Boston weather in August: Boston, Massachusetts: normal highs, lows, rain and records for August
Boston in August has a normal high of 80°F and a normal low of 65°F, a daily mean of 73°F, falling from 82°F on the 1st to 78°F by the 31st. Measurable precipitation falls on 9 days in a normal August, 3.23 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 27°C and low of 18°C, 82 mm of precipitation in August.
- NOAA stationBoston Logan International Airport
- Station IDUSW00014739
- Location42.36°N 71.01°W
- Elevation12 ft (4 m)
- From the center2 miles
- Population673,458
- Jan 37° 23°
- Feb 39° 25°
- Mar 46° 31°
- Apr 56° 41°
- May 67° 50°
- Jun 76° 60°
- Jul 82° 66°
- Aug 80° 65°
- Sep 73° 58°
- Oct 62° 48°
- Nov 52° 38°
- Dec 42° 29°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Boston in August?
The normal high is 80°F and the normal low 65°F, for a daily mean of 72.7°F. August is 1.4°F cooler than July and 7.1°F warmer than September. August is the 2nd warmest month of the year in Boston and the 11th wettest. Across the month the normal high falls 4°F, from 82°F on August 1 to 78°F on August 31. From one year to the next August's mean temperature typically moves about 1.7°F either way (NOAA's standard deviation), so roughly two Augusts in three average between 71°F and 74°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 31%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| August 1 | 82°F | 66°F | 31% | 19% |
| August 8 | 81°F | 66°F | 31% | 19% |
| August 15 | 81°F | 65°F | 30% | 18% |
| August 22 | 80°F | 65°F | 29% | 18% |
| August 31 | 78°F | 63°F | 28% | 18% |
Every day of August: normal high, low and chance of precipitation (warmest afternoon August 1, coldest night August 31)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| August 1 | 82°F | 66°F | 31% | 19% | 14 h 30 min |
| August 2 | 82°F | 66°F | 31% | 19% | 14 h 30 min |
| August 3 | 82°F | 66°F | 31% | 19% | 14 h 30 min |
| August 4 | 82°F | 66°F | 31% | 19% | 14 h 20 min |
| August 5 | 82°F | 66°F | 31% | 19% | 14 h 20 min |
| August 6 | 82°F | 66°F | 31% | 19% | 14 h 20 min |
| August 7 | 82°F | 66°F | 31% | 19% | 14 h 20 min |
| August 8 | 81°F | 66°F | 31% | 19% | 14 h 10 min |
| August 9 | 81°F | 66°F | 31% | 19% | 14 h 10 min |
| August 10 | 81°F | 66°F | 30% | 19% | 14 h 10 min |
| August 11 | 81°F | 66°F | 30% | 19% | 14 h 10 min |
| August 12 | 81°F | 66°F | 30% | 19% | 14 h |
| August 13 | 81°F | 66°F | 30% | 19% | 14 h |
| August 14 | 81°F | 66°F | 30% | 19% | 14 h |
| August 15 | 81°F | 65°F | 30% | 18% | 14 h |
| August 16 | 81°F | 65°F | 30% | 18% | 13 h 50 min |
| August 17 | 81°F | 65°F | 30% | 18% | 13 h 50 min |
| August 18 | 80°F | 65°F | 30% | 18% | 13 h 50 min |
| August 19 | 80°F | 65°F | 29% | 18% | 13 h 50 min |
| August 20 | 80°F | 65°F | 29% | 18% | 13 h 40 min |
| August 21 | 80°F | 65°F | 29% | 18% | 13 h 40 min |
| August 22 | 80°F | 65°F | 29% | 18% | 13 h 40 min |
| August 23 | 80°F | 64°F | 29% | 18% | 13 h 40 min |
| August 24 | 79°F | 64°F | 28% | 18% | 13 h 30 min |
| August 25 | 79°F | 64°F | 28% | 18% | 13 h 30 min |
| August 26 | 79°F | 64°F | 28% | 17% | 13 h 30 min |
| August 27 | 79°F | 64°F | 28% | 17% | 13 h 30 min |
| August 28 | 79°F | 64°F | 28% | 17% | 13 h 20 min |
| August 29 | 79°F | 63°F | 28% | 18% | 13 h 20 min |
| August 30 | 78°F | 63°F | 28% | 18% | 13 h 20 min |
| August 31 | 78°F | 63°F | 28% | 18% | 13 h 20 min |
- Normal high
- 80°FAugust average
- Normal low
- 65°FAugust average
- Precipitation
- 3.23 inmonth total
- Days with precipitation
- 90.01 inch or more
- Days at 90°F or more
- 4
- Daylight
- 14 h 30 min to 13 h 20 minAugust 1 to August 31
- Days at 70°F or more
- 29
- Days at 80°F or more
- 18
- Sunshine
- 78%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00014739; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Boston in August?
On a given August day the chance of 0.01 inch or more is 30% on average, highest around August 1 (31%). In all, 3.23 in falls on 9 days of a normal August, 1 of them with an inch or more.
In a normal August in Boston, 4 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00014739.
How humid and windy is Boston in August?
At 3 p.m. the normal temperature is 75°F with 56% relative humidity and a dew point of 59°F; at 6 a.m. it is 65°F with 79% humidity. The wind averages 10.0 mph, most often from the southeast in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 65°F | 58°F | 79% | 8.5 mph | 44% |
| 9 a.m. | 72°F | 59°F | 64% | 9.8 mph | 39% |
| noon | 75°F | 59°F | 56% | 12.1 mph | 34% |
| 3 p.m. | 75°F | 59°F | 56% | 12.4 mph | 30% |
| 6 p.m. | 72°F | 59°F | 64% | 10.7 mph | 34% |
| 9 p.m. | 69°F | 60°F | 72% | 9.1 mph | 51% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00014739. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for August in Boston?
The warmest August temperature on Boston's official record (since 1872) is 102°F, on August 2, 1975; the coldest is 46°F, on August 25, 1940. The wettest August brought 17.09 in (1955).
The August mean against the 1991-2020 normal of 72.7°F: 2021 76.8°F (+4.1), 2022 76.7°F (+4.0), 2023 71.8°F (−0.9), 2024 72.0°F (−0.7), 2025 70.7°F (−2.0), 2026 75.2°F (+2.5). 3 of 6 ran warmer than normal.
| August | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 76.8°F | +4.1°F | 7.00 in |
| 2022 | 76.7°F | +4.0°F | 1.47 in |
| 2023 | 71.8°F | −0.9°F | 6.46 in |
| 2024 | 72.0°F | −0.7°F | 3.70 in |
| 2025 | 70.7°F | −2.0°F | 0.83 in |
| 2026 | 75.2°F | +2.5°F | 0.98 in |
Source: records: ACIS, NWS threaded record BOSthr; recent months: ACIS, station USW00014739. Records and recent months use complete months only.
How does August in Boston compare across Massachusetts?
Across the 35 places PlainClimate covers in Massachusetts, August normal highs run from 76°F in East Sandwich to 85°F in Maynard; Boston's is 80°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.