Climate bulletin - June 2017
Summary of the world's climate in June 2017
The global average temperature for June 2017 as estimated from the HadCRUT.126.96.36.199 data set was 0.64±0.14°C above the 1961-1990 average. Globally, June 2017 was one of the fourteen warmest Junes on record but most likely the third warmest. Global temperature data sets maintained by NASA GISS, NOAA NCEI, Berkeley Earth and C3S also show that June was a very warm month globally. June was nominally between 3rd and 5th warmest in these data sets. Sea-surface temperatures in much of the tropical Pacific were near or slightly above average indicating neutral ENSO conditions.
The global average land temperature for June 2017 was 0.98 ± 0.26°C above the 1961-1990 average. For global land areas June 2017 was nominally the 4th warmest June on record and very likely one of the top eight. Unusual warmth – temperatures exceeding the 90th percentile for the month – was recorded across: large areas of Europe and North Africa, parts of the Middle East, East Africa, east Asia, Brazil and the western US. Few areas were unusually cold with temperatures below the 10th percentile. These were: northwest Russia and parts of Finland, parts of China, and a number of stations on the coast of Antarctica.
A heat wave affected many areas of western and central Europe between the middle of the month and its end. The highest temperature recorded in the UK during a spell of high temperatures from 17 to 21 June was 34.5 °C, at Heathrow Airport on the 21st. This was the UK's highest temperature in June since 1976. A number of European countries reported high average temperatures for the month. Spain had its warmest June on record by a small margin. For Portugal it was the third warmest (after 2004 and 2005). In the Netherlands, this June tied as the warmest with June 1976. For France, Switzerland, Austria, the Czech Republic and Slovakia it was the second warmest June. In each of these cases 2003 was warmer, in some cases by a large margin. More detail on the European heatwave is available in the monthly bulletins from Deutsche Wetterdienst.
The global average sea-surface temperature for June 2017 was 0.54 ± 0.08°C above the 1961-1990 average, nominally the fourth warmest on record and very likely one of the eight warmest. Sea surface temperatures in the tropical Pacific were near average with some areas warmer than the long-term mean, indicating neutral ENSO conditions. Areas of unusually warm SST covered similar areas to May, including: large areas of the North Atlantic and tropical Atlantic; the Indian Ocean (except for the area to the west of Australia and Indonesia); areas of the Pacific, particularly west of the dateline and around 30°N and 30°S. Although a number of areas were cooler than average, unusually-low SSTs were recorded only in limited areas which included: an area to the southeast of Newfoundland and an area to the west of Australia and Indonesia. Another area of below average SST – where historical coverage is too low to accurately assess the significance of current anomalies – was an extended area in the Atlantic sector of the Southern Ocean which has persisted for several months and has been spreading slowly east.
As in May and April, there was a band of cooler-than-average waters in the North Pacific at around 45°N surrounded by areas of warmer-than-average waters. This pattern is characteristic of the positive phase of the Pacific Decadal Oscillation (PDO). Some measures of the PDO have been indicating a shift to its positive phase since the start of 2014. However, on short time scales, SST patterns associated with the PDO look very similar to those associated with El Niño. As ENSO conditions are currently neutral, this suggests a more persistent shift to the positive phase of the PDO. The negative phase of the PDO has been associated with a reduction in the rate of global temperature increase since the start of the millennium.
The series of Ocean heat content produced by NCEI has been updated to June 2017. To depths of 700m and 2000m, Apr-Jun 2017 had the highest heat content anomaly on record for the quarter. The quarterly 700m series begins in 1955 and the 2000m series in 2005.
Higher than average precipitation totals (based on the monthly first-guess analysis by the Global Precipitation Climatology Centre, GPCC) were recorded across: eastern parts of the US and southern Canada. The UK had its sixth wettest June in a series since 1910. It was the wettest June for Scotland in the same period. Denmark, northern Germany and parts of southern Norway were also wetter than average. A band from southern China, across Bangladesh and northern India saw some areas with unusually high rainfall totals. Parts of Indonesia and Papua New Guinea as well as northern Japan were also wetter than average.
ACMAD reported above average precipitation over the southern Sahel and the Gulf of Guinea. Drier than average conditions were reported for Gabon, Ethiopia, Uganda, western Kenya and northern Tanzania. In Australia, many areas in the south of the country were record dry and it was the second driest June overall for the country since 1900 (1940 was the driest). Some parts of the North Island of New Zealand had a record dry June. The Korean peninsula, parts of Columbia, Venezuela and Brazil, and parts of central and eastern Europe were also dry. Portugal experienced unusually low rainfall and, based on the Palmer Drought Severity Index, 80% of the country was in severe drought by the end of the month.
Based on data from the HadISST.188.8.131.52 data set and from the National Snow and Ice Data Center, the Northern hemisphere (Arctic) sea ice extent in June 2017 was likely to have been between the 4th and 7th least extensive in the satellite record. There is some uncertainty in the ranking as a number of years have very similar extents. Southern hemisphere (Antarctic) sea ice extent was nominally the 2nd least extensive June on record in both data sets. Sea-ice extent in the Antarctic has been unusually low since late last year. For more details and analysis of the ice extents including updates throughout the summer, see the sea-ice monitoring brief.