This page made possible by the sponsorship of:

Putman Mountain Observatory
.

Putman Mountain Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Putman Mountain Observatory clear sky chart from 2005-11-06 to 2024-01-27.

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
46%
23866
27%
74497
17%
23807
57%
23807
36%
41219

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
34%
950
31%
2458
11%
946
47%
946
38%
1468
January11th to 20thNight
33%
950
30%
2470
11%
950
46%
950
37%
1468
January21st to endNight
31%
863
33%
2503
12%
863
48%
863
33%
1475
February1st to 10thNight
29%
720
29%
2160
11%
720
44%
720
31%
1253
February11th to 20thNight
27%
704
24%
2098
9%
700
38%
700
30%
1237
February21st to endNight
20%
592
29%
1776
5%
592
40%
592
27%
1050
March1st to 10thNight
27%
619
26%
2059
9%
619
43%
619
27%
1192
March11th to 20thNight
31%
540
24%
1980
14%
540
45%
540
25%
1138
March21st to endNight
26%
594
28%
2178
13%
594
46%
594
31%
1120
April1st to 10thNight
24%
540
27%
1980
10%
540
48%
540
30%
1070
April11th to 20thNight
23%
533
25%
1853
10%
533
43%
533
27%
1055
April21st to endNight
25%
540
30%
1706
12%
540
48%
540
33%
971
May1st to 10thNight
30%
540
28%
1620
15%
540
47%
540
33%
940
May11th to 20thNight
40%
531
22%
1594
17%
531
50%
531
34%
940
May21st to endNight
42%
583
23%
1746
15%
582
56%
582
34%
1027
June1st to 10thNight
66%
540
25%
1620
22%
540
75%
540
50%
813
June11th to 20thNight
55%
540
26%
1620
22%
540
66%
540
53%
773
June21st to endNight
67%
540
26%
1620
27%
540
72%
540
44%
867
July1st to 10thNight
72%
525
19%
1575
20%
525
75%
525
37%
895
July11th to 20thNight
82%
522
30%
1566
32%
522
86%
522
56%
737
July21st to endNight
83%
591
28%
1673
30%
558
88%
558
57%
789
August1st to 10thNight
88%
537
31%
1667
36%
534
90%
534
64%
712
August11th to 20thNight
78%
534
26%
1778
31%
534
80%
534
40%
932
August21st to endNight
81%
594
22%
2020
25%
594
82%
594
39%
1051
September1st to 10thNight
73%
540
22%
1980
25%
540
76%
540
35%
1050
September11th to 20thNight
71%
540
22%
1980
24%
540
73%
540
30%
1135
September21st to endNight
71%
540
28%
1980
27%
540
76%
540
36%
1024
October1st to 10thNight
73%
540
36%
1980
35%
540
78%
540
45%
898
October11th to 20thNight
56%
596
35%
2036
24%
596
66%
596
37%
1084
October21st to endNight
44%
792
33%
2376
17%
792
55%
792
37%
1314
November1st to 10thNight
51%
758
31%
2238
17%
758
60%
758
39%
1245
November11th to 20thNight
47%
950
29%
2470
13%
950
55%
950
42%
1429
November21st to endNight
36%
950
29%
2470
12%
950
46%
950
32%
1549
December1st to 10thNight
42%
950
32%
2470
15%
950
52%
950
39%
1472
December11th to 20thNight
33%
949
27%
2894
11%
948
43%
948
28%
1817
December21st to endNight
35%
1039
19%
4303
12%
1026
46%
1026
26%
2229

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
9%42443445%7%52%
75000
Night
8%42342445%8%57%
75074
TransparencyDay
33%5%10%21%21%11%
74725
Night
29%5%10%21%21%13%
74869
SeeingDay
11%8%23%31%21%5%
13787
Night
11%8%31%36%13%1
23874

