The Japan Meteorological Agency announced the “Weather Forecast for July 2024” on Thursday, August 1st, revealing that Japan’s monthly average temperature for July reached the highest level since records began in 1898, surpassing last year’s record. August is also expected to be extremely hot, increasing the risk of heatstroke.
The key weather characteristics for July were as follows:
Record-Breaking Temperatures Nationwide
Temperatures were exceptionally high across Japan. Warm air flowed easily into northern Japan, while eastern and western Japan, Okinawa, and Amami were covered by warm air. This resulted in the highest July temperatures since statistics began in 1946 for Okinawa and Amami, and a tie for first place in eastern Japan. At 62 of the 153 meteorological stations nationwide, the monthly average temperature for July reached an all-time high (including 12 ties). The deviation from the standard value of Japan’s monthly average temperature was +2.16°C, making it the highest July temperature since records began in 1898.
Increased Precipitation on the Sea of Japan Side of Northern Japan
Precipitation was significantly higher on the Sea of Japan side of northern Japan due to low pressure, the rainy season fronts, and humid air.
Higher Sunshine Hours in Okinawa and Amami
Sunshine hours were significantly higher in Okinawa and Amami, which were often covered by the Pacific high-pressure system until mid-month.
July Weather Overview
In northern Japan, warm air from the south flowed in easily. Eastern and western Japan, Okinawa, and Amami experienced strong Pacific high pressure, causing warm air to cover these regions. Strong sunlight led to record high temperatures in various areas, resulting in a considerably high monthly average temperature nationwide. The monthly average temperature difference from the normal was +2.3°C in eastern Japan and +1.3°C in Okinawa and Amami, marking the highest July temperature since statistics began in 1946 for these regions. The monthly average temperature at 62 of the 153 meteorological stations nationwide was the highest ever recorded for July (including 12 ties).
The deviation from the standard value of the monthly average temperature in Japan, based on observation values from 15 stations used to monitor long-term climate change, was +2.16°C, surpassing last year’s record and making it the highest July since records began in 1898.
In northern Japan, the Sea of Japan side was affected by low pressure and humid air, as well as the rainy season front that often stagnated in the Tohoku region in the first and second halves of the month. Some areas experienced record-breaking heavy rain, including a linear rain band in Yamagata Prefecture around the 25th. Consequently, monthly precipitation was quite high on the Sea of Japan side of northern Japan. On the Pacific side of northern Japan, there were days covered by a mobile high-pressure system in the first half and middle of the month, resulting in high monthly sunshine hours.
On the Sea of Japan side of eastern Japan, monthly precipitation was high due to the influence of the rainy season front and humid air throughout the month. On the Pacific side of eastern Japan and western Japan, the middle of the month was influenced by the rainy season front and humid air, but the first and last halves of the month were often covered by the Pacific high-pressure system, leading to low monthly precipitation on the Pacific side of eastern Japan and high monthly sunshine hours on the Pacific sides of eastern and western Japan.
In Okinawa and Amami, the area was covered by the Pacific high-pressure system until mid-month, resulting in a significant increase in monthly sunshine hours. However, monthly precipitation was high due to heavy rain and severe weather caused by Typhoon No. 3 in the latter half of the month.
August Forecast: Continued Heat
The Japan Meteorological Agency announced its “1-month forecast” on Thursday, August 1st. The average temperature nationwide is expected to be “higher than normal” toward the end of August, suggesting that this summer will likely be characterized by prolonged record heat.
Wednesday, August 7th, marks the beginning of autumn according to the 24 solar terms, but the record heat is expected to continue from mid- to late August, prolonging the battle against the heat.
