Thời tiết St. Louis theo từng tháng

With neither mountains nor large bodies of water nearby to moderate the climate, St. Louis experiences extremes of temperatures at both ends of the scale. The Winter cold from December through March can be brutal to the unaccustomed body, as can the Summer heat from June through September. The Mississippi River makes this area humid, though temperatures are generally moderate. Storms can occur at any time of the year. July and August are hottest and most humid, and January and February are cold, with occasional snow. Normal temperatures range from 21°F in the winter to 90°F in the summer (-6°C to 32°C), but summer highs of 100°F and winter lows of 0°F are not uncommon (38°C and -18°C). Heat indices in the summer months factoring in humidity average around during the day and at night, but it's not unheard of to have heat indices climb upwards to and not go below on some exceptionally hot and sweltering days.

St. Louis forum threads describe January as a genuine midwestern winter: a season that brings both snow and ice storms, with changes drastic enough that mild days and properly cold ones trade places within the same week. Local opinion splits in a way posters lay out themselves - one longtime resident loves the winters here for the ice and snow, another native flatly says he hates the season and lives for the rest of the year - but even the detractors frame winter as one quarter of a four-season deal, with spring and fall the months everyone names as the payoff. Transplants from milder climates warn that the first winter here is a genuine shock. Our record backs the cold: January averages a high near 5C against lows around -5C, roughly 7cm of snow across the month, and a feels-like that can reach toward -9C once wind gets involved. The takeaway from the threads: come prepared for real winter, and treat a blue-sky cold snap as the good version of the month.

Regulars call April the most beautiful month here for the blossom and new leaves, and immediately qualify it: this is also when storms and rapid weather swings are most likely, chilly evenings alongside daytime warmth, and their standing advice is to check a local forecast a day or two out rather than trust a seasonal average. Our row shows the range that produces - 19.9C over 6.5C, with 109.5mm of rain across 9.1 days and a trace of snow, 0.5cm, still possible early in the month. Spring and autumn are named as this city's best seasons overall, and April earns that with qualifications rather than without them. The record: humidity 64 percent, 9 hours of sun, a 20.6 kph wind and AQI 42.

Ask the Saint Louis forum for the best time of year and the answer keeps coming back the same: May, then later September into early October, from both a weather and an outdoor-events point of view. The reasoning is what follows it - June through early September is described as quite hot and humid, not New Orleans hot but close, and worth avoiding where you have the choice. May gets the festival calendar without the swelter. The trade-off is water: it is one of the wettest months on the calendar here, though it arrives in bursts rather than all-day grey. The record: 25.6C days, 13.2C nights, 9.8 precipitation days carrying 139.1mm between them, humidity near 70 percent, 10 hours of sun and AQI 53.

Regulars describe this month as a genuine toss-up rather than a settled pattern - balmy and pleasant one visit, oppressively humid like the Deep South the next, with the odds of the muggier version rising the closer the calendar gets to July. Our row backs the real heat and building humidity, 31.3C reading as a hot 34C at 66 percent humidity, over 18C nights, with 91.3mm of rain across 6.9 days. Regulars comparing this month to August don't find a clear winner on crowds either, both drawing similar numbers, so the honest deciding factor ends up being which version of the heat gamble a visitor is more willing to take. The record: 12 hours of sun, a 14.7 kph wind and AQI 68.

St. Louis forum threads are blunt that July brings genuinely miserable heat and humidity, with posters comparing it directly to central-to-south Florida conditions - though unlike Florida's near-daily afternoon rain, St. Louis thunderstorms don't necessarily show up every day to break the heat. Day-to-day variation is real: one poster noted it's entirely possible to get an 80F day in the same stretch as a 100F day with a heat index near 115F. The consistent recommendation for anyone finding July too intense: September brings a noticeably more comfortable stretch, with the comfort level improving further as that month progresses.

September is the month St Louis regulars pick alongside May, and their framing is that it improves as it runs: the first week or so can still be properly hot, a hangover from a humid July and August, and the comfort builds week by week, with the last third the part they recommend. Mid-September sits in the low 80s Fahrenheit, though they are careful to add that the odd hot day still jumps up out of nowhere. It is fairly dry by local standards too - our row's 83.1mm falls across only 5.3 days, which is thunderstorm rain rather than drizzle - and that combination is why the outdoor events calendar fills up. The record: 28.9C days that feel like 30C, 14.7C nights, humidity 67 percent and 10.2 hours of sun.

Locals put October among the best weeks here and give a date for the end of it: the turn usually does not happen until around Halloween, so the month is autumn in colour and late summer in temperature. Our row reads 21.7C by day against 7.7C at night, a fourteen-degree fall that catches people who packed for the afternoon, and the felt figures are 20C and 6C in a 17.2 kph wind. Rain is light and infrequent, 70.8mm across 5.6 days, and the 0.1cm in the snow column is the first hint of the season rather than a forecast. Early October also beats the fall road-trip crowds further out. The record: humidity 66 percent, 7.8 hours of sun and AQI 36.