BLUE HILL METEOROLOGICAL OBSERVATORY
MILTON, MASSACHUSETTS
ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA

MONDAY MAY 31, 2021
ALL TIMES ARE IN EASTERN STANDARD TIME
SUNRISE: 0410E
SUNSET:  1914E

FINALLY STARTING TO DRY OUT FOLLOWING A SOAKING THIS
WEEKEND....

The day started with drizzle and fog which finally came to
an end late this morning. While it's still cloudy, the air
has begun to dry out with relative humidity finally dropping
below 90% by 1 P.M.

Wind today has been very light, especially compared to the
past couple of days of gusty winds. The average speed since
7 A.M. is only around 7 mph. Also today is the first day to
have an offshore wind direction since Thursday!

Rainfall over the weekend totaled 3.57", bringing the
monthly total over 5" and the yearly total over 20". For the
month we are now more than 1.60" above normal, however for
the year we're still running a deficit of more than 1.80".

The other big story of the weekend was the chill for this
time of year. We spent 63 consecutive hours in the 40s
between Friday evening and this morning. Also yesterday we
saw very little temperature variation with only a 1 degree
delta between the max and min temperature, 46 and 45
respectively.

The high of 46F yesterday also set a new record low maximum
for the date, beating the old record of 51F set in 1996.

Here are the rankings for coldest May 30th maximum temperatures
as compiled by our Chief Scientist Mike Iacono...

BHO Coldest May 30 Daily Maximum Temperature, deg F (1885-2021):

1) 46 in 2021
2) 51 in 1996
3) 52 in 1971
4) 53 in 1901
5) 54 in 1918
6) 55 in 1917
7) 56 in 1938

The high so far today is 56F, which is 15 degrees below
the normal high of 71F. The low since midnight is 46F,
which is 6 degrees below the daily normal low of 52F.


Today's Observations:

7 A.M.
Weather: Sky obscured, vertical visibility 200 ft, light drizzle
Temperature: 48F; Dew Point: 48F; Relative Humidity: 100%
Wind: NNW @ 7 kts
Sea-level pressure: 30.15 in. Hg; rising, then more slowly
Visibility: 1/4 mile, fog
6-hr Max temp: 48F
6-hr Min temp: 46F
24-hr Precip: 1.03 ins.
BHO SA 1155 X W2 1/4L-F 211/48/48/3407/015/ 8//// 51014
6017/ 70103 10048 20046

10 A.M.
Weather: Overcast Stratus Fractus, light drizzle
Temperature: 52F; Dew Point: 51F; Relative Humidity: 97%
Wind: N @ 8 kts
Sea-level pressure: 30.13 in Hg; steady, then falling
Visibility: 15 miles, thin fog
3-hr Precip: 0.02 ins.
BHO SA 1455 E4 OVC 15L- 203/52/51/3508/013/ THN F ALQDS
PCPN VRY LGT L-B50/ 8/6// 58008 6002/

1 P.M.
Weather: Broken stratus fractus, overcast stratus
Temperature: 55F, Dew point: 52F; Relative Humidity: 89%
Wind: WNW @ 6 kts
Sea-level pressure: 30.12 in Hg; falling, then more slowly
Visibility: 30 miles
6-hr Max temp: 56F
6-hr Min temp: 48F
6-hr Precip: 0.02 ins.
BHO SA 1755 E9 BKN 12 OVC 30 200/55/52/2906/012/ 8/6//
56003 6002/ 10056 20048

SUMMARY FOR SUNDAY, MAY 30, 2021

TEMPERATURE (DEGREES F)
MAX.......46     NORMAL.....70
MIN.......45     NORMAL.....52
MEAN......46     NORMAL.....61

DEPARTURE FROM 30-YEAR (1981-2010) NORMAL.......-15
TOTAL DEPARTURE FOR THE MONTH...................+45 [+1.3 DEGREES/DAY]

HEATING DEGREE DAYS (SEASON JUL THRU JUN)
TOTAL HEATING UNITS FOR YESTERDAY...............19  DEPARTURE......+14
TOTAL HEATING UNITS FOR THE MONTH..............224  DEPARTURE......-39
TOTAL HEATING UNITS FOR THE SEASON............5565  DEPARTURE.....-733
TOTAL HEATING UNITS LAST SEASON TO DATE.......5803  DEPARTURE.....-238

COOLING DEGREE DAYS (SEASON JAN THRU DEC)
TOTAL COOLING UNITS FOR YESTERDAY............... 0  DEPARTURE.......-1
TOTAL COOLING UNITS FOR THE MONTH...............29  DEPARTURE.......+8
TOTAL COOLING UNITS FOR THE SEASON..............29  DEPARTURE.......+6
TOTAL COOLING UNITS LAST SEASON TO DATE.........32  DEPARTURE.......-3

PEAK WIND GUST (MPH):
                     420C/Official..............37 NE  @ 10:43 A.M.
                     AEROVANE (south tower).....40 NE  @  4:57 P.M.
                     ASOS.......................39 NE  @ 10:43 A.M.
                     DAVIS #1...................37 ENE @  9:25 A.M.
                     DAVIS #2 (south tower).....38 NE  @ 12:28 P.M.
                     RMY........................40     @  9:24 A.M.
                     VECTOR.....................45     @  2:35 P.M.
                     MERLIN.....................38

FASTEST MILE:
CONTACTING ANEMOMETER/OFFICIAL..................25 NE  @ 10:42 A.M.
MAXIMUM 2-MINUTE ASOS AVERAGE...................24 NE  @ 12:29 P.M.
MAXIMUM 2-MINUTE DAVIS #1 AVERAGE...............26 ENE @ 12:29 P.M.
MAXIMUM 2-MINUTE DAVIS #2 AVERAGE...............25 ENE @ 10:37 A.M.
MAXIMUM 2-MINUTE RMY AVERAGE....................24 E   @ 12:26 P.M.
MAXIMUM 2-MINUTE VECTOR AVERAGE.................23     @ 12:26 P.M.

