Eye of a hurricane
Cyclone Amphan at category 5 strength over the Bay of Bengal at 0745Z May 18, 2020. Amphan made landfall near the India/Bangladesh border on May 20, and was Earth's deadliest and most destructive weather disaster of May 2020. Credit: NASA Worldview.

May 2020 was the planet’s warmest May since record keeping began in 1880, said NOAA’s National Centers for Environmental Information (NCEI) and NASA June 12. NOAA rated May as tied with 2016 for warmest May on record, while NASA put May 2020 ahead of May 2016 by 0.06°C. Minor differences in rankings often occur between NOAA and NASA, the result of the different techniques they use to handle data-sparse regions such as the Arctic.

The year-to-date period of January-May ranks as the second-warmest such period on record, just 0.06°C behind the record set in 2016. According to NCEI’s annual temperature outlook, the year 2020 has more than a 99.9% chance to rank among the five warmest years on record, and a 49% chance of being the warmest year on record. If so, calendar 2020 would mean each of the past seven years would be among the seven warmest years on record.

NASA classified May 2020 as having the 17th-highest monthly temperature departure, or variance, from average for any month in the 1,684-month record, dating back to 1880: 1.02°C (1.84°F) above the 20th century average. All five months of 2020 rank in the top 20 for warmest months on record.

Figure 1
Figure 1. Departure of temperature from average for May 2020, the warmest May for the globe since record keeping began in 1880. Credit: NOAA/NCEI.

Global temperature records are more likely to be set during the peak of the solar cycle and during strong El Niño events, given the extra heat from the tropical Pacific Ocean up to the atmosphere. The remarkable warmth of 2020 has come in the absence of an El Niño event and during the minimum of one of the weakest 11-year solar cycles in the past century, underscoring the dominant role human-caused global warming has in heating our planet.

Global ocean temperatures during May 2020 were the second warmest on record, and global land temperatures were the warmest on record. Global satellite-measured temperatures in May 2020 for the lowest 8 kilometers of the atmosphere were the 2nd warmest or warmest in the 42-year record, according to the University of Alabama Huntsville (UAH) and Remote Sensing Systems (RSS), respectively.

Figure 2
Figure 2. Cyclone Amphan of May 2020 ranks as the 14th most expensive non-U.S. weather disaster and most expensive Indian Ocean cyclone on record.

Three billion-dollar weather disasters in May 2020; 13 for the year

Three billion-dollar weather-related disasters hit the Earth last month, according to the May 2020 Catastrophe Report from insurance broker Aon:

– Nine severe weather events hit China in May, affecting 26 provinces and killing 20 people. Damage was estimated at $1.1 billion.

– After peaking as a category 5 storm with 160 mph winds, a weakening Cyclone Amphan made landfall near the India-Bangladesh border as a category 2 storm with 100 mph winds. The cyclone triggered evacuations of 4.2 million people and destroyed or damaged 2.8 million homes in India and 225,000 in Bangladesh. Amphan killed 133 people and left damages estimated at $15 billion, making it the most-costly Indian Ocean tropical cyclone in history. The large number of evacuations likely led to an increase in spread of COVID-19 in both India and Bangladesh.

– An extensive severe weather outbreak hit Texas and the southeastern U.S. May 27-28. Supercells produced swaths of large and significant hail, notably near San Antonio, with hail up to 2.5 inches in diameter. Damaging winds hit the Houston metro area, with a gust of 65 mph (105 kph) reported in Harris County. Damage was expected to top $1 billion.

Through the end of May, Earth had 13 billion-dollar weather disasters for the year. (The Australian wildfires span the boundary between 2019-2020 and may end up being classified as a 2019 disaster rather than a 2020 disaster.) Three May severe weather outbreaks – two in the U.S., and one in Australia – resulted in more than $900 million in damages, and may end up being billion-dollar disasters once final damage tallies are available later in the year.

