Nikkō hava durumu: ay ay

Regulars are specific the lower Toshogu area can turn cold and rainy with sleet even as the mountains above stay genuinely hard to predict, snow at higher elevations a real possibility - one memorable year even brought a snowstorm as late as April 1st. Our row backs that cold, genuinely wet read, 10.1C over -0.1C nights feeling as low as -4C, with a substantial 131.9mm of rain across 14.6 days and real snow, 32.4cm. Regulars are consistent Lake Chuzenji specifically runs colder and more exposed than the lower town, staying cold and crisp even late in the month. Thick coats, hats and gloves remain the standard advice throughout rather than an early-spring wardrobe. The record: humidity 73 percent, 8.5 hours of sun and a 13 kph wind.

For once our snow column is not describing a distant hillside: visitors to Nikko in early April report actual snow, very cold air around Kegon Falls, and at least one April storm that made roads impassable, which is what the 8.5cm in our row is. The split to plan around is inside the destination. Downtown Nikko is the mild part at 15.2C over 4.8C; up at Lake Chuzenji, several hundred metres higher, the mountains are still white and the woods still under snow while the town below is in spring. If the Fukiware-to-Chuzenji road closes there is a low route that adds about two hours. And regulars are blunt that this is not a cherry-blossom destination - Nikko is deciduous forest, not sakura. The record: 142.6mm across 14.9 days, 9.1 hours of sun and AQI 55.

Forum posters describe May in Japan generally as warm to lovely, with the rainy season not typically starting until early-to-mid June, though conditions can be changeable - a few sunny days can be followed by a day or two of rain. Posters flag a real elevation effect specific to Nikko, though: up at Lake Chuzenji, considerably higher than Tokyo, conditions can turn freezing and windy even on an otherwise sunny, warm day down in town, sometimes with fog or drizzle even when it's dry and pleasant at lower elevation - all while cherry blossoms can still be blooming up there in May. Posters consistently recommend packing for a wide range, from short sleeves up to a light or down jacket for higher-elevation stops, plus a folding umbrella just in case.

The standing Japanese advice for June is that the tsuyu is bearable - light rain rather than torrential, warm rather than hot days, not raining every day, with the season usually starting around the 10th. Nikko is the place that advice under-describes. Our row carries 217.4mm across 22 precipitation days at 85 percent humidity, two days in three and ten millimetres on each, because this is mountain country rather than Tokyo. What goes first is the view: one June visitor could not see Kegon Falls at all for fog. What is at its best is the planting - the ajisai hydrangeas and the moss are the reason several regulars pick June anyway. Come with indoor options and a flexible order. The record: 22.7C days, 14.9C nights, 8.6 hours of sun and AQI 57.

September here can be too foggy and wet for good visibility, and regulars say October and November both run drier - our row backs that with 241.5mm across 23 days at 87.9 percent humidity, easily this destination's wettest column of the ones we carry. The consolation is Kegon Falls itself: the volume of water is at its best now, and visitors who caught a clear late-September day call the falls robust and colourful with the season's first hints of colour already showing. Peak foliage in the upper park is a month or more away, mid to late October. Our temperature reads gently, 23.8C over 17.6C, with only 7.5 hours of sun a day standing behind that rain total. The record: an 8.4 kph wind and AQI 38.

The colour here is a question of altitude, not date. Regulars are blunt that the town and shrine area is mostly cedar and does not turn at all, so the autumn everyone comes for is up the Irohazaka road at Chuzenji and Kegon, and by late October that upper ground is in full colour. The cost is the same road: weekends are extremely crowded and the bus up to Oku Nikko can hold you for hours, so the advice is a weekday and a very early start. Light layers do it in October at 17.9C over 10.6C. Our row adds what the board leaves out - 197.7mm across 17.4 days and only 7 hours of sun - so this is a wet month to be planning a view in. The record: humidity 84 percent, a 9.2 kph wind and AQI 32.

Nikko's forum is consistent that fall foliage peaks in October and is essentially gone by mid-to-late November, with posters describing colder conditions setting in fast - morning frost is common late in the month, and a bit of snow becomes a real possibility. Visitors who went in the first half of November generally had no complaints, describing mostly clear weather with only occasional rain. For anyone specifically chasing peak color into late November, forum regulars consistently redirected to Hakone or the Fuji Five Lakes area instead, where the display tends to hold on longer.