Highlight: The June 2021 global climate records/climate discussion.
Fig. 1: NOAA/CPC identifies historic weather/climate occurrences in June 2021.
Discussion: Beginning with North America, the late June heat wave across western Canada and the northwestern U.S. was the catalyst to the hottest June on record for the entire continent (Fig. 1). Additionally, the contiguous U.S. observed the hottest June on record.
In the tropics, 4 named tropical cyclones through June tied 2012, 2016 and 2020 for most name storms this early in the season. In the East Pacific tropics, 5 named tropical cyclones tied seven other years for most storms this early in the season. The 9 tropical cyclones observed in June is one shy of the all-time record of 10 set in 1997 and 2018.
After a chilly May, Europe observed their second warmest June on record. In Asia, the second warmest June on record was observed. Not to be outdone, Africa and New Zealand observed their warmest June on record.
Fig. 2: Global 500 MB anomaly pattern for June 2021 to help identify climate factors leading to the record warmth. Chart provided by the International Research Institute for Climate and Society.
Among the catalysts for the record warmth observed across many parts of the globe in June is the elongated subtropical ridging in the northern hemisphere (Fig. 2). The subtropical ridging creates hot weather which is entrained northward into the stronger than normal jet stream pattern. The mid-latitude anomalous warmth is enhanced by large drought areas which explains the record hot June for North America. The near record warmth in Europe was associated with an upper ridge pattern compensating for the upper trough over the northern Atlantic which is associated with a cool pool of ocean water. The cool pool was stronger due to increased ice melt of the polar/Greenland ice which was down 9% from the 1981-2010 average. Meanwhile a stronger than normal jet stream stretched across the mid-latitude southern hemisphere caused by a stronger than normal polar vortex over Antarctica.