Here is the 2020 list of billion-dollar weather disasters through May, listed by dollars of damage, according to Aon:

1. Cyclone Amphan, India and Bangladesh, 5/15 – 5/22, $15 billion, 133 killed
2. Severe weather, Midwest, Plains, Southeast, and Mid-Atlantic U.S., 4/10 – 4/14, $3.1 billion, 38 killed
3. Windstorm Ciara, Western & Central Europe, 2/9 – 2/10, $2.3 billion, 14 killed
4. Wildfires and Heatwave, Australia, 11/8 – 1/17, $2+ billion, 34 killed
5. Severe weather/Nashville tornado, Central and Eastern U.S., 3/2 – 3/5, $2.0 billion, 25 killed
6. Severe weather, Midwest, Plains, Southeast, and Mid-Atlantic U.S., 4/6 – 4/9, $1.9 billion, zero killed
7. Severe weather, Central and Eastern U.S., 3/27 – 3/30, $1.8 billion, zero killed
8. Severe weather, Australia, 1/18 – 1/20, $1.42 billion, zero killed
9. Severe weather, central and eastern U.S., 2/3 – 2/8, $1.25 billion, five killed
10. Severe weather, central and eastern U.S., 1/10 – 1/12, $1.2 billion, 12 killed
11. Flooding, Iran, 2/24 – 4/30, $1.2 billion, 23 killed
12. Severe weather, Plains, Southeast, and Mid-Atlantic U.S., 4/21 – 4/24, $1.1 billion, seven killed
13. Severe weather, Plains and Southeast U.S., 5/27 – 5/28, $1.0 billion, zero killed

The deadliest weather event of 2020 so far has been the ongoing flooding in East Africa from the “Long Rain” season, which runs from March through May. More than 500 people have died in the floods. Kenya and Rwanda have been the hardest-hit, with 237 and 209 deaths, respectively, through the end of May.

Figure 3
Figure 3. Daily cases of COVID-19 in West Bengal, India, have shown a noticeable uptick since the landfall of Cyclone Amphan on May 20, 2020. This increase in disease spread may be the result of 2 million people having been evacuated there in advance of the storm – and in the face of restrictions resulting from India’s virus lockdown. In addition, an influx of migrant workers during the last week of May also likely contributed to the increased spread, according to media reports. A substantial rise in COVID-19 cases in the wake of Amphan was also observed in Bangladesh, where 2.2 million people were evacuated. Credit: Wikipedia.

Neutral El Niño conditions reign

NOAA’s June 11 monthly discussion of the state of the El Niño/Southern Oscillation (ENSO) stated that neutral ENSO conditions existed, with neither an El Niño nor a La Niña event in progress.

Over the past month, sea surface temperatures (SSTs) in the benchmark Niño3.4 region of the eastern tropical Pacific (5°N-5°S, 170°W-120°W) cooled, falling to 0.3°C below-average – short of the 0.5°C below-average threshold for it to be considered La Niña conditions.

Forecasters at NOAA and at Columbia University’s International Research Institute for Climate and Society (IRI) are calling for a roughly 60% chance of neutral conditions continuing through the Northern Hemisphere summer. They put the odds of a La Niña forming during the autumn or winter roughly between 45 and 50%, about the same odds as neutral conditions for the period.

For the August-September-October peak of the hurricane season, they put the odds of El Niño at 6%, and the odds of a La Niña event at 46% (an increase from the 30% estimate a month ago). Atlantic hurricane seasons tend to be much more active during La Niña conditions than during El Niño conditions, because weaker upper-level winds create less wind shear. During La Niña events, the U.S. East Coast from Georgia to Maine experiences much higher landfall frequency than in ENSO-neutral years, according to a 2007 paper.

Figure 4
Figure 4. Departure of sea surface temperatures (SSTs) in the benchmark Niño 3.4 region (in the equatorial Pacific) ending on June 11, 2020. Over the past month, SSTs were about 0.3°C below average-neutral conditions. Credit: Levi Cowan, tropicaltidbits.com.

Arctic sea ice: fourth lowest May extent on record

Arctic sea ice extent during May 2020 was the fourth lowest in the 42-year satellite record, according to the National Snow and Ice Data Center (NSIDC). The record low for May occurred in 2016. Antarctic sea ice extent in May 2020 was modestly below the 1981-2010 average.

Notable global heat and cold marks for May 2020

– Hottest temperature in the Northern Hemisphere: 50.6°C (123.1°F) at Nawabshah, Pakistan, 27 May
– Coldest temperature in the Northern Hemisphere: -40.5°C (-40.9°F) at Summit, Greenland, 1 May
– Hottest temperature in the Southern Hemisphere: 40.2°C (104.4°F) at Kleinberg, Namibia, 5 May
– Coldest temperature in the Southern Hemisphere: -76.6°C (-105.9F) at Concordia, Antarctica, 18 May
– Highest 2020 average temperature to date (1 Jan-31 May) worldwide: 33.3°C (91.9°F) at Yelimane, Mali
– Highest 2020 average temperature to date (1 Jan-31 May) in the Southern Hemisphere: 30.8°C (87.4°F) at Wyndham AP and Marble Bar, Australia

(Courtesy of Maximiliano Herrera.)

