A quick look at the extreme rainfall in Japan

In early July 2018, southwestern Japan experienced extreme rainfall, with some interior stations recording more than twice the usual amount for the wettest day of the year, leading to local return times exceeding 200 years. Observational data from 94 stations show a higher prevalence of positive trends in extreme rainfall probability than negative trends, suggesting a systematic influence beyond natural variability. While a single high-resolution model (EC-Earth T799) qualitatively reproduces these positive trends from 1850 to 2098, the authors state that a lack of sufficient climate models and manpower prevents a robust quantitative attribution statement. The analysis concludes that climate change likely increased the probability of such extreme rains, though the exact magnitude remains undetermined.

• Extreme rainfall in early July 2018 in southwestern Japan was exceptional, with some interior stations measuring more than double the typical amount for the wettest day of the year, resulting in local return times of over 200 years at five specific stations: Urmi, Hiroshima, Okayama, Fukuyama, and Matsuyama.
• Analysis of 94 stations indicates that positive trends in the probability of extreme rainfall are more frequent than negative trends; specifically, 22% of stations showed positive trends at p<0.1, while only 6% showed negative trends at the same level, suggesting that about half of the positive trends are due to systematic factors like climate change rather than natural variability.
• The EC-Earth T799 model, which has a resolution of approximately 30 km, qualitatively reproduces the spatial and seasonal features of rainfall extremes and shows positive trends in the wettest day of the year for southwestern Japan across both the 1850-2006 and 1850-2098 periods.
• The authors conclude that climate change increased the probability of the observed extreme rains, but they cannot provide a quantitative assessment due to a lack of manpower and a shortage of suitable high-resolution climate models.

APA

World Weather Attribution (2018). A quick look at the extreme rainfall in Japan. https://www.worldweatherattribution.org/a-quick-look-at-the-extreme-rainfall-in-japan/

Chicago

World Weather Attribution. A quick look at the extreme rainfall in Japan. 2018. https://www.worldweatherattribution.org/a-quick-look-at-the-extreme-rainfall-in-japan/.

Wikipedia

{{cite report |author=World Weather Attribution |title=A quick look at the extreme rainfall in Japan |date=17 July 2018 |url=https://www.worldweatherattribution.org/a-quick-look-at-the-extreme-rainfall-in-japan/ |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{worldweatherattribution2018quick, author = {{World Weather Attribution}}, title = {{A quick look at the extreme rainfall in Japan}}, institution = {World Weather Attribution}, year = {2018}, month = jul, url = {https://www.worldweatherattribution.org/a-quick-look-at-the-extreme-rainfall-in-japan/}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }