allsummer droughts under La Niña, the coming summer is likely to have more rain and humidity, resulting in a greater number of muggy days with warmer nights and a higher frequency of summer storms.
Although prolonged and severe heat waves are more likely during periods of drought, when dry weather and heat lead to heat bubbles, the risk of heat waves in southern Brazil next summer is high, particularly in Rio Grande do Sul and parts of Santa Catarina and Paraná. Therefore, extremely hot days are to be expected. Extremes aside, even the most persistent very hot weather, on average, makes for a scorching summer.