Major weather stations that set (not tied) new all-time heat or cold records in May 2020

Among global stations with a period of record of at least 40 years, nine set (not just tied) a new all-time heat record in May, and none set all-time cold records:

Danxian (China) max. 41.1°C (106.0°F), 7 May
Luodian (China) max. 41.2°C (106.2°F), 8 May
Paphos (Cyprus) max. 42.5°C (108.5°F), 17 May
Lao Cai (Vietnam) max. 41.8°C (107.2), 21 May
Hai Duong (Vietnam) max. 39.6°C (103.3°F), 21 May
Hung Yen (Vietnam) max. 40.5°C (104.9°F), 21 May
Montreal Trudeau (Canada) max. 36.6°C (98.9°F), 27 May
Ste Anne de Bellevue (Canada) max. 36.1°C (97.0°F), 27 May
Mount Mansfield (Vermont, U.S.) max. 29.4°C (84.9°F), 27 May

Four all-time national/territorial heat record set or tied in 2020

As of June 12, 2020, three nations had set an all-time national heat record:

Colombia: 42.6°C (108.9°F) at Jerusalen, 19 February (tie)
Ghana: 44.0°C (111.2°F) at Navrongo, 6 May
Cuba: 39.2°C (102.6°F) at Palo Seco, 10 April; broken again on 11 April with 39.3°C (102.7°F) at Veguitas, and again on 12 April with 39.7°C (103.5°F) at Veguitas
Mayotte, France dependency: 36.4°C (97.5°F) at Trevani, 14 April

No all-time national cold records have been set thus far in 2020.

(Courtesy of Maximiliano Herrera.)

55 monthly national/territorial heat records beaten or tied in 2020 as of June 15

In addition to the four all-time national heat records, 55 other national monthly heat records have been set thus far in 2020, for a total of 59 national monthly heat records:

January (13): Norway, South Korea, Angola, Congo Brazzaville, Dominica, Mexico, Indonesia, Guinea Bissau, Gambia, Sao Tome and Principe, Cuba, British Indian Ocean Territory, Singapore

February (10): Spain, Antarctica, Azerbaijan, Costa Rica, The Bahamas, Switzerland, Maldives, Gambia, Russia, Seychelles

March (7): Paraguay, Cabo Verde, Mozambique, Seychelles, United States, Thailand, Northern Marianas Islands

April (13): Paraguay, Niger, St. Barthelemey, Honduras, Guernsey, Haiti, Congo Brazzaville, Kyrgyzstan, Mongolia, China, Saba, Northern Marianas Islands, U.S. Virgin Islands

May (10): Niger, Greece, Saba, Cyprus, Solomon Islands, Turkey, Haiti, Kazakhstan, Chile, Uzbekistan

June (2): Maldives, Thailand

One monthly national cold record has been beaten or tied in 2020:

April: St. Eustatius

(Courtesy of Maximiliano Herrera.)

Hemispherical and continental temperature records in 2020

Highest minimum temperature ever recorded the Northern Hemisphere in January: 29.1°C (84.4°F) at Bonriki, Kiribati, 17 January.

Highest maximum temperature ever recorded in North America in January: 42.0°C (107.6°F) at Vicente Guerrero, Mexico, 21 January.

Highest temperature ever recorded in continental Antarctica and highest February temperature ever recorded in Antarctica plus the surrounding islands: 18.4°C (65.1°F) at Base Esperanza, 6 February.

Highest minimum temperature ever recorded in February in Antarctica: 7.6°C (45.7°F) at Base Marambio, 9 February.

Highest minimum temperature ever recorded in March in the Northern Hemisphere: 32.0°C (89.6°F) at Yelimane, Mali on 23 February.

Highest minimum temperature ever recorded in May the Southern Hemisphere: 31.1°C (88.0°F) at Argyle, Australia on 2 April.

Highest minimum temperature ever recorded in May in Europe: 30.1°C (86.2°F) at Emponas, Greece on 17 May.

Highest minimum temperature ever recorded in May in North America: 35.0°C (95.0°F) at Death Valley, California (U.S.), 28 May.

(Courtesy of Maximiliano Herrera.)

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Jeff Masters

Jeff Masters

Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a...