Sign In Become a Member
Donate
Weather Summary Archives

August 2025 Summary – Sunniest on Record

September 5, 2025

  Blue Hill Observatory August 2025 Summary:  August 2025 was cooler and drier than average with much above average sunshine. The approximated…

Agreement required — click “Accept & Continue” below to review and accept the Data Use & Privacy Policy

Access to this content requires acceptance of our Data Use & Privacy Policy.

Enhanced GOES-East visible imagery of Hurricane Erin passing the U.S. East coast on the afternoon of 21 August 2025. The color enhancement emphasizes the cloud phase and distinguishes ice clouds (yellow-orange), liquid clouds (light blue-green), land areas (deep blue), and ocean (black). Imagery courtesy of the College of DuPage (weather.cod.edu).

 

Blue Hill Observatory August 2025 Summary: 

August 2025 was cooler and drier than average with much above average sunshine. The approximated 24-hour mean temperature for the month of 68.5 deg F was 0.2 degrees warmer than the 1891-2020 130-year average for August, and it was 1.8 degrees cooler than the 1991-2020 30-year average. The average maximum temperature of 79.5 deg F was 0.7 degrees cooler than the 30-year normal, and the average minimum temperature of 59.3 deg F was 3.3 degrees cooler than the 30-year normal, which was the coolest average minimum temperature in August since 1987. The warmest period of the month was the second week, which included five consecutive days with a high temperature of 88F or higher. The highest temperature for the month was 94F on the 11th, and the lowest temperature was 51F on the 20th during a cool period of onshore winds prior to the passage of Hurricane Erin far offshore on the 21st. August mean water vapor pressure, which is an absolute measure of water vapor in the air, was 16.8 mb, which corresponded to a mean dew point of about 59F. This amount was below the long-term mean water vapor pressure for August of 18.2 mb, which equals a mean dew point of about 61F, and it was the lowest for the month since 1987. The total precipitation was 1.88 inches, which was 2.03 inches less than the 30-year normal. The greatest amount in 24 hours was 0.68 inches, which occurred during a gusty thunderstorm on the 14th. There were two thunderstorm days during the month, which was two fewer than average, and the total for the year through August increased to 18, which is close to average. The highest sea-level pressure during August was 30.52 inches on the 6th, which tied as the third highest on record for the month. The lowest sea-level pressure was 29.77 inches on the 25th, which was also relatively high for August. The mean wind speed was 9.5 mph, which tied as the second lowest on record for the month, and the prevailing wind direction was from the south-southwest. The highest wind gust was 41 mph from the northeast on the 17th. Hurricane Erin passed far out over the ocean and brought a wind gust to 36 mph from the east-northeast on the 21st. August sunshine was well above average with 305.1 hours of bright sunshine, or 74 percent of possible, which was fifteen percent more than the long-term average for the month. August ranked as the sunniest on record at Blue Hill.

BHO Highest August Sea-Level Pressure, inches (1885-2025):

1) 30.60 on 31 August 2002
2) 30.55 on 25 August 1991
3) 30.52 on 22 August 1957
   30.52 on 6 August 2025
5) 30.49 on 24 August 1967
6) 30.48 on 23 August 1954
7) 30.47 on 19 August 1918
8) 30.45 on 17 August 1942

BHO Lowest August Mean Wind Speed, mph (1885-2025):

1) 9.2 in 2024
2) 9.5 in 1996
   9.5 in 2008
   9.5 in 2021
   9.5 in 2025
6) 9.8 in 2019
7) 10.0 in 1899
   10.0 in 2009
   10.0 in 2022

BHO Highest August Bright Sunshine, hours (1886-2025):

1) 305.1 in 2025 [74%]   
2) 303.7 in 1971 [74%]   
3) 303.2 in 2015 [73%]   
4) 303.0 in 1969 [73%]   
5) 298.1 in 1932 [72%]   
6) 296.7 in 1970 [72%]   
7) 296.6 in 1995 [72%]   

Mike Iacono
Chief Scientist
Blue Hill Observatory

facebookShare on Facebook
TwitterPost on X
FollowFollow us
PinterestSave
←
→
Blue Hill Observatory & Science Center · Legal

Data Use & Privacy Policy

Please read the full Policy before accessing Observatory data · Effective January 1, 2025

Notice: By accessing, downloading, or using any Blue Hill Observatory data or services, you unconditionally accept and agree to be bound by this Policy in its entirety. If you do not agree, you may not access or use Observatory data.
Effective January 1, 2025 · Milton, Massachusetts · bluehill.org
Part I — Data Use Policy
§ 01

Ownership and Proprietary Rights

All observational records, compiled datasets, metadata, database structures, and related materials provided by the Blue Hill Observatory & Science Center are the exclusive property of the Blue Hill Observatory & Science Center. The Observatory has maintained continuous weather observations at the summit of Great Blue Hill since 1885, and the entirety of that record — its compilation, structure, curation, and organization — constitutes a proprietary database protected under applicable United States law, including copyright law and common law database protections.

