ボストンの月別の天気

ボストンを訪れるベストシーズンは5月、6月、9月です — 9月は90/100、最高24°C、雨の日7日。 ベストな季節は夏(6月〜8月)で、平均82/100です。

最も不向きな月は1月で、41/100です — 極寒、雨が多い、空気がきれい。 1月を見る →

2026年9月更新 · ERA5再解析による気候平年値

周辺も含めて旅を計画するなら アメリカ合衆国旅行のベストシーズン →

ボストンBoston, United States🇺🇸 アメリカ合衆国 · 米国北東部・カナダ大西洋岸 · 都市90
  1. 411月
  2. 512月
  3. 593月
  4. 704月
  5. 865月
  6. 896月
  7. 767月
  8. 808月
  9. 909月
  10. 7410月
  11. 6311月
  12. 4612月

ベストな季節:6月〜8月(平均82/100) · 最も不向きなのは1月(41/100)

日中
24°C
15°C
雨の日
7
日照
8.5 h
湿度
76%
日の長さ
13 h
ボストン(アメリカ合衆国)
写真: Phil Evenden · Pexels

ボストンの月ごとのようす

ボストンに最も合う旅のタイプでの100点満点の快適スコア、気候平年値による平均最高気温・雨の日数・1日の日照時間、そして混雑具合の目安です。

スコアランク最高日照混雑イベント
1月41F3°C9日6時間ピーク2
2月51D6°C9日7時間閑散1
3月59D9°C9日8時間混雑1
4月70B14°C10日9時間混雑2
5月86A20°C9日10時間混雑2
6月89A26°C9日11時間混雑1
7月76B29°C8日11時間ピーク3
8月80A29°C8日11時間ピーク2
9月90S24°C7日9時間ピーク2
10月74B18°C9日7時間ピーク3
11月63C11°C8日7時間ピーク1
12月46F6°C9日6時間ピーク3

ボストンの年間イベント

祭り、自然の見どころ、祝日、そして注意したい季節 — 厳選し出典を明記しています。詳しくは各月のページで。

4月
  • Boston Marathon4月14日〜21日(例年)祭り
  • Whales on Stellwagen Bank4月15日〜10月20日(例年)自然
5月
  • Commencement season5月8日〜25日(例年)季節
7月
  • Boston Pops on the Esplanade7月4日祭り
  • Independence Day7月3日〜5日祝日
8月
  • Student move-in weekend8月28日〜9月4日(例年)季節
10月
  • Head of the Charles Regatta10月14日〜22日(例年)祭り
  • Fall colour10月5日〜28日(例年)自然
11月
  • Thanksgiving11月25日〜29日祝日
12月
  • First Night12月31日〜1月1日祭り
  • Nor'easter season12月1日〜3月15日(例年)要注意

ボストンの年間イベントをすべて見る →

9月のボストンの混雑

その場所自体の混み具合 — 学校休暇や大型連休、編集部がタグ付けした月、そして天気の良さによる人気の高さ。快適スコアには含まれません。

ピークの混雑Student move-in weekend、アメリカ合衆国のSummer break(推定)

123456789101112

ピークの混雑混雑ショルダーシーズン閑散

ボストンへ行く前に知っておきたいこと

旅行者自身の旅行記から、実際の体験を原文へのリンク付きで引用しています。

ビザ・入国

A traveler calls the Freedom Trail hands-down the highlight of his Boston visit, walking the full 2.5-mile red-brick route from Boston Common to the Bunker Hill Monument across the Charlestown bridge and hitting all 16 Revolutionary-War-era sites along the way. He describes the specific appeal as the trail letting you experience the city's present-day beauty and its founding history simultaneously, rather than choosing between a walking tour and a history lesson. He notes a practical navigation quirk worth knowing: the trail is marked by a literal line of bricks set into the sidewalk, and on stretches where sidewalks have been repaired or torn up, that brick line can disappear for a block or two, making a phone map or the official app a useful backup rather than relying purely on looking down. Posters generally recommend comfortable walking shoes as the single most important prep, given the full trail easily takes several unbroken hours on foot.
Bucketlistly · 原文を読む ↗

