Global Highlights –
The combined average temperature over global land and ocean surfaces for May 2014 was record highest for this month, at 0.74°C (1.33°F) above the 20th century average of 14.8°C (58.6°F).
The global land surface temperature was 1.13°C (2.03°F) above the 20th century average of 11.1°C (52.0°F), the fourth highest for May on record. For the ocean, the May global sea surface temperature was 0.59°C (1.06°F) above the 20th century average of 16.3°C (61.3°F), making it the record highest for May and tying with June 1998, October 2003, and July 2009 as the highest departure from average for any month on record.
The combined global land and ocean average surface temperature for the March–May period was 0.74°C (1.33°F) above the 20th century average of 13.7°C (56.7°F), making it the second warmest such period on record, behind 2010.
The March–May worldwide land surface temperature was 1.26°C (2.27°F) above the 20th century average, the third warmest such period on record. The global ocean surface temperature for the same period was 0.54°C (0.97°F) above the 20th century average, also the third warmest March–May on record.
The combined global land and ocean average surface temperature for the January–May period (year-to-date) was 0.66°C (1.19°F) above the 20th century average of 13.1°C (55.5°F), the fifth warmest such period on record.

Introduction –

With records dating back to 1880, the combined average temperature over global land and ocean surfaces reached a record high for May, at 0.74°C (1.33°F) higher than the 20th century average. This surpassed the previous record high anomaly of 0.72°C (1.30°F) set in 2010. Four of the five warmest Mays on record have occurred in the past five years: 2010 (second warmest), 2012 (third warmest), 2013 (fifth warmest), and 2014 (warmest); currently, 1998 has the fourth warmest May on record. Additionally, May 2014 marked the 39th consecutive May and 351st consecutive month (more than 29 years) with a global temperature above the 20th century average. The last below-average global temperature for May occurred in 1976 and the last below-average temperature for any month occurred in February 1985.

The average land surface temperature for the globe was the fourth highest for May in the 135-year period of record, at 1.13°C (2.03°F) higher than average. The seven warmest Mays over land have all been observed during the 21st century, with the four warmest occurring since 2010. At the hemispheric scale, while the Northern Hemisphere land areas were sixth warmest for that particular region of the globe, the Southern Hemisphere land was record warm for May, surpassing the previous highest May temperature (set in 2002) by 0.17°C (0.31°F).

Select national information is highlighted below. (Please note that different countries report anomalies with respect to different base periods. The information provided here is based directly upon these data):

Warmer-than-average temperatures continued in Australia during May, with the nationally-averaged mean temperature third highest on record for the month, at 1.62°C (2.92°F) above the 1961–90 average. South Australia had a record high average May temperature, at 2.67°C (4.81 deg;F) above average, beating the previous record of +2.57°C (+4.63°F) set just one year ago. Only the state of Tasmania had an average May temperature that did not rank among its 10 warmest; however, it was still 0.90°C (1.62°F) higher than average. Additionally, every state had both above-average monthly minimum and maximum temperatures.
In Austria, May was the first month since May 2013 with a national temperature below the 1981–2010 monthly average, at 0.6°C (1.1°F) below normal.
Spain observed a May temperature that was 1.4°C (2.5°F) higher than the 1971–2000 average. Most of the southern half of the country was 2°–3°C. (4°–5°F) warmer than average.
With records dating back to 1973, South Korea reported its highest average May temperature on record, at 1.2°C (2.2°F) above the 1981–2010 average. The average maximum temperature for the country was second highest in the period of record, at 1.7°C (3.1°F) above average.
In North America, the U.S. state of Alaska had its sixth warmest May since records began in 1918, at 3.56°F (1.98°C) above the 1971–2000 average.
Across the oceans, the global monthly-averaged sea surface temperature was 0.59°C (1.06°F) higher than the 20th century average, marking the highest May temperature on record. The previous high temperature record for May was set in 1998. It also ties with June 1998, October 2003, and July 2009 as the highest departure from average for any month on record. This record high temperature was observed as conditions, although still officially ENSO-neutral, continued to evolve toward El Niño in the east central equatorial Pacific Ocean.

According to NOAA’s Climate Prediction Center, there is about a 70 percent chance that El Niño conditions will develop during the Northern Hemisphere summer 2014 and an 80 percent chance it will develop during the fall or winter. This forecast focuses on the ocean surface temperatures between 5°N and 5°S latitude and 170°W to 120°W longitude.

Information courtesy of – NOAA National Climatic Data Center, State of the Climate: Global Analysis for May 2014, published online June 2014, retrieved on June 23, 2014 from http://www.ncdc.noaa.gov/sotc/global/2014/5 .