By Month

Percentage Cloud Cover SE (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
10%6%24323345%58%
1707
11th to 20thDay
14%5%23324445%53%
1710
21st to endDay
11%425%423346%55%
2011
February1st to 10thDay
14%5%25%323346%53%
1800
11th to 20thDay
14%6%2332445%6%50%
1749
21st to endDay
14%5%3332335%5%54%
1480
March1st to 10thDay
13%7%25%5%345%48%45%
1899
11th to 20thDay
12%5%25%5%335%46%50%
1980
21st to endDay
9%6%24324446%56%
2178
April1st to 10thDay
10%5%25%5%35%448%48%
1980
11th to 20thDay
13%6%35%433446%48%
2052
21st to endDay
10%4245%34346%54%
2252
May1st to 10thDay
10%5%25%5%345%7%9%45%
2340
11th to 20thDay
11%7%35%5%45%5%5%6%43%
2302
21st to endDay
10%5%25%6%36%7%7%9%41%
2531
June1st to 10thDay
43235%345%7%10%54%
2340
11th to 20thDay
3323335%5%6%10%57%
2340
21st to endDay
6%324445%7%7%10%49%
2340
July1st to 10thDay
7%5%25%6%36%7%7%9%43%
2340
11th to 20thDay
4213435%5%6%9%58%
2340
21st to endDay
42135%35%5%5%11%57%
2546
August1st to 10thDay
111333445%9%67%
2257
11th to 20thDay
7%4245%45%5%6%9%49%
2123
21st to endDay
43246%46%7%7%11%47%
2336
September1st to 10thDay
9%426%436%448%50%
1980
11th to 20thDay
11%5%35%435%6%5%7%46%
1980
21st to endDay
9%214435%5%6%7%54%
1980
October1st to 10thDay
5%424323448%60%
1980
11th to 20thDay
10%5%1342335%5%59%
1904
21st to endDay
10%424323345%62%
1980
November1st to 10thDay
10%5%3432345%7%54%
1837
11th to 20thDay
8%3144235%5%7%57%
1710
21st to endDay
13%6%245%33335%52%
1710
December1st to 10thDay
13%5%23424347%53%
1710
11th to 20thDay
12%6%25%5%2345%6%50%
2161
21st to endDay
10%6%13323335%59%
3135
January1st to 10thNight
12%5%23423436%58%
2458
11th to 20thNight
12%5%24323346%57%
2470
21st to endNight
13%6%24423446%54%
2503
February1st to 10thNight
12%5%24423347%54%
2160
11th to 20thNight
14%6%24223346%54%
2098
21st to endNight
13%42432345%7%52%
1776
March1st to 10thNight
11%5%25%33436%9%49%
2059
11th to 20thNight
10%5%235%35%45%7%51%
1980
21st to endNight
7%31333445%8%58%
2178
April1st to 10thNight
7%42443446%9%54%
1980
11th to 20thNight
8%5%3443445%7%53%
1853
21st to endNight
9%32342345%8%57%
1706
May1st to 10thNight
6%4235%345%5%10%53%
1620
11th to 20thNight
8%425%425%5%5%10%51%
1593
21st to endNight
6%32443348%13%50%
1745
June1st to 10thNight
221233447%10%64%
1620
11th to 20thNight
311232346%9%67%
1620
21st to endNight
32233235%6%9%60%
1620
July1st to 10thNight
432443448%11%51%
1620
11th to 20thNight
221232245%10%69%
1620
21st to endNight
221232447%11%63%
1772
August1st to 10thNight
111123448%75%
1677
11th to 20thNight
4323435%6%6%9%54%
1778
21st to endNight
42135%345%6%12%53%
2020
September1st to 10thNight
6%424425%5%6%8%55%
1980
11th to 20thNight
10%423435%5%6%10%48%
1980
21st to endNight
8%2133345%5%8%58%
1980
October1st to 10thNight
421232435%8%67%
1980
11th to 20thNight
10%313323446%59%
2036
21st to endNight
11%5%2332334462%
2376
November1st to 10thNight
10%313323346%61%
2238
11th to 20thNight
6%323424347%61%
2470
21st to endNight
14%423434446%51%
2470
December1st to 10thNight
10%42332345%6%56%
2470
11th to 20thNight
9%7%35%4345%45%50%
3036
21st to endNight
9%5%24333345%59%
4532

