Sure, here is a summary of the average monthly weather for major cities in Japan:
Tokyo:
- January: 5°C (41°F), partly cloudy
- February: 6°C (43°F), partly cloudy
- March: 9°C (48°F), partly cloudy
- April: 14°C (57°F), partly cloudy
- May: 19°C (66°F), partly cloudy
- June: 22°C (72°F), mostly cloudy
- July: 26°C (79°F), mostly cloudy
- August: 27°C (81°F), mostly cloudy
- September: 24°C (75°F), mostly cloudy
- October: 19°C (66°F), mostly cloudy
- November: 13°C (55°F), partly cloudy
- December: 8°C (46°F), partly cloudy
Osaka:
- January: 6°C (43°F), partly cloudy
- February: 7°C (45°F), partly cloudy
- March: 10°C (50°F), partly cloudy
- April: 15°C (59°F), partly cloudy
- May: 20°C (68°F), partly cloudy
- June: 24°C (75°F), mostly cloudy
- July: 28°C (82°F), mostly cloudy
- August: 29°C (84°F), mostly cloudy
- September: 26°C (79°F), mostly cloudy
- October: 21°C (70°F), mostly cloudy
- November: 15°C (59°F), partly cloudy
- December: 10°C (50°F), partly cloudy
Kyoto:
- January: 5°C (41°F), partly cloudy
- February: 6°C (43°F), partly cloudy
- March: 9°C (48°F), partly cloudy
- April: 14°C (57°F), partly cloudy
- May: 19°C (66°F), partly cloudy
- June: 23°C (73°F), mostly cloudy
- July: 27°C (81°F), mostly cloudy
- August: 28°C (82°F), mostly cloudy
- September: 25°C (77°F), mostly cloudy
- October: 20°C (68°F), mostly cloudy
- November: 14°C (57°F), partly cloudy
- December: 8°C (46°F), partly cloudy
Sapporo:
- January: -4°C (25°F), mostly cloudy
- February: -4°C (25°F), mostly cloudy
- March: 0°C (32°F), mostly cloudy
- April: 6°C (43°F), mostly cloudy
- May: 12°C (54°F), mostly cloudy
- June: 16°C (61°F), mostly cloudy
- July: 20°C (68°F), mostly cloudy
- August: 22°C (72°F), mostly cloudy
- September: 18°C (64°F), mostly cloudy
- October: 11°C (52°F), mostly cloudy
- November: 3°C (37°F), mostly cloudy
- December: -1°C (30°F), mostly cloudy
Fukuoka:
- January: 6°C (43°F), partly cloudy
- February: 7°C (45°F), partly cloudy
- March: 10°C (50°F), partly cloudy
- April: 15°C (59°F), partly cloudy
- May: 20°C (68°F), mostly cloudy
- June: 24°C (75°F), mostly cloudy
- July: 28°C (82°F), mostly cloudy
- August: 29°C (84°F), mostly cloudy
- September: 25°C (77°F), mostly cloudy
- October: 20°C (68°F), mostly cloudy
- November: 14°C (57°F), partly cloudy
- December: 9°C (48°F), partly cloudy
I hope this information is helpful!