July 2023 was recorded as the hottest July globally in the historical climate record maintained by the US National Oceanic and Atmospheric Administration. The record temperature marked another significant milestone in a period of increasingly elevated global temperatures and renewed attention on the effects of climate change.
According to NOAA, the average global surface temperature in July 2023 was 2.02 degrees Fahrenheit, or 1.12 degrees Celsius, above the 20th century average. At the time, this made July 2023 the warmest July in NOAA’s 174 year global record. The month also ranked as one of the most unusually warm periods recorded globally.
The record was not limited to land temperatures. Global ocean surface temperatures also reached exceptionally high levels during the month. NOAA reported that July 2023 produced a record ocean surface temperature anomaly of 1.78 degrees Fahrenheit, or 0.99 degrees Celsius, above the long term average. It was the fourth consecutive month in which global ocean surface temperatures reached a record high.
The extreme warmth occurred as El Nino conditions developed in the Pacific Ocean. NOAA said El Nino conditions that emerged in June continued through July, contributing to the unusual climate conditions recorded during the month. The agency also said there was a high probability that El Nino would continue through the Northern Hemisphere winter.
The July 2023 global temperature record is important because July is climatologically one of the warmest months of the year. A record during this period therefore provides a significant indication of the overall state of the global climate system.
However, the original claim that July 2023 was the hottest July ever recorded in the contiguous United States requires clarification. US temperature records show that July 1936, during the Dust Bowl period, had previously been the hottest July for the Lower 48 states, with an average temperature of about 76.8 degrees Fahrenheit.
The US later experienced an even warmer July in 2012. The average temperature across the contiguous United States reached approximately 77.6 degrees Fahrenheit that month, surpassing the previous July record from 1936.
The distinction between global and US records is important when reporting temperature data. A month can establish a global record without necessarily setting a national record for a particular country. Climate records are calculated separately for different geographical areas and time periods.
The record global warmth in July 2023 was observed against a broader background of rising temperatures. NOAA noted that July 2023 was the first July in its record in which the global temperature anomaly exceeded 1.8 degrees Fahrenheit, or 1 degree Celsius, above the long term average.
The high temperatures also affected different regions in different ways. Some areas experienced severe heat, while others recorded temperatures closer to or below their local averages. Global temperature records represent an average across the planet and therefore do not mean that every location experienced record heat.
Scientists closely monitor such records because long term temperature trends provide important information about changes in the Earth's climate. Individual months can be influenced by natural climate patterns such as El Nino, but long term observations are needed to determine broader climate trends.
The July 2023 record was subsequently surpassed globally. NOAA reported that July 2024 became the warmest July in its 175 year global record, with a global surface temperature 2.18 degrees Fahrenheit, or 1.21 degrees Celsius, above the 20th century average. July 2024 was 0.05 degrees Fahrenheit, or 0.03 degrees Celsius, warmer than July 2023.
The continued breaking of global temperature records has increased attention on climate change, extreme heat and the need for improved monitoring and preparedness. Governments and climate agencies use temperature observations to assess risks to public health, agriculture, water resources and ecosystems.
For the United States, historical records also demonstrate that extreme heat is not a new phenomenon. The Dust Bowl era produced exceptional temperatures, including the record July heat of 1936. The record set in 2012 further demonstrated the potential for widespread extreme heat across the country.
The July 2023 data therefore represents an important global climate milestone rather than a US national July temperature record. Accurate distinctions between global, regional and national records are essential when reporting climate statistics.
The continuing rise in global temperatures and the occurrence of repeated heat records remain closely monitored by climate agencies worldwide. The data from July 2023 contributed to the growing body of evidence showing significant changes in global temperature patterns and highlighted the importance of continued climate observation and preparedness.