ボストンの旅行者の声

実際に訪れた人たちの声です — 通年のメモを先に、そのあと月ごとに並べています。

Almost any time of the year is a good time to visit Boston. June to September is the height of the tourist season. Every corner of the city takes advantage of the warm weather and is packed with festivals and special events. While it is further north than other US cities, Boston is no stranger to the summer heat and humidity experienced by cities further south. Generally, summer heat indices average around during the day and at night; but from time to time, there are some instances each summer with daytime highs near alongside dewpoints and overnight lows around for a few days. These uncommon instances can cause outdoor activities you do at the height of an exceptionally sweltering summer day to leave you drenched in sweat, as heat indices can climb upwards to or even surpass it, but these sweltering periods generally pass after no more than a few days. There are still regularly summer days where temperatures are more moderate and comfortable with daytime temperatures around .…
Wikivoyage contributors · 通年 · 7日前 · Wikivoyageで続きを読む ↗ (CC BY-SA 4.0)
Boston forum threads describe January as the coldest and snowiest stretch of the year, with typical highs in the 20s-30s Fahrenheit and real potential for a nor'easter or blizzard - winter precipitation here tends to arrive as snow rather than rain given how cold it stays. Posters were candid that snow totals are genuinely unpredictable from year to year: some Januarys bring almost nothing, others dump a couple of feet with little warning. Wind was flagged repeatedly as a real factor too, with Boston's reputation as a notably windy city compounding the cold and damp. Standard advice across threads: waterproof winter boots, real cold-weather layers, and flexible plans given how quickly conditions can change.
MassachusettsRegular · 1月 · 5日前 · Tripadvisorで続きを読む ↗
Locals refuse to give April a number, and they're right to. "April is a huge transition month here and it could be snowing or 85°F." Another puts the range at "the 40s or the 90s, sunny or cloudy or rain, but not usually snow" — the two posters don't even agree on whether snow is on the table, which is itself the answer. The practical advice that follows is unusually specific: "if you come on April 12th, don't pack until you check the weather on April 11th. Really." Layers, a rain jacket, a hood or hat, and warm things underneath. Our record gives April 13.4°C days and 4.7°C nights with 1.9cm of snow still on the books, plus 22.6 kph average wind — but an average is exactly the wrong tool for this month, and the forum knows it.
Tripadvisor community · 4月 · 6日前 · Tripadvisorで続きを読む ↗
May warms faster here than any other month - regulars put the end of it near 72F by day and 55F at night, which is a different city from the one that started the month. Our averages sit in the middle at 20.3C over 10.4C, reading as 19C and 7C in a 19.6 kph wind. It is also among the driest months, 78mm across 9 days, so the waterproof is optional in a way it rarely is here. What is not optional is a layer for the water: the harbour is 13.4C, and whether the day feels like spring or like March depends mostly on which way the wind is coming off it. The record: humidity 73 percent, 9.7 hours of sun inside 14.6 of daylight, and AQI 43.
TheFastestWarmUpOfTheYear · 5月 · 3日前 · Tripadvisorで続きを読む ↗
Regulars will not forecast June here, they give a range: the fifties to the nineties, warm by day with any of hot, humid, rainy or chilly at night. Our row's 26C over 15.7C is the middle of that and not a promise. Their packing list follows from it - plan for the eighties, add a sweater and a waterproof layer, and treat everything as removable. Rain is 79.6mm across 8.8 days. One number worth knowing before booking a boat: the harbour is 16.8C this month, so a morning on the water is a jacket occasion whatever the city is doing, helped along by an 18 kph wind. The record: humidity 73 percent, 11 hours of sun inside 15.2 of daylight, and AQI 51.
FiftiesToNineties · 6月 · 3日前 · Tripadvisorで続きを読む ↗
Regulars describe the first half of the month as often quite hot and humid, though the intensity typically backs off from July's peak - a pattern regulars are candid doesn't always hold, since some summers bring heat waves that persist well into August regardless. Our row backs the warm, humid read, 28.7C reading as a hot 30C at 73 percent humidity, over 19.1C nights, with 85.5mm of rain across 7.7 days. Regulars planning day trips to Cape Cod, Nantucket or Martha's Vineyard treat this month as prime season for exactly that kind of coastal escape from the city heat. The sea sits at 18.7C. The record: 10.7 hours of sun, a 16.7 kph wind and AQI 52.
HeatBacksOffFromJulyMostYears · 8月 · 3日前 · Tripadvisorで続きを読む ↗
Boston-forum threads on September timing point past Labor Day: September 1st is the city's biggest moving day, when students and families flood in, and the holiday weekend right after is one of the busiest of the year. Regulars say the reward for waiting is real - mid-to-late September turns noticeably more relaxed once move-in is done, with thinner crowds and cheaper rooms than either summer or the foliage season that follows. Weather holds up too: early September is still warm enough for the beach, usually less humid than August though posters admit there's no guarantee. The record: 24C days, 15.1C nights, 83mm of rain across 7.3 days, 8.5 hours of sun and a 19.3C sea - good swimming weather if you can dodge the moving trucks.
SeaportSeptemberRegular · 9月 · 4日前 · Tripadvisorで続きを読む ↗
Boston's own foliage runs late, and the forum is consistent about it: early October is too early in the city, peak colour lands at the very end of October into the first days of November, and by around 20 October much of the greater-Boston leaf can already be down if there has been an early freeze or a heavy storm. For colour earlier in the month regulars send you out of the city — west to the Berkshires, or north into New Hampshire and Vermont, all car trips. The weather meanwhile is mild for the latitude: highs near 17°C, cooling to about 10 at night.
Tripadvisor community · 10月 · 6日前 · Tripadvisorで続きを読む ↗

地図のボストンのカードから自分のメモを追加できます。

ボストンのベストシーズンは5月、6月、9月(90/100) — 月別の天気 | SeasonMap