Stoneham
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stoneham clear sky chart from 2005-11-06 to 2024-01-16.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
27%
22734
12%
74925
6%
22685
34%
22685
14%
54970

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
13%
760
9%
2649
1%
757
21%
757
7%
2129
January11th to 20thNight
16%
744
11%
2602
4%
744
25%
744
9%
2001
January21st to endNight
22%
792
13%
2772
5%
792
33%
792
13%
1997
February1st to 10thNight
19%
720
13%
2520
5%
720
30%
720
11%
1872
February11th to 20thNight
12%
702
10%
2118
1%
700
21%
700
11%
1640
February21st to endNight
21%
592
16%
1776
7%
592
32%
592
14%
1329
March1st to 10thNight
20%
720
14%
2160
7%
720
30%
720
14%
1605
March11th to 20thNight
21%
720
13%
2076
5%
720
29%
720
14%
1546
March21st to endNight
27%
792
18%
2039
5%
792
35%
792
19%
1505
April1st to 10thNight
23%
720
12%
1800
4%
720
28%
720
15%
1416
April11th to 20thNight
26%
624
16%
1688
6%
624
32%
624
21%
1205
April21st to endNight
22%
540
15%
1620
7%
540
29%
540
15%
1187
May1st to 10thNight
28%
491
13%
1571
8%
491
35%
491
15%
1133
May11th to 20thNight
33%
354
16%
1416
16%
354
43%
354
15%
960
May21st to endNight
27%
389
11%
1515
7%
388
39%
388
16%
1017
June1st to 10thNight
33%
360
7%
1260
5%
360
38%
360
13%
905
June11th to 20thNight
41%
360
11%
1260
10%
360
46%
360
19%
836
June21st to endNight
38%
360
8%
1260
7%
360
42%
360
15%
918
July1st to 10thNight
43%
350
8%
1350
10%
350
47%
350
19%
892
July11th to 20thNight
46%
348
9%
1392
13%
348
49%
348
17%
921
July21st to endNight
47%
394
10%
1486
12%
372
51%
372
16%
1009
August1st to 10thNight
57%
358
13%
1422
14%
356
61%
356
20%
901
August11th to 20thNight
44%
516
10%
1580
8%
516
46%
516
19%
1123
August21st to endNight
42%
700
17%
1888
10%
700
45%
700
24%
1302
September1st to 10thNight
40%
720
12%
1800
5%
720
43%
720
26%
1275
September11th to 20thNight
41%
720
14%
1954
7%
720
45%
720
24%
1357
September21st to endNight
36%
720
17%
1980
10%
720
42%
720
25%
1364
October1st to 10thNight
32%
720
19%
1987
12%
720
40%
720
21%
1414
October11th to 20thNight
30%
720
11%
2311
5%
720
37%
720
14%
1725
October21st to endNight
21%
792
9%
2574
5%
792
27%
792
12%
1941
November1st to 10thNight
26%
740
13%
2407
7%
740
33%
740
13%
1742
November11th to 20thNight
26%
760
16%
2475
9%
760
35%
760
13%
1830
November21st to endNight
19%
836
10%
2818
4%
836
25%
836
10%
2201
December1st to 10thNight
19%
850
9%
2850
5%
850
24%
850
8%
2321
December11th to 20thNight
18%
850
11%
3465
5%
848
26%
848
8%
2634
December21st to endNight
13%
900
7%
5084
2%
883
21%
883
5%
3817

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
21%10%47%6%35%5%5%6%29%
74566
Night
20%11%47%6%34446%31%
75236
TransparencyDay
55%7%12%17%8%1
74271
Night
55%7%11%17%9%1
75066
SeeingDay
26%17%29%19%7%1
14103
Night
25%12%28%26%8%1
22746

