Ulaanbaatar (Ulan Bator) — sää kuukausittain

Although summer daytime temperatures are mild and average around 24°C and nights around 13°C, the city shivers in sub-zero temperatures for five months of the year. January and February are the coldest months, with temperatures hovering between -15°C to -30°C at night. As a result of these prolonged periods of intense cold, the city has an average annual temperature of , giving it the dubious distinction of being the world's coldest capital. The cold is dry, however, and there is not much wind chill due to temperature inversion. Heat island effect also means the city center is warmer than the outskirts. Summer can be very hot at times, with several days above 31°C and warmer nights above 17°C, so one should avoid heat stress and use sunscreen when necessary. The sun is up from 05:00 to 20:45 in June, and from 08:30 to 17:00 in the winter. If you have breathing problems, be aware that Ulaanbaatar has high levels of air pollution during the winter.…

Ulaanbaatar forum regulars describe January in genuinely extreme terms: temperatures “can drop to -30°C during the day and -45°C during the night” on the coldest stretches, with average readings still running “-24 to -11°C.” Most of the tourist industry — regulars estimate 80% — closes for the season entirely, with only a handful of camps near the city staying open year-round. What survives: a city tour, skiing at the Sky Resort, and dog-sledding tours, the last one specifically popular. Travel outside Ulaanbaatar gets a hard warning — roads are called treacherous, hellish, genuinely risky rather than merely inconvenient. Our record: -11.2°C days, -24.1°C nights and a feels-like low of -29°C — brutally cold, matching the “extreme cold, most tourism shuts down” read almost exactly.

Ulaanbaatar forum threads describe February as one of the coldest months of the year, with posters citing a range as extreme as -25C to -55C in the harshest conditions, though a more typical winter stretch was described as -20 to -35C. The air was flagged as genuinely arid despite the extreme cold, which posters said makes the chill feel slightly different than a damp cold of the same number. Posters were consistent that the bitter cold doesn't rule out a real visit - a well-prepared multi-layered, fur-lined or fleece-inner jacket plus thick, high-grip boots for icy streets were the standard packing advice, and posters specifically recommended February's ice festivals, including the one held on Khövsgöl Lake, as a genuine highlight of the season rather than something to avoid.

Regulars call spring and early summer the hardest stretch of the year to forecast here - warm enough in the Gobi and not especially cold in the north on a good day, but capable of dropping below freezing with rain or even snow with little warning. Our row shows exactly that volatility rather than a settled month: 17.8C by day but only 14C in the wind, against 1C nights that feel like -3C, with 7.3cm still in the snow column and 24.5mm of rain across 4.9 days. The real season here, regulars are consistent, is June through September; May gets you dust on the steppe and a Lake Khuvsgul still frozen over, which suits a specific kind of trip more than a typical one. The record: humidity 44 percent, 12 hours of sun, a 19.6 kph wind and AQI 46.

June is inside the Mongolian summer, which regulars date from late May to mid-September, and the figures they give for Ulaanbaatar - 20 to 30C by day, chilly once the sun goes - are our row's 23.6C over 8.1C almost exactly. That night figure is the whole packing problem: the day can feel like shirtsleeves and the evening reads as 6C. Out in the Gobi the same gap opens wider still, hot by day and cold at night, and the advice is layers plus something genuinely warm rather than a jacket chosen for the daytime. Several regulars prefer September to June for the desert itself. Our row also carries 0.8cm of June snow, which is the high ground in the grid square rather than the city. The record: 47.7mm across 9.3 days, humidity 53 percent, 12.1 hours of sun and 16 hours of daylight.

July is Naadam month and the forum's favourite time to be in Mongolia, with the caveat that summer here means variability rather than warmth. Averages land near 24°C by day falling to about 12 overnight, but posters describe days pushing past 30°C, swings of 20°C between afternoon and night, and — rarely — snow even in July. It is also the wettest stretch of the year: mostly clear skies, punctuated by a few very heavy downpours. The packing advice is consistent across threads — a wind- and rain-resistant light jacket with thermal or fleece layers underneath. For Naadam itself, tickets go on sale at the Central Stadium about a week ahead and the quota routinely runs short.

August is the wettest month of the Mongolian year and regulars treat that as the price of the scenery: the rain is why the landscape is green through the summer, and the season runs June to the end of September. July is the hot, reliably sunny one, past 30C; August cools, and September cools further with more rain. They put the gap between day and night at about fifteen degrees, with nights near 15C early in the month - our row has 22.5C over 9.1C - and warn that snow can fall late in August or early in September. Our 79.3mm falls across 12.4 days. The record: humidity 69 percent, 10.5 hours of sun, a 14.1 kph wind and AQI 38.

Regulars are specific that a first, brief snowfall typically arrives around mid-month, lasting just a day before conditions warm back up again - a genuine marker of the summer-to-autumn transition rather than the start of real winter. Our row backs that mild-by-day, genuinely cold-by-night read, 17.4C over 2.1C nights feeling -1C, with 42.6mm of rain across 7.6 days and a trace of early snow, 5.1cm. Regulars are consistent early in the month brings comfortable daytime temperatures around 20C with plenty of sun, even as nights already turn genuinely cold enough to need real warm layers. This remains a workable month for the countryside and national parks before deeper winter sets in. The record: humidity 64 percent, 9.7 hours of sun, a 16 kph wind and AQI 36.