April northern hemisphere sea surface temperature was 0.63 degrees warmer than 20th Century average: NOAA

While parts of Eastern Canada had a cooler than normal April this year, last month was the fourth-warmest April in 136 years worldwide, the United States National Oceanic and Atmospheric Administration (NOAA) suggested in a recent report.

In its state of the climate report on temperature anomalies, NOAA noted that the northern hemisphere had the ninth warmest April land temperature this year, while the surface of the Atlantic Ocean between Canada and the United Kingdom was at a record low and Australia was about two-thirds of a degree colder than the 1961-90 average last month. [click image below to enlarge]

NOAA provided a breakdown of temperature anomalies, in April, with respect to the 20th century average. It included anomalies of land and ocean surfaces, as well as combined land and ocean averages. It included worldwide data and data for the northern and southern hemispheres.

For land and ocean worldwide, April of 2010 and 2014 had the highest temperature anomalies – of +0.77 degrees Celsius – on record. April 2015 ranked fourth, with an anomaly of 0.74 Celsius. The coolest April was 1909, with an anomaly of -0.54 Celsius.

A temperature anomaly is a departure from a reference value or long-term average. NOAA uses the Global Historical Climatology Network-Monthly (GHCN-M) temperature dataset for land temperatures. For sea temperatures, NOAA uses the Extended Reconstructed Sea Surface Temperature (ERSST) dataset, a “monthly sea surface temperature analysis derived from the International Comprehensive Ocean-Atmosphere Dataset with missing data filled in by statistical methods.”

In the northern hemisphere, April 2015 ranked first for sea surface temperature, with an anomaly of +0.63 Celsius. The coolest was April, 1911, at -0.53 degrees Celsius. For land and ocean temperatures in the northern hemisphere, April 2015 was the fifth warmest April, with an anomaly of +0.87 Celsius. The warmest April was 2014, with an anomaly of +0.94 Celsius while the coolest was 1909 at -0.63 Celsius.

“During April, record warmth prevailed in part of the Gulf of Alaska and other parts of the northeastern Pacific, part of the equatorial Pacific, and a few areas in each of the other major ocean basins,” NOAA stated in its global analysis for April, 2015. “Record cold sea surface temperatures remained in part of the North Atlantic between Canada and the United Kingdom.” [click image below to enlarge]

Worldwide, 2007 had the highest April land temperature anomaly, of +1.52 Celsius. 2015 ranked 10th, with an anomaly of +1.11 Celsius.

“A few areas saw record warmth, including Cuba, part of southern Mexico, small parts of west central South America and southern Brazil, regions of Mauritania, and part of eastern Tanzania,” NOAA stated of land temperatures in April. “Part of north central Russia had April temperatures more than 5°C (9°F) above average …. Cooler-than-average temperatures were notable across large portions of central to western Australia, parts of South Asia, central North Africa, and part of eastern Canada.”

On its map of significant anomalies and events in April, NOAA noted that “exceptional drought persisted” in the Western U.S. while some locations in Finland had temperatures 2 degrees Celsius above average.

South of the equator, Australia had its 29th coldest April in 106 years, at 0.68 Celsius below the 1961-90 average.

“Queensland was the only state or territory to see the temperature rise above its statewide average, at +0.03°C (+0.05°F), while all others were below average,” NOAA stated. “Western Australia reported its sixth lowest maximum temperature on record for the month, at 1.78°C (3.20°F) below average, while the maximum temperature for South Australia was 2.11°C (3.80°F) below average.”