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
17%16%6%10%7%445%5%6%21%
1517
11th to 20thDay
14%18%8%10%7%345%35%24%
1486
21st to endDay
10%12%6%10%7%35%6%5%6%30%
1584
February1st to 10thDay
10%15%6%13%8%5%6%5%45%24%
1440
11th to 20thDay
14%15%8%11%7%35%445%24%
1724
21st to endDay
14%14%6%11%8%3345%6%26%
1480
March1st to 10thDay
15%13%5%11%7%33445%29%
1797
11th to 20thDay
18%13%5%7%6%35%5%45%30%
1883
21st to endDay
16%13%47%7%35%445%32%
2315
April1st to 10thDay
22%15%47%6%34445%27%
2160
11th to 20thDay
22%9%35%5%34445%35%
2220
21st to endDay
24%11%36%6%34446%29%
2340
May1st to 10thDay
24%9%46%5%3446%5%32%
2402
11th to 20thDay
21%7%36%6%45%5%6%5%32%
2478
21st to endDay
23%6%36%6%36%45%6%32%
2758
June1st to 10thDay
23%7%36%6%45%6%6%8%25%
2700
11th to 20thDay
23%6%36%5%35%5%6%6%32%
2700
21st to endDay
26%9%47%6%45%5%5%7%24%
2700
July1st to 10thDay
17%7%37%7%35%6%7%8%29%
2566
11th to 20thDay
19%6%37%6%46%6%7%8%28%
2520
21st to endDay
19%7%36%6%46%7%7%8%27%
2744
August1st to 10thDay
20%8%36%7%46%6%7%9%25%
2504
11th to 20thDay
20%7%36%6%45%5%5%9%30%
2304
21st to endDay
20%7%26%6%35%6%5%7%33%
2466
September1st to 10thDay
22%7%25%5%345%6%7%34%
2160
11th to 20thDay
20%6%2442445%6%42%
2005
21st to endDay
26%6%245%345%45%36%
1980
October1st to 10thDay
23%9%37%5%345%45%32%
1972
11th to 20thDay
29%10%37%5%45%45%5%23%
1648
21st to endDay
30%11%45%5%35%5%45%24%
1782
November1st to 10thDay
21%12%5%6%6%43446%29%
1671
11th to 20thDay
23%14%5%10%6%34445%24%
1701
21st to endDay
21%18%5%8%6%3444422%
1359
December1st to 10thDay
25%16%5%9%7%3433422%
1330
11th to 20thDay
22%14%5%9%6%4434327%
1668
21st to endDay
20%18%6%8%42344426%
2502
January1st to 10thNight
15%19%7%10%9%34335%20%
2649
11th to 20thNight
16%16%7%10%6%44445%25%
2602
21st to endNight
9%12%6%9%8%5%7%5%5%5%29%
2772
February1st to 10thNight
11%13%6%11%8%46%5%46%27%
2520
11th to 20thNight
13%17%6%11%7%45%445%25%
2116
21st to endNight
15%14%5%10%6%3435%5%29%
1776
March1st to 10thNight
14%11%5%8%8%36%45%6%30%
2150
11th to 20thNight
17%14%36%5%46%5%5%5%29%
2075
21st to endNight
16%11%46%7%3445%5%36%
2039
April1st to 10thNight
23%14%47%5%34445%28%
1800
11th to 20thNight
20%7%46%5%25%46%7%35%
1688
21st to endNight
24%10%38%433247%33%
1620
May1st to 10thNight
25%8%35%5%25%5%4433%
1571
11th to 20thNight
23%7%35%5%45%445%36%
1415
21st to endNight
24%6%245%34447%38%
1514
June1st to 10thNight
21%8%36%5%47%6%6%7%28%
1260
11th to 20thNight
21%5%345%35%47%8%37%
1260
21st to endNight
26%7%36%6%43447%30%
1260
July1st to 10thNight
18%6%345%35%5%6%9%36%
1390
11th to 20thNight
18%6%35%6%445%5%9%35%
1440
21st to endNight
18%7%37%5%345%6%7%35%
1574
August1st to 10thNight
18%4244445%6%9%39%
1432
11th to 20thNight
18%7%36%5%445%6%7%34%
1580
21st to endNight
19%5%25%435%45%6%40%
1888
September1st to 10thNight
20%6%35%5%2445%6%40%
1800
11th to 20thNight
21%6%3442435%5%42%
1954
21st to endNight
22%7%24422446%42%
1980
October1st to 10thNight
21%8%35%5%34445%37%
1987
11th to 20thNight
27%9%35%5%35%45%5%31%
2311
21st to endNight
28%10%37%4345%5%5%27%
2574
November1st to 10thNight
20%12%46%5%3346%7%29%
2407
11th to 20thNight
22%11%48%5%34445%31%
2475
21st to endNight
22%15%6%8%5%34435%25%
2818
December1st to 10thNight
22%16%6%10%7%34345%20%
2850
11th to 20thNight
22%14%5%9%6%3444424%
3531
21st to endNight
22%19%6%8%6%2333326%
5158

