A rapidly strengthening El Nino event in the tropical Pacific could become the strongest on record later this year, and its effects are already emerging in China's unusually complex summer weather patterns, the National Climate Center said.

Sea surface temperatures in the central and eastern equatorial Pacific have risen sharply since El Nino conditions appeared in May. The monitored sea temperature index, which measures three-month running average sea surface temperature anomalies in the central-east equatorial Pacific's Nino 3.4 region, reached 2.09 C above normal in July.

The figure increased 0.49 C from June, and climbed further to 2.64 C in the first half of August, indicating an exceptionally rapid warming trend. The sea surface temperature is likely to peak around November or December.

Given the current pace of warming, the three-month running average is expected to exceed 2.5 C, the threshold for an extreme or super El Nino event, the center said in a statement on its official social media platform.

If the forecast becomes reality, the event could surpass the three strongest El Nino episodes in the observational record — those of 1982-83, 1997-98 and 2015-16 — potentially making it the strongest on record.

China has already experienced weather patterns typical of the developing phase of an El Nino, as rainfall concentrated in two major belts stretching across the country's north and south.

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The western Pacific subtropical high and the monsoon trough have shifted farther north and strengthened, while upper-level cold vortices have repeatedly moved into northern China. The combination has helped produce widespread and intense rainfall in both northern and southern parts of the country.

At the same time, a stronger summer monsoon has contributed to increased typhoon activity and greater storm intensity over the western North Pacific and the South China Sea, which has brought more rainfall to southern China and the lower reaches of the Yangtze River.

Northern China has also experienced repeated heavy rain and strong winds when the northward subtropical high interacted with cold vortices, favoring persistent rainfall. Also, the subtropical high and typhoons have transported moisture northward over long distances.

As a result, China sees a summer marked by overlapping rain-producing systems, broad areas of heavy precipitation and a heightened risk of compound disasters, the center said.

The effects of El Nino could continue into the autumn because the climate system often responds to the phenomenon with a time lag.

During the autumn of an El Nino development year, parts of eastern China, South China and Southwest China typically receive more rainfall, and parts of central China and Northwest China tend to be drier, according to the center.

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Temperatures across much of the country also tend to be above average, with particularly noticeable warming expected in large parts of eastern and central China, Southwest China and the Xinjiang Uygur autonomous region.

The National Climate Center said it will strengthen monitoring and forecasting as the El Nino continues to develop. Particular attention will be paid to changes in its intensity and influence on China's climate, it said.