Dunno, Maybe Nintendo are trying a new set of icons and testing them on Japan first, Though the company is Japanese, They should be allowed to give Japan better icons
"There are slight variations of the Forecast Channel in different regions. When viewing weather conditions in Japan, a different set of weather icons is used. The Japanese icons were originally going to be used for all regions, but NOA (Nintendo of America) requested that more life-like icons be used. NOA also requested that the current weather conditions be displayed on the start up screen. Nintendo of Europe made a request that certain icons be made more distinct, such as the storm clouds, so that it would be possible for the user to tell if an area is getting rain, snow, sleet, hail, or thunderstorms. Additionally, the laundry index was only featured in the Japanese version. [7]"