Hongkongers may not have noticed it but the average global temperature last month tied with 2010 for the warmest April on record.
The mean temperature of sea and land surfaces combined was 14.47 degrees Celsius, an increase of 0.77 of a degree from the 20th-century average of 13.7 degrees, the US National Oceanic and Atmospheric Association said.
Reflecting a warming global climate, it marked the 38th consecutive April and 350th consecutive month with a temperature above the 20th-century average.
In parts of chilly central Siberia the reading was five degrees above the 1981-2010 average.
In Hong Kong, however, the April average of 22.6 was within the normal range, said Tong Hang-wai, a scientific officer with the Hong Kong Observatory.
Climate scientists have been monitoring changes in ocean and land temperatures to track climate change, the effects of which, they say, are being felt in irregular weather patterns, heavier rainfall, droughts and floods.
As sea temperatures rise, an increase of a single degree above its usual range can cause coral to bleach and die. It also affects the range and type of species caught in coastal areas as fish and other marine organisms adapt.
The last April with a below-average temperature was in 1976, just a year after the Vietnam war ended. The last time any month had a global temperature below the 20th-century average was 29 years ago in February 1985, when Back to the Future became the highest grossing film of the year.
At 1.12 degrees higher than the 1961-1990 average, Australia had its seventh-hottest April since records began 105 years ago.
But the spike was not uniform across the globe. Most of the United States and Canada experienced cooler than average temperatures for the month.
In the same summary, NOAA put the chance of the El Niño weather phenomenon developing in the northern hemisphere this summer at greater than 65 per cent.
While floods and droughts are expected elsewhere, an El Niño is expected to delay Hong Kong's typhoon season and increase rainfall in winter and spring.