AVERAGE WIND SPEED AND DIRECTION:
                     CONTACTING/OFFICIAL.......15.9 NE [381 total miles]
                     ASOS......................15.1
                     DAVIS #1..................16.1 ENE
                     DAVIS #2..................16.1 ENE
                     RMY.......................14.6 E
                     VECTOR....................15.2


PRECIPITATION (INCHES) THROUGH THIS MORNING (EST):
TOTAL PRECIPITATION 24 HRS ENDING 7 A.M.......1.03  DEPARTURE....+0.88
                             ASOS.............1.06
TOTAL PRECIPITATION FOR THE MONTH.............5.58  DEPARTURE....+1.63
                             ASOS.............5.56
TOTAL PRECIPITATION FOR THE YEAR.............20.64  DEPARTURE....-1.86
                              ASOS...........20.84


PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA
DATE: MAX/MIN/MEAN/DEP/PRECIP/SNOW/SUN(MIN.)/SUN(%)/PEAK GUST/AERO/RMY GUST
AERO: Aerovane wind recording system gust
RMY:  R.M. Young wind gust recording system
TSTM: Thunderstorm day (thunder heard some time during day)
....: Data not yet available, records not finalized
M:    Missing data

05/01   62/38/50/-3/0.06/0.0/659/78       31 WNW  AERO 35 WNW  RMY 40
05/02   76/48/62/+9/0.01/0.0/220/26       41 SW   AERO 41 SW   RMY 46
05/03   67/48/58/+5/0.07/0.0/400/47       21 E    AERO 20 E    RMY 20
05/04   50/44/47/-7/0.78/0.0/000/00       36 NNE  AERO 32 NNE  RMY 37
05/05   48/44/46/-8/0.47/0.0/000/00       18 ESE  AERO 14 ESE  RMY 17
05/06   64/45/55/+1/0.00/0.0/780/91       33 NW   AERO 38 NNW  RMY 39
05/07   61/43/52/-3/0.00/0.0/516/60       28 ESE  AERO 22 ESE  RMY 26
05/08   54/40/47/-8/0.00/0.0/069/08       24 SSW  AERO 23 SSW  RMY 25
05/09   66/42/54/-1/T/0.0/579/67          30 SW   AERO 29 SW   RMY 34
05/10   60/45/53/-2/0.39/0.0/078/09       21 W    AERO 20 W    RMY 20
05/11   63/45/54/-2/0.00/0.0/764/88       38 WNW  AERO 41 WNW  RMY 41
05/12   65/41/53/-3/0.00/0.0/722/83       28 NW   AERO M  M    RMY 31
05/13   69/45/57/+1/0.00/0.0/759/87       22 WNW  AERO 21 WNW  RMY 21
05/14   76/49/63/+8/0.00/0.0/725/83       23 WNW  AERO 23 WNW  RMY 25
05/15   75/55/65/+8/0.01/0.0/569/65       24 SSE  AERO 26 SSE  RMY 26
05/16   78/54/66/+9/0.01/0.0/483/55       36 W    AERO 37 W    RMY 42
05/17   77/52/65/+8/0.00/0.0/722/82       20 SSW  AERO 21 SSW  RMY 21
05/18   81/54/68/+10/T/0.0/600/68         32 W    AERO 30 W    RMY 32
05/19   75/55/65/+7/0.00/0.0/778/88       25 NE   AERO 23 NNE  RMY 27
05/20   75/52/64/+6/0.00/0.0/842/95       18 ESE  AERO 18 ESE  RMY 19
05/21   78/50/64/+5/T/0.0/524/59          23 S    AERO 22 S    RMY 26
05/22   87/56/72/+13/T/0.0/285/32         25 WNW  AERO 21 WNW  RMY 24
05/23   87/58/73/+14/T/0.0/687/77         38 NNW  AERO 37 NNW  RMY 40
05/24   70/49/60/+1/0.00/0.0/.../..       30 S    AERO 35 S    RMY 33
05/25   75/47/61/+1/0.00/0.0/.../..       31 SW   AERO 35 SW   RMY 34
05/26   86/57/72/+12/0.21/0.0/.../..      30 S    AERO 36 S    RMY 35 TSTM
05/27   79/57/68/+8/0.02/0.0/.../..       25 N    AERO 25 WNW  RMY 27
05/28   58/43/51/-10/1.00/0.0/.../..      28 ENE  AERO 32 ENE  RMY 27
05/29   46/42/44/-17/1.50/0.0/.../..      44 ENE  AERO 47 ENE  RMY 50
05/30   46/45/46/-15/0.87/0.0/.../..      37 NE   AERO 40 NE   RMY 40

05/31   The low since midnight is 46F, the daily normal low is 52F
 

DAILY EXTREMES
Temperature and precipitation records back to 1885, and
wind records back to 1940 (e = estimated)

RECORDS FOR MAY 31
HIGH 92F IN 1944,1987,2013
LOW 35F IN 1961
PRECIP 5.02 INS 1984 (RECORD FOR MAY)
PEAK GUST 54e MPH WNW IN 1945

RECORDS FOR JUNE 1
HIGH 90F IN 1937,2013
LOW 36F IN 1945 [Record for month]
PRECIP 2.28 INS IN 1992
PEAK GUST 51e MPH SE IN 1952

TODAY'S REPORT PREPARED BY: Matt Douglas