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
31%3418%28%16%
1708
11th to 20thDay
35%45%16%25%16%
1710
21st to endDay
33%36%13%28%17%
2011
February1st to 10thDay
35%36%14%22%20%
1800
11th to 20thDay
36%45%19%19%16%
1759
21st to endDay
35%35%17%22%19%
1480
March1st to 10thDay
40%48%15%20%12%
1899
11th to 20thDay
37%48%14%19%18%
1980
21st to endDay
32%49%18%22%14%
2178
April1st to 10thDay
37%5%8%18%19%13%
1980
11th to 20thDay
39%37%16%22%12%
2052
21st to endDay
35%45%23%22%11%
2252
May1st to 10thDay
36%6%12%15%22%9%
2340
11th to 20thDay
43%5%9%19%20%5%
2306
21st to endDay
41%7%11%21%18%2
2531
June1st to 10thDay
27%5%13%29%21%5%
2340
11th to 20thDay
25%7%12%28%22%6%
2340
21st to endDay
31%8%13%23%19%6%
2340
July1st to 10thDay
37%9%13%27%12%1
2276
11th to 20thDay
22%6%16%29%22%4
2271
21st to endDay
20%6%22%35%16%1
2405
August1st to 10thDay
17%5%13%41%22%2
2243
11th to 20thDay
31%5%16%29%14%4
2123
21st to endDay
32%7%15%27%14%4
2336
September1st to 10thDay
34%7%10%22%18%8%
1980
11th to 20thDay
38%6%13%19%19%5%
1980
21st to endDay
30%6%9%22%22%12%
1980
October1st to 10thDay
25%5%11%21%27%11%
1980
11th to 20thDay
32%46%15%26%18%
1904
21st to endDay
29%3417%26%21%
1980
November1st to 10thDay
34%5%7%21%22%12%
1837
11th to 20thDay
28%5%8%19%22%17%
1710
21st to endDay
38%35%17%23%15%
1710
December1st to 10thDay
34%37%21%25%11%
1710
11th to 20thDay
37%38%12%23%17%
2159
21st to endDay
31%2415%28%19%
3135
January1st to 10thNight
31%3416%25%21%
2458
11th to 20thNight
31%35%18%24%19%
2470
21st to endNight
35%35%15%23%20%
2503
February1st to 10thNight
35%46%13%23%20%
2160
11th to 20thNight
34%45%17%21%18%
2098
21st to endNight
35%46%13%21%21%
1776
March1st to 10thNight
35%5%9%15%24%12%
2059
11th to 20thNight
36%5%8%15%18%18%
1980
21st to endNight
28%5%12%20%19%16%
2178
April1st to 10thNight
31%5%10%21%19%15%
1980
11th to 20thNight
34%5%8%16%21%16%
1853
21st to endNight
30%6%9%21%22%11%
1706
May1st to 10thNight
30%7%10%22%20%11%
1620
11th to 20thNight
33%5%13%25%19%5%
1594
21st to endNight
30%8%15%29%16%2
1746
June1st to 10thNight
18%6%16%34%22%3
1620
11th to 20thNight
16%6%16%33%22%6%
1620
21st to endNight
23%6%15%30%21%4
1620
July1st to 10thNight
28%8%21%29%12%2
1575
11th to 20thNight
14%6%21%31%25%3
1566
21st to endNight
14%5%26%37%16%1
1673
August1st to 10thNight
10%5%19%41%23%1
1667
11th to 20thNight
25%6%20%30%14%4
1778
21st to endNight
25%6%23%27%15%4
2020
September1st to 10thNight
26%8%14%24%19%8%
1980
11th to 20thNight
33%7%16%23%17%5%
1980
21st to endNight
27%6%12%22%21%12%
1980
October1st to 10thNight
19%6%14%26%23%12%
1980
11th to 20thNight
29%48%16%24%19%
2036
21st to endNight
29%35%16%24%22%
2376
November1st to 10thNight
28%5%6%21%25%15%
2238
11th to 20thNight
26%5%6%22%22%18%
2470
21st to endNight
36%48%15%21%16%
2470
December1st to 10thNight
31%48%19%25%13%
2470
11th to 20thNight
38%35%13%20%20%
3037
21st to endNight
31%3415%29%17%
4532

