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Monday, September 15, 2025

September 15, 2025

BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA MONDAY, SEPTEMBER 15, 2025 ALL TIMES ARE…

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BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA MONDAY, SEPTEMBER 15, 2025 ALL TIMES ARE IN EASTERN STANDARD TIME (EST) SUNRISE: 0524E SUNSET:  1753E A MIX OF SUN AND CLOUDS WITH AN ONSHORE BREEZE AND COOLER TEMPERATURES…. We started off with sunshine mixed with some high thin cirrus clouds early this morning, but as the onshore flow freshened, a stratus layer pushed down the coast and has spread over the area. Thanks to the sun and somewhat drier air over the land, the clouds did break up, so it’s created an interplay of sun and clouds into early this afternoon of both stratucumulus and cumulus. Temperatures are cooler today thanks to the wind off the ocean. Readings have reached the low 70s by early this afternoon. Dew point values were a bit lower earlier this morning making for a drier feel to the air than yesterday, but the dew point has since risen back into the low 60s by late this morning into early this afternoon. As such, there is a more humid feel out there this afternoon. Winds were quite light during the wee hours of the morning, but freshened out of the north, then northeasterly by the 7am observation. However, it has veered more easterly by early this afternoon. The speed has been fairly steady since this morning, averaging at around 8mph. The peak gust so far for the day is 20mph, which occurred just after 6:15am this morning. Visibility has been limited today from haziness thanks to the high humidity levels. The view decreased from around 35 miles early this morning to only 20-25mph late this morning as the stratus layer was moving in. It has rebounded back to around 35 miles early this afternoon. The maximum temperature so far today is 71F degrees, which is 2 degrees below the normal high of 73F. The minimum temperature since midnight is 57F degrees, which is 1 degree above the normal low of 56F. ————————————————————– Today’s Observations: 7 A.M. Weather: Thin broken cirrus, stratus layer distant NNW-NNE Temperature: 60F; Dew Point: 57F; Relative Humidity: 89% Wind: NNE @ 8G14 kts Sea-level pressure: 1024.6 mb; 30.26 in. Hg: rising, then more rapidly Visibility: 35 miles, hazy 6-hr Max temp: 63F 6-hr Min temp: 57F 24-hr Precip: 0.00 inches BHO SA 1155 E250 -BKN 35 246/60/57/0308G14/026/ ST LYR DSNT NNW-NNE HAZY/ 8/601 53013 10063 20057 10 A.M. Weather: Broken stratocumulus, thin broken cirrus Temperature: 68F; Dew Point: 61F; Relative Humidity: 78% Wind: ENE @ 8 kts Sea-level pressure: 1026.4 mb; 30.31 in. Hg: rising, then more rapidly Visibility: 25 miles, hazy 3-hr Precip: 0.00 inches BHO SA 1455 E10 BKN 250 -BKN 25 264/68/61/0708/031/ HAZY/ 8/501 53018 1 P.M. Weather: Scattered stratocumulus, scattered cumulus, thin scattered cirrus Temperature: 71F Dew Point: 62F; Relative Humidity: 72% Wind: E @ 7 kts Sea-level pressure: 1026.3 mb; 30.31 in. Hg: rising, then falling Visibility: 35 miles, hazy 6-hr Max temp: 71F 6-hr Min temp: 60F 6-hr Precip: 0.00 inches BHO SA 1755 20 SCT 25 SCT 250 -SCT 35 263/71/62/0807/031/ HAZY/ 8/801 58001 10071 20060 ————————————————————– SUMMARY FOR SUNDAY, SEPTEMBER 14, 2025 TEMPERATURE (DEGREES F) MAX…….79   NORMAL…..74 MIN…….57   NORMAL…..56 MEAN……68   NORMAL…..65 DEPARTURE FROM 30-YEAR (1991-2020) NORMAL…………….+3 TOTAL DEPARTURE FOR THE MONTH………………………-20 [-1.6 DEGREES/DAY] HEATING DEGREE DAYS (SEASON: JUL 2025 THRU JUN 2026) TOTAL HEATING UNITS FOR YESTERDAY……………..0  DEPARTURE……..-3 TOTAL HEATING UNITS FOR THE MONTH…………….22  DEPARTURE……..-1 TOTAL HEATING UNITS FOR THE SEASON……………42  DEPARTURE……..+1 TOTAL HEATING UNITS LAST SEASON TO DATE……….21  DEPARTURE…….+21 COOLING DEGREE DAYS (SEASON JAN 2025 THRU DEC 2025) TOTAL COOLING UNITS FOR YESTERDAY……………..3  DEPARTURE………0 TOTAL COOLING UNITS FOR THE MONTH…………….31  DEPARTURE…….-20 TOTAL COOLING UNITS FOR THE SEASON…………..703  DEPARTURE…….