The period from January to April falls into the dry season in Thailand. It is the growing and harvest season for the second rice crop. Maize planting started in April. According to the agroclimatic indicators, Thailand experienced dryer and hotter weather than usual in this monitoring period with below-average rainfall (RAIN -45%), above-average temperature (TEMP +0.2°C) and radiation (RADPAR 5%). As a result of these indicators, a severe decrease in crop biomass production potential was estimated (BIOMSS -15%). 

Maximum temperatures had averaged around 40°C in April, when the national weather service alerted of an upcoming drought, more severe than the big droughts of 2019 and 2020. The government has requested farmers to limit the use of agricultural water during March and April and has issued warnings regarding potential drought damage in late June and early July. The Cropped Arable Land Fraction (CALF) decreased by 3% as compared to the recent five-year average. The ratio of irrigated cropland in Thailand is approximately 22.5%. It is located in the central region of Thailand, where crop conditions worsened due to restrictions on agricultural water use in March and April. 

The NDVI development graph  shows that the crop conditions were generally below the 5-year average during the whole monitoring period. The temperature was mainly above the 15-year average, although the temperatures in late January and early March were lower than unusual. The overall temperature trended upwards, approaching the 15-year maximum in April. The rainfall was high from January to early February and then consistently below the 15-year average. According to the NDVI departure cluster profiles, crop conditions were generally close to average on 32.7% of total arable land, located in the northeast, eastern, and central areas. The 3.1% of total arable land was affected by cloud cover in the satellite images. In the other regions, crop conditions were generally below average and steadily declining.

At the national level, the cropped arable land fraction was 3% below average (CALF 81%). VCIx values were around 0.73. The Crop Production Index (CPI) in Thailand was 0.86. CropWatch estimates that the crop conditions were below average.

Regional analysis

The regional analysis below focuses on the major agro-ecological zones of Thailand, which are mostly defined by the rice cultivation typology. Agro-ecological zones include Central double and triple-cropped rice lowlands (187), the South-eastern horticulture area (188), the Western and southern hill areas (189), and the Single-cropped rice north-eastern region (190). 

Compared to the 15YA, the Central double and triple-cropped rice lowlands experienced hotter and dryer conditions. Radiation (RADPAR +7%) was significantly above average, accompanied by higher temperatures (TEMP +0.2°C) and lower rainfall (RAIN -63%). These conditions led to a below-average estimate for BIOMSS (BIOMSS -18%). The NDVI development graph shows that crop conditions were below the five-year average for most of the monitoring period except for January and February. VCIx was 0.76. Overall, crop conditions were below average.

Indicators for the South-eastern horticulture area show that temperature (TEMP -0.1°C) and rainfall (RAIN -26%) were below average accompanied by higher radiation (RADPAR +3%). This led to a below-average estimate for BIOMSS (BIOMSS -15%). According to the NDVI development graph, the crop conditions were below average during this monitoring period except in early January and early February. The VCIx was at 0.72. All in all, the conditions were unfavorable.

Agroclimatic indicators show that the conditions in the Western and Southern Hills were slightly below average: radiation (RADPAR +4%) and temperature (TEMP +0.2°C) were above average, while the rainfall (RAIN, -38%) was below average. These weather conditions led to a 12% decrease in BIOMSS. According to the NDVI development graph, the crop conditions were below average during the whole monitoring period. The VCIx value was 0.79. Crop conditions are assessed as below average.

In the Single-cropped rice north-eastern region, the rainfall (RAIN, -58%) was below average, while radiation (RADPAR +3%) and temperature (TEMP +0.3°C) were above average. All these agroclimatic indicators led to a decrease in potential biomass (BIOMSS -17%). According to the NDVI development graph, the crop conditions were close to average in January and February and subsequently dropped to below average. Considering the moderate VCIx value of 0.67, the crop conditions were unfavorable.

Figure 1 Thailand's crop condition, crop calendar from January-April 2023

a) Crop phenology map of major crops

b) Crop condition development graph based on NDVI c) Maximum VCI

d) Spatial NDVI patterns compared to 5YA        e) NDVI profile

f) Rainfall profile                                               g) Temperature profile 

h) Crop condition development graph based on NDVI in the double and triple-cropped rice lowlands (left) and single-cropped rice North-eastern region (right) 

i) Crop condition development graph based on NDVI in the South-eastern horticulture area (left) and Western and southern hill areas (right)

Table 1 Thailand's agroclimatic indicators by sub-national regions, current values and departure of 15YA

Table 2 Thailand's cropped arable land fraction (CALF) and current maximum VCI values, January-April 2023