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
17%18%37%23%5%1
270
11th to 20thDay
21%13%33%24%7%1
270
21st to endDay
15%17%41%23%4
282
February1st to 10thDay
20%16%35%23%7%
240
11th to 20thDay
23%17%38%18%4
240
21st to endDay
23%20%35%18%4
198
March1st to 10thDay
19%15%42%20%3
240
11th to 20thDay
15%21%36%20%7%
240
21st to endDay
16%19%44%17%5%
264
April1st to 10thDay
15%21%42%19%3
240
11th to 20thDay
16%18%39%21%5%
330
21st to endDay
14%17%44%19%7%
512
May1st to 10thDay
12%12%40%27%8%
603
11th to 20thDay
16%9%32%29%11%2
625
21st to endDay
13%8%28%35%15%2
679
June1st to 10thDay
5%320%43%24%4
630
11th to 20thDay
4218%53%19%3
630
21st to endDay
6%114%43%31%6%
630
July1st to 10thDay
7%29%38%33%11%
621
11th to 20thDay
45%43%41%8%
618
21st to endDay
315%39%40%12%
684
August1st to 10thDay
3440%41%12%
555
11th to 20thDay
9%16%32%38%14%
437
21st to endDay
5%16%27%44%16%
455
September1st to 10thDay
9%1424%42%20%
270
11th to 20thDay
7%7%26%43%17%
270
21st to endDay
13%16%31%37%12%
270
October1st to 10thDay
7%413%34%35%7%
270
11th to 20thDay
11%5%25%36%21%3
270
21st to endDay
21%14%25%26%14%
297
November1st to 10thDay
19%6%27%35%11%2
270
11th to 20thDay
15%14%26%30%9%6%
270
21st to endDay
22%16%33%19%7%3
270
December1st to 10thDay
15%10%33%29%10%3
270
11th to 20thDay
17%17%36%21%8%
270
21st to endDay
16%13%35%25%10%
297
January1st to 10thNight
15%10%39%30%6%
950
11th to 20thNight
16%11%36%31%6%
950
21st to endNight
15%12%38%28%6%
863
February1st to 10thNight
17%11%40%26%6%
720
11th to 20thNight
17%12%42%25%3
704
21st to endNight
17%17%45%20%1
592
March1st to 10thNight
14%16%40%28%2
619
11th to 20thNight
15%10%42%28%5%
540
21st to endNight
10%13%49%24%4
594
April1st to 10thNight
8%13%52%25%2
540
11th to 20thNight
11%15%48%23%3
533
21st to endNight
10%10%53%20%6%
540
May1st to 10thNight
9%11%47%29%4
540
11th to 20thNight
9%8%40%32%10%1
531
21st to endNight
8%6%40%34%11%1
584
June1st to 10thNight
2128%49%20%1
540
11th to 20thNight
4236%46%11%
540
21st to endNight
5%220%48%22%2
540
July1st to 10thNight
6%212%53%26%2
525
11th to 20thNight
3110%60%25%1
522
21st to endNight
39%60%25%3
591
August1st to 10thNight
18%59%29%3
537
11th to 20thNight
5%9%53%29%4
534
21st to endNight
5%16%50%32%6%
594
September1st to 10thNight
9%111%43%31%5%
540
11th to 20thNight
11%19%40%35%3
540
21st to endNight
10%13%46%29%2
540
October1st to 10thNight
5%217%49%26%1
540
11th to 20thNight
13%225%44%15%2
596
21st to endNight
14%9%30%29%16%1
792
November1st to 10thNight
12%5%29%39%14%1
758
11th to 20thNight
9%9%32%37%13%1
950
21st to endNight
16%11%32%30%10%1
950
December1st to 10thNight
13%8%35%36%8%
950
11th to 20thNight
17%10%37%32%5%
950
21st to endNight
13%12%36%32%6%
1045
Page generated at 2024-01-24 08:37:32. Version ac07

Copyright 2024 Attilla Danko


Putman Mountain Observatory Clear Sky Chart |Charts Home