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
64%6%10%12%7%1
1518
11th to 20thDay
63%5%10%13%7%2
1486
21st to endDay
53%6%9%17%13%1
1584
February1st to 10thDay
61%7%9%13%9%2
1440
11th to 20thDay
61%5%10%11%10%1
1733
21st to endDay
60%48%18%8%3
1480
March1st to 10thDay
55%7%9%15%11%3
1800
11th to 20thDay
56%6%10%15%12%2
1883
21st to endDay
54%6%10%16%11%3
2315
April1st to 10thDay
61%5%11%11%9%4
2160
11th to 20thDay
50%5%10%21%11%3
2220
21st to endDay
56%6%10%14%11%3
2340
May1st to 10thDay
51%7%11%15%13%2
2402
11th to 20thDay
51%8%10%19%10%1
2482
21st to endDay
52%9%10%18%11%1
2758
June1st to 10thDay
54%10%12%16%7%1
2700
11th to 20thDay
50%7%15%17%10%1
2700
21st to endDay
59%8%11%14%8%
2700
July1st to 10thDay
49%11%16%19%5%
2496
11th to 20thDay
49%11%16%18%6%
2445
21st to endDay
51%12%14%17%6%
2591
August1st to 10thDay
52%12%18%15%3
2490
11th to 20thDay
49%9%18%18%6%
2304
21st to endDay
48%9%14%21%8%
2466
September1st to 10thDay
47%8%15%20%9%
2160
11th to 20thDay
41%7%18%24%9%
2005
21st to endDay
50%7%13%22%9%
1980
October1st to 10thDay
53%6%12%21%8%1
1972
11th to 20thDay
61%9%13%14%3
1648
21st to endDay
63%6%10%15%5%1
1782
November1st to 10thDay
57%7%12%17%7%
1671
11th to 20thDay
63%5%10%16%5%1
1701
21st to endDay
65%7%11%11%5%1
1359
December1st to 10thDay
67%5%10%12%6%
1330
11th to 20thDay
61%6%8%17%9%
1668
21st to endDay
62%6%10%14%7%2
2502
January1st to 10thNight
67%5%8%13%6%1
2649
11th to 20thNight
61%6%9%14%8%2
2602
21st to endNight
56%5%9%16%13%1
2772
February1st to 10thNight
58%6%8%17%10%1
2520
11th to 20thNight
61%5%10%12%10%1
2118
21st to endNight
57%5%8%15%13%2
1776
March1st to 10thNight
55%7%10%15%11%2
2160
11th to 20thNight
55%6%11%14%11%2
2076
21st to endNight
51%5%10%19%11%4
2039
April1st to 10thNight
59%5%9%12%12%3
1800
11th to 20thNight
48%7%9%21%13%2
1688
21st to endNight
54%6%8%16%13%2
1620
May1st to 10thNight
53%7%10%14%13%2
1571
11th to 20thNight
50%7%10%18%14%1
1416
21st to endNight
48%7%11%18%14%2
1515
June1st to 10thNight
52%9%13%17%8%1
1260
11th to 20thNight
45%8%13%21%11%3
1260
21st to endNight
54%7%12%16%11%
1260
July1st to 10thNight
43%10%19%20%7%
1350
11th to 20thNight
46%9%17%21%7%1
1392
21st to endNight
48%9%15%21%7%
1486
August1st to 10thNight
41%9%20%25%5%
1422
11th to 20thNight
46%11%19%17%7%
1580
21st to endNight
43%8%13%29%7%
1888
September1st to 10thNight
44%8%14%23%11%1
1800
11th to 20thNight
43%8%16%25%7%1
1954
21st to endNight
44%6%14%24%11%
1980
October1st to 10thNight
49%6%10%23%11%1
1987
11th to 20thNight
54%9%14%18%6%
2311
21st to endNight
57%7%13%15%7%1
2574
November1st to 10thNight
54%6%14%19%6%1
2407
11th to 20thNight
56%6%12%16%10%
2475
21st to endNight
63%6%10%14%6%1
2818
December1st to 10thNight
68%5%10%12%5%
2850
11th to 20thNight
62%5%9%14%10%
3532
21st to endNight
64%5%8%14%7%2
5158

