ロンドンの月別の天気

Despite having perhaps a fair reputation for being unsettled, London enjoys a mild climate on average. As much as one in three days on average will bring rain, though sometimes for only a short period. In some years, 2012 and 2018 being examples, there was no rain for a number of weeks. The fact that Londoners would find this remarkable should be an indication to visitors from drier climates of what they may be in for! Extreme weather is rare. Occasionally there may be heavy rain that can bring localised flooding or strong winds that may down trees and damage roofs, but overall you are unlikely to encounter anything too lively. ===== Winter ===== Winter in London is mild compared to nearby continental European cities due to both the presence of the Gulf Stream and the urban heat effect. The average daily maximum temperature is in December and January.…

London regulars are unanimous that January is “cold and, at times, wet” rather than dramatic — expect “0°C and 10°C,” “damp, grey weather rather than freezing cold,” and snow that “never falls properly... when it does, it's over within hours.” The advice is layering over a full parka: warm coat, hat, scarf, gloves, with snow boots only needed if a forecast actually predicts sub-zero days. The upside forum posters keep repeating: attractions stay open, queues vanish, and hotel prices drop. Our record matches the “cold, not brutal” read: 7.4°C days, 1.7°C nights, 10.6 rain days and just 1.7cm of snow for the month.

Asked what to pack for late May, regulars give the only honest English answer: wet, dry, chilly, warm and sunny are all possible, so the list is layers, a light waterproof and shoes that will take five or six miles a day on uneven ground. Our row lands mild rather than warm - 18.9C reading as 17C in an 18.3 kph wind, over 9.8C nights - with 53.4mm of rain across 10 days, which is a shower every third day rather than a wet month. What May really offers is length: 15.6 hours of daylight with 10.5 of sun. The gardens are the reason people come now, and the last week of the month is also the dearest. The record: humidity 74 percent, a dew point of 7.8C and AQI 46.

Ask what June is like and Londoners on the forum answer with a range, not a number: "the June temperature in London could be anything from 20°C to 40°C," and "the weather in the UK has become even more unpredictable than usual." A more grounded regular puts typical daytime highs in the 70s Fahrenheit — maybe high 60s, maybe 80s on a hot day. The useful consensus is that June is one of the drier months and "an umbrella or a full waterproof jacket is unlikely to be needed," though it can equally be very dry or thundery. Standing advice is layers plus a light raincoat, which covers both. The unarguable part is daylight: this is the longest-light month of the year, and evenings run late. Our record has 20.7°C highs and 16.5 hours of daylight.

I was in London in July and found many trains had spare capcity on the underground system. Be careful of drawing conclusions in European cities in August when many locals disappear off on vacation.

London-forum threads on August are candid that it's the year's peak for crowds - school holidays fill the museums and attractions with families - though several posters note the weather itself runs milder than June or July, without June's harder sun. The catch more than one mentions: much of the city, from shops to older hotels, still doesn't have air conditioning, so a warm spell is felt more than the numbers alone suggest. August's record: 23.7C days, 14.8C nights, 53mm of rain across nine and a half days, 9.7 hours of sun and a clean AQI of 41 - comfortable weather, uncomfortable queues.

Regulars are candid that recent early-September stretches have run warm and sunny, but are careful to add that's no guarantee for any given year - the month can just as easily turn wet, windy and chilly. Our row backs the moderate average sitting between those extremes, 20.7C over 12.3C nights, with 56.2mm of rain across 10.6 days. Regulars picked this month specifically expecting lighter crowds than July or August alongside reasonably decent weather, and are consistent that layering plus an umbrella and cardigan for cooler evenings is the standard advice regardless of how the daytime weather turns out. The record: humidity 78 percent, 7.8 hours of sun, a 19 kph wind and AQI 46.

London's December threads settle on an average around 6°C, a high chance of rain, and darkness closing in by about 4pm. Regulars rate it milder than January or February, and they're clear about timing: the Christmas feel is best from roughly 1 to 21 December. After that it turns awkward — no public transport on the 25th, shops shut, many attractions closed, and Christmas Day meals priced accordingly.