+56 TOTAL COOLING UNITS LAST SEASON TO DATE………737  DEPARTURE…….-34 PEAK WIND GUST (MPH): Note: Instruments designated #1 = Main Tower, #2 = South Tower, F420C, Contacting, Merlin, and Richards are all on Main Tower. E=Estimated F420C (Official)………..15 NE   @   01:22 P.M. VECTOR #1 (1-Sec)……….15 SW   @   12:38 A.M. VECTOR #2 (1-Sec)……….15 SW   @   01:32 A.M. DAVIS #1……………….15 SSW  @   12:34 A.M. DAVIS #2 ………………15 WSW  @   12:39 A.M. RMY #1 (Instantaneous)…..15 SW   @   12:36 A.M. RMY #2 (Instantaneous)…..16 SW   @   01:32 A.M. MERLIN………………….M RICHARDS (C5C) (Inst)……16 SW   @   12:38 A.M. FASTEST MILE: CONTACTING ANEMOMETER/OFFICIAL………………12 SW   @   01:18 A.M. MAXIMUM 2-MINUTE VECTOR #1 AVERAGE…………..12 SW   @   12:39 A.M. MAXIMUM 2-MINUTE VECTOR #2 AVERAGE…………..12 SW   @   12:37 A.M. MAXIMUM 2-MINUTE DAVIS #1 AVERAGE……………12 SW   @   12:47 A.M. MAXIMUM 2-MINUTE DAVIS #2 AVERAGE……………12 SW   @   01:33 A.M. MAXIMUM 2-MINUTE RMY #1 AVERAGE……………..12 SW   @   01:33 A.M. MAXIMUM 2-MINUTE RMY #2 AVERAGE……………..12 SW   @   12:37 A.M. MAXIMUM 2-MINUTE RICHARDS (C5C) AVERAGE………12 WSW  @   01:50 A.M. AVERAGE WIND SPEED AND DIRECTION: CONTACTING/OFFICIAL………6.0 NW [143 total miles] VECTOR #1……………….6.7 VECTOR #2……………….6.8 DAVIS #1………………..6.4 SW DAVIS #2………………..6.1 WSW RMY #1………………….6.5 WSW RMY #2………………….6.8 WSW RICHARDS (C5C)…………..7.0 PRECIPITATION (INCHES) THROUGH THIS MORNING (EST): TOTAL PRECIPITATION 24 HRS ENDING 7 A.M……..0.00 DEPARTURE…..-0.13 TOTAL PRECIPITATION FOR THE MONTH…………..2.14 DEPARTURE…..+0.44 TOTAL PRECIPITATION FOR THE YEAR (2025)…….33.47 DEPARTURE…..-2.84 ————————————————————– PRELIMINARY CLIMATE SUMMARY FOR SEPTEMBER CALENDAR DAY DATA DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN)/SUN(%)/PEAK GUST/VEC1/RMY GUST PEAK GUST: F420C (Official) VEC1: Vector #1 1-second gust RMY:  R.M. Young #1 wind gust recording system (Instantaneous) TSTM: Thunderstorm day (thunder heard some time during day) ….: Data not yet available, records not finalized M:    Missing data 9/1   73/55/64/-5/0.00/221/28            23 NE  VEC1 23 ENE RMY 23 9/2   77/58/68/-1/0.00/714/91            18 ESE VEC1 19 ESE RMY 18 9/3   78/57/68/0/0.00/719/92             21 SSW VEC1 21 SSW RMY 21 9/4   81/56/69/+1/0.00/694/89            26 SSW VEC1 27 SSW RMY 28 9/5   82/63/73/+5/0.12/404/52            30 SSW VEC1 31 SSW RMY 33 9/6   84/64/74/+6/1.05/457/59            55 W   VEC1 55 W   RMY 57 TSTM 9/7   64/56/60/-7/0.97/000/00            16 WNW VEC1 16 NNE RMY 15 9/8   68/49/59/-8/0.00/508/66            21 NW  VEC1 21 NW  RMY 24 9/9   70/53/62/-5/0.00/697/91            22 ENE VEC1 23 E   RMY 23 9/10  65/54/60/-6/0.00/183/24            24 NE  VEC1 25 NE  RMY 25 9/11  77/51/64/-2/0.00/714/94            21 N   VEC1 17 N   RMY 18 9/12  71/56/64/-2/0.00/735/97            24 ENE VEC1 24 NNE RMY 23 9/13  76/55/66/+1/T/634/84               26 S   VEC1 26 S   RMY 25 9/14  79/57/68/+3/0.00/…/..            15 NE  VEC1 15 SW  RMY 15 9/15 The low since midnight is 57F, the daily normal low is 56F. ————————————————————– SEPTEMBER DAILY RECORDS TO DATE NONE. ————————————————————– DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated) RECORDS FOR SEPTEMBER 15 HIGH 89F IN 1931 LOW 35F IN 1913 PRECIP 3.93 INCHES IN 1904 (Extra-tropical storm making landfall in New England on 9/15/1904 passing east of BHO and bringing a storm total of 4.11 inches 9/14-15/1904) PEAK GUST 65e MPH NW IN 1944 (In the wake of Great Atlantic Hurricane) RECORDS FOR SEPTEMBER 16 HIGH 91F IN 1939,1941 LOW 39F IN 1984 PRECIP 5.12 INCHES IN 1933 (Hurricane) PEAK GUST 59 MPH SSE IN 1999 TODAY’S REPORT PREPARED BY: Matt Douglas
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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
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  • 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
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§ 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

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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
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