High pressure drives record heat, PV generation across South-East Asia


Large areas of South-East Asia including Laos, Cambodia, and Thailand saw solar irradiance 10% to 30% above the long-term expectation in May 2023. Solar producers in this region benefited from higher than average generation compared to average conditions according to data collected by Solcast, a DNV company, via its Solcast API Toolkit.

The high pressure regime that caused record-high temperatures in large parts of Asia at the end of April has largely persisted into May, with below average rainfall and a slow start to the Monsoon.

In April, many temperature records were shattered in South-East Asia in a heatwave that the World Weather Attribution defined as a “once-in-200-years event that would have been “virtually impossible” without human-caused climate change.” An anomalous high over Siberia persisted in May, with the heat pervading the region: Vietnam’s all-time temperature record was broken in early May, reaching close to 45°C.


The dry weather in South-East Asia was counteracted by cloudier than usual weather in Northern China and South Korea, which generally saw solar irradiance at 80% to 90% of the long-term expectation for May.

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Most of Japan saw broadly typical total solar irradiance for the month of May. However, irradiances were about 10% above average for the northern island of Hokkaido, associated with drier conditions over Siberia.

Total solar irradiance was highest over the Tibetan plateau, where a thinner atmosphere means more sunlight reaches the surface.



Solcast produces these figures via its irradiance forecasting and weather API by tracking clouds and aerosols at 1 to 2 km resolution globally using satellite data and proprietary AI/ML algorithms. This data is used to drive irradiance models, enabling Solcast to calculate irradiance at high resolution, with typical bias of less than 2%, and also cloud-tracking forecasts. This data is used by more than 300 companies managing over 150 GW of solar assets globally.

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