All rights not expressly granted in this Policy are reserved by the Observatory. No access to or use of Observatory data shall be construed as a waiver of any rights or as a license to use data beyond the scope expressly stated herein.

§ 02

Governing Law and Jurisdiction

This Policy shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts, without regard to its conflict of law provisions. For interactions with international users, this Policy shall apply to the maximum extent permitted by applicable local law.

Any dispute arising from or related to this Policy shall be subject to the exclusive jurisdiction of the state and federal courts located in Norfolk County, Massachusetts. By accessing Observatory data, all users consent to personal jurisdiction in Massachusetts and waive any objection to the venue or inconvenience of such forum.

§ 03

Permitted Uses

Observatory data are made available for the following limited, non-commercial purposes only:

  • Personal study and analysis
  • Educational classroom use
  • Student projects
  • Non-commercial academic research
  • Publication of analyses, figures, models, or conclusions derived from the data, subject to the attribution requirements of Section 4

All other uses require prior written authorization from the Observatory.

§ 04

Attribution Requirement

Any use of Observatory data in any published, presented, or publicly distributed work must include the following verbatim acknowledgment:

“Data provided by the Blue Hill Observatory & Science Center, Milton, Massachusetts. Continuous weather observations since 1885.”

Failure to include proper attribution is a material violation of this Policy.

§ 05

Prohibited Uses

Unless explicitly authorized in writing, Users may not:

  • Resell, license, sublicense, or commercially exploit Observatory data in any form
  • Redistribute the dataset in whole or in part to any third party
  • Publish the dataset for download by third parties
  • Host, mirror, or archive the dataset on any external website, repository, or storage service
  • Upload the dataset to any public or institutional data repository
  • Provide the data through APIs, automated services, or subscription platforms
  • Incorporate the data into any commercial product, software, application, or service
  • Use the data for AI or machine learning systems intended for commercial use or external distribution
  • Use the data to create derivative datasets that enable reconstruction of the underlying observations
§ 06

Commercial Licensing

Organizations seeking to use Observatory data for commercial purposes must obtain a license prior to any such use. Licensing inquiries: data@bluehill.org.

§ 07

Automated Access

Automated scraping, bulk harvesting, or systematic downloading of Observatory data is strictly prohibited without prior written authorization.

§ 08

Enforcement and Remedies

Violation of this Policy may result in immediate revocation of data access, pursuit of legal remedies available under United States law, and referral to applicable authorities. The Observatory reserves all rights to seek injunctive relief, damages, and attorneys’ fees in connection with any unauthorized use of its data.

Part II — Privacy Policy
§ 09–10

Scope & Information Collected

This section governs the collection, use, storage, and disclosure of personal information from visitors to the Blue Hill Observatory website and users of its data services. The Observatory may collect contact information (name, email, organization) when voluntarily submitted, usage data including IP addresses and pages visited, and data download records.

§ 11–12

How We Use Information & Retention

Information is used solely for: responding to inquiries and licensing requests; monitoring and enforcing compliance with this Policy; improving website performance; and communicating Observatory news to opted-in users. The Observatory does not sell, rent, or share personal information with third parties for marketing purposes. Data access records may be retained indefinitely for compliance and enforcement purposes.

§ 13

International Users and Data Transfers

The Observatory is located in the United States. International users acknowledge their information will be processed in the United States under U.S. law. Users requiring specific data processing agreements under non-US law must contact data@bluehill.org before accessing data.

§ 14–16

Cookies, Security & Children’s Privacy

The Observatory website may use cookies for analytics and functionality. By continuing to use the site, users consent to cookie use. The Observatory implements reasonable measures to protect personal information but cannot guarantee absolute security. Observatory data services are not directed at children under 13.

Part III — General Provisions
§ 17–20

Modifications, Severability, Entire Agreement & Contact

The Observatory reserves the right to modify this Policy at any time. Updated versions will be posted at bluehill.org. Continued use of Observatory data following any modification constitutes acceptance of the revised Policy. This Policy constitutes the entire agreement between the User and the Observatory. Questions and licensing inquiries: Blue Hill Observatory & Science Center, Milton, Massachusetts — data@bluehill.org

By accessing, downloading, or using any Blue Hill Observatory data or services, you acknowledge that you have read, understood, and agree to be bound by this Policy.
Effective January 1, 2025 · Blue Hill Observatory & Science Center · Milton, Massachusetts
↓ Scroll to read the full Policy — the agreement checkbox will unlock at the bottom
Main Menu