Weather in Osaka

Osaka is in Japan at 34.7°N. The 2001–2020 NASA POWER daily record describes a continental climate with a wide temperature swing. Rain is wet season runs from March to November, inside an annual total of 1753 mm. The wettest month is September at 225 mm; the driest is January at 66 mm.

August is the warmest month (average 26.2°C, high 30.1°C) and January is the coolest (average 3.0°C, low -0.7°C). From the coolest night in January (-0.7°C) to the hottest afternoon in August (30.1°C), the raw range is 30.8°C. On this site the months that score closest to a 22°C day, lighter rain, and moderate humidity are June, July, and September.

Best months to visit Osaka

The three months with the highest comfort score are June, July, and September: June (21.2°C average, 213 mm, 83% humidity); July (25.3°C average, 220 mm, 85% humidity); September (22.6°C average, 225 mm, 84% humidity). They fall in calendar order. The score rewards averages near 22°C, lower rainfall, and humidity near 60%. It is a climate score, not a festival or price calendar.

If you want the wet season itself — fewer crowds, greener landscape, heavier rain — aim at March–November instead of the score.

How warm Osaka gets

The heat peaks in August, when the typical afternoon is 30.1°C. The opposite pole is January, when mornings average -0.7°C.

Mean high across all twelve months is 18.7°C and mean low is 9.9°C. These are 20-year grid averages, so a city station can read a few degrees warmer or cooler.

Rain through the year

The wet season in Osaka starts in March and ends in November (March, April, May, June, July, August, September, October, and November). September is the core of it at 225 mm. January is the other extreme, with 66 mm.

A rainy day here is a day with at least 1 mm in the NASA POWER series. September averages 16 such days; January averages 8.

The calendar in Osaka

January is the coolest month, with lows around -0.7°C and highs near 6.8°C. Rainfall is 66 mm. March is when the wet season typically starts in Osaka: highs near 12.1°C, and rainfall jumps to 116 mm (11 rainy days). April: 17.5°C high, 6.8°C low, 135 mm rain, 78% humidity. In May, Osaka averages 22.3°C by day and 11.9°C at night, with 159 mm of rain. June brings 213 mm and 15 rainy days; temperatures run from 16.9°C to 25.6°C. July stands apart from the months beside it: 29.0°C / 21.6°C and 220 mm.

Peak heat arrives in August: 30.1°C by day, 22.2°C at night, and 84% humidity. September is the wettest month — 225 mm and 16 rainy days, with 84% humidity. In October, Osaka averages 21.0°C by day and 12.3°C at night, with 192 mm of rain. By November the wet season is ending. Osaka still sees about 93 mm, but the next month is usually leaner. December stands apart from the months beside it: 9.4°C / 1.3°C and 76 mm.

How Osaka compares inside Japan

Kobe is about 29 km away: Osaka is 1.2°C cooler than Kobe in its hottest month and 227 mm wetter over the year than Kobe. Kobe’s wettest month is July (204 mm) versus September here.

Kyoto is about 43 km away: Osaka is about as warm as Kyoto at the hot peak and 96 mm wetter over the year than Kyoto. Kyoto’s wettest month is July (210 mm) versus September here.

Nagoya is about 139 km away: Osaka is 1.1°C cooler than Nagoya in its hottest month and a similar annual rainfall (1741 mm in Nagoya). Nagoya’s wettest month is July (225 mm) versus September here.