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
24%18%36%18%4
180
11th to 20thDay
22%26%34%15%3
172
21st to endDay
17%20%41%16%5%1
176
February1st to 10thDay
30%28%36%5%11
160
11th to 20thDay
22%26%36%14%3
400
21st to endDay
25%24%30%18%4
346
March1st to 10thDay
24%22%32%18%5%
420
11th to 20thDay
26%21%30%15%6%1
420
21st to endDay
24%23%26%19%7%1
462
April1st to 10thDay
30%20%28%17%5%
420
11th to 20thDay
29%19%27%18%5%2
412
21st to endDay
31%17%34%13%41
420
May1st to 10thDay
31%18%31%15%41
423
11th to 20thDay
24%17%33%19%6%1
447
21st to endDay
28%21%29%16%6%
518
June1st to 10thDay
26%16%30%21%7%
630
11th to 20thDay
26%14%27%23%9%1
630
21st to endDay
27%11%30%21%9%1
630
July1st to 10thDay
21%14%33%23%9%
491
11th to 20thDay
20%12%34%25%8%1
444
21st to endDay
22%13%31%25%9%1
488
August1st to 10thDay
23%9%31%24%11%3
446
11th to 20thDay
21%9%26%29%12%2
439
21st to endDay
24%15%24%19%13%5%
495
September1st to 10thDay
24%13%26%22%11%4
450
11th to 20thDay
24%12%27%21%13%2
450
21st to endDay
25%14%27%19%10%5%
450
October1st to 10thDay
25%15%28%20%10%1
450
11th to 20thDay
33%15%24%18%8%1
374
21st to endDay
38%17%25%16%4
396
November1st to 10thDay
34%16%25%19%5%1
365
11th to 20thDay
28%19%27%17%7%1
361
21st to endDay
32%23%29%15%1
180
December1st to 10thDay
32%15%27%18%8%1
180
11th to 20thDay
33%21%27%14%41
180
21st to endDay
31%21%31%13%4
198
January1st to 10thNight
23%17%33%23%4
760
11th to 20thNight
25%17%31%22%6%
744
21st to endNight
16%13%35%30%6%1
792
February1st to 10thNight
18%17%35%26%4
720
11th to 20thNight
23%16%39%18%4
703
21st to endNight
22%16%33%24%5%
592
March1st to 10thNight
21%14%38%24%4
720
11th to 20thNight
23%19%32%19%6%1
720
21st to endNight
21%16%30%26%6%1
792
April1st to 10thNight
30%16%26%22%6%
720
11th to 20thNight
25%11%32%26%5%
624
21st to endNight
29%16%29%20%6%
540
May1st to 10thNight
27%11%29%27%5%
491
11th to 20thNight
23%10%28%31%7%1
354
21st to endNight
29%7%31%24%8%1
389
June1st to 10thNight
24%8%28%33%7%
360
11th to 20thNight
22%5%24%37%12%
360
21st to endNight
26%423%37%10%1
360
July1st to 10thNight
20%428%35%12%1
350
11th to 20thNight
20%323%39%15%1
348
21st to endNight
19%6%19%42%14%1
394
August1st to 10thNight
19%414%44%20%
358
11th to 20thNight
19%5%22%37%16%1
516
21st to endNight
20%7%24%32%15%2
700
September1st to 10thNight
21%6%28%31%14%1
720
11th to 20thNight
22%8%24%28%16%2
720
21st to endNight
24%9%25%28%14%1
720
October1st to 10thNight
26%9%27%29%9%1
720
11th to 20thNight
30%9%26%25%10%
720
21st to endNight
33%12%28%22%5%
792
November1st to 10thNight
27%14%26%25%7%1
740
11th to 20thNight
28%16%24%24%8%1
760
21st to endNight
29%16%28%20%5%1
836
December1st to 10thNight
32%13%25%23%8%
850
11th to 20thNight
25%20%28%22%5%1
850
21st to endNight
30%18%28%19%4
911
Page generated at 2024-01-13 19:28:34. Version ac07

Copyright 2024 Attilla Danko


Stoneham Clear Sky Chart |Charts Home