ワシントンD.C.の月別の天気

D.C.'s climate has an undeservedly bad reputation; there is a popular myth that the city was built on a swamp with the purpose of discouraging a large bureaucracy—after all, if no one wanted to live in D.C., then there wouldn't be too many bureaucrats. This is all untrue. In reality, what is now the National Mall had been mudflats, but there was no swamp, and in the early 1800s, most of the city's land was used to grow tobacco, corn, and apples. The city's climate is really just a milder version of that in New York and parts of Northeast with short, cool winters and hot, humid but manageable summers. The weather is generally extremely pleasant during the spring and fall. It's hard to beat spring in D.C. The northerly subtropical climate results in cool breezes, moderate temperatures, lush growth, flowers, budding trees, and, of course, the cherry blossoms. The most beautiful time of spring usually falls from April to mid-May.…

Washington DC forum threads describe January as genuinely the coldest month, with average highs in the low 40s Fahrenheit and lows in the mid-20s, plus real wind chill that makes it feel colder still. A typical winter brings around 6 inches of snow total for the month in smaller spurts rather than one big dump, though posters noted an occasional major coastal storm can bring far more at once - DC still gets meaningfully less snow than cities like Boston given its more southern, coastal-influenced position. The consistent packing advice: several thinner warm layers under a proper coat work better than one very thick jacket, plus wool accessories that handle wet weather better than cotton.

Washington's April threads warn about the swing more than the average: day to day it can run anywhere from about 4°C to 27°C, against a real monthly high near 19°C and lows around 8, and it rains often enough that regulars pack a pocket poncho as standard. Jacket and long trousers rather than shorts, but no hat and gloves needed. The bigger warning is cost and crowds — April is peak season here, and early April stacks the Cherry Blossom Festival, spring break and school groups on top of each other whether or not the blossom actually coincides.

Washington DC-forum threads on late May draw a before/after line at Memorial Day: earlier in the month runs fair and warm with just the odd afternoon thunderstorm, while posters note humidity climbs noticeably by late May and into June, ahead of July and August's muggier stretch. The record backs the thunderstorm read more than the 'dry spring' reputation: 137mm of rain across more than twelve days, the wettest month on this destination's calendar, alongside 24.6C days, 13.4C nights and 9.3 hours of sun. Good jacket-optional weather, but pack for rain more than forum nostalgia about 'before the humidity' suggests.

June here is hot and humid but not yet August, and regulars are precise about the pattern: mid to high eighties by day, sixties at night, and afternoon thunderstorms that come out of nowhere, rain hard for a few minutes and leave the air more humid than before. Our row gives 29.7C reading as 32C over 18.6C nights, with 107.1mm across 9.4 days, which is eleven millimetres a time. Their packing advice follows the humidity - loose natural fibres in light colours, because synthetics turn into plastic bags - and their warning is the opposite problem, that indoor air conditioning is usually set far too cold. The record: humidity 69 percent, 11.4 hours of sun and AQI 68.

Regulars time this city by the school calendar. Labour Day is the first Monday of September and ends the summer season; October brings the school groups back in force; the fortnight between is the quietest good weather of the year. The weather follows the same split - the first week is still summer, mid-80s with the humidity to match, and the drier air does not usually arrive until mid-to-late month. Our row averages 27.8C reading as 30C at 74 percent humidity with a 16.1C dew point, over 17.3C nights, and 108.4mm of rain across 8.1 days. Book the second half if you can. The record: 8.6 hours of sun and AQI 47.

Locals give October a spread rather than a temperature: "temps can be 30–90. Usually 40–70" °F, with "daytime highs in the low 60s around then." That thirty-degree usual range across a single month is the thing to plan for — the first week and the last week can feel like different seasons. Their advice on forecasts is to look four or five days out and no further, because it varies widely. The month's reputation is good enough that one regular describes it as when people from colder places start heading south. Our record puts October at 20.8°C days and 12.1°C nights with 9 rain days — comfortably inside the forum's "usually 40–70" band, and well clear of the humidity that defines a Washington summer.