Adirondack Public Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Adirondack Public Observatory clear sky chart from 2005-11-06 to 2024-01-31.

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
24%
22758
11%
74992
7%
22717
29%
22717
11%
57787

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
9%
760
6%
2649
3%
757
12%
757
4%
2326
January11th to 20thNight
9%
760
6%
2660
3%
760
13%
760
5%
2319
January21st to endNight
13%
835
8%
2878
4%
835
18%
835
6%
2373
February1st to 10thNight
8%
720
5%
2340
1%
720
13%
720
5%
2033
February11th to 20thNight
10%
703
8%
2189
2%
700
17%
700
6%
1831
February21st to endNight
11%
592
10%
1776
3%
592
20%
592
7%
1478
March1st to 10thNight
15%
720
11%
2160
6%
720
22%
720
10%
1714
March11th to 20thNight
15%
720
12%
2048
4%
720
23%
720
11%
1613
March21st to endNight
21%
792
18%
2012
6%
792
29%
792
15%
1534
April1st to 10thNight
17%
720
13%
1800
3%
720
23%
720
13%
1417
April11th to 20thNight
22%
711
12%
1775
4%
711
25%
711
15%
1383
April21st to endNight
22%
635
13%
1715
5%
635
27%
635
15%
1305
May1st to 10thNight
25%
413
13%
1493
10%
413
32%
413
12%
1079
May11th to 20thNight
33%
354
17%
1416
14%
354
43%
354
16%
916
May21st to endNight
37%
388
11%
1551
11%
388
45%
388
16%
1016
June1st to 10thNight
35%
360
10%
1440
9%
360
44%
360
13%
1005
June11th to 20thNight
40%
360
12%
1440
15%
360
46%
360
18%
929
June21st to endNight
35%
360
10%
1440
11%
360
42%
360
14%
983
July1st to 10thNight
48%
350
13%
1400
17%
350
55%
350
22%
837
July11th to 20thNight
51%
348
15%
1392
18%
348
57%
348
21%
864
July21st to endNight
48%
394
14%
1486
15%
372
53%
372
20%
937
August1st to 10thNight
51%
358
16%
1422
17%
356
54%
356
21%
877
August11th to 20thNight
47%
614
14%
1678
9%
614
50%
614
24%
1199
August21st to endNight
42%
792
16%
1980
8%
792
44%
792
26%
1399
September1st to 10thNight
41%
720
13%
1800
6%
720
43%
720
26%
1264
September11th to 20thNight
47%
720
21%
1850
13%
720
50%
720
31%
1225
September21st to endNight
39%
720
20%
1980
15%
720
43%
720
24%
1377
October1st to 10thNight
29%
720
13%
2132
10%
720
34%
720
15%
1595
October11th to 20thNight
27%
720
11%
2160
7%
720
32%
720
13%
1651
October21st to endNight
17%
792
9%
2560
5%
792
22%
792
8%
2086
November1st to 10thNight
21%
740
11%
2407
7%
740
27%
740
12%
1832
November11th to 20thNight
17%
760
14%
2531
9%
760
24%
760
10%
1977
November21st to endNight
15%
760
8%
2660
6%
760
19%
760
6%
2207
December1st to 10thNight
9%
760
4%
2660
2%
760
12%
760
4%
2352
December11th to 20thNight
12%
760
7%
3265
3%
759
17%
759
4%
2736
December21st to endNight
8%
827
3%
4847
1%
817
11%
817
2%
4118

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
18%12%5%8%6%35%45%6%27%
74902
Night
17%14%6%9%7%35%445%26%
75223
TransparencyDay
58%6%9%16%9%1
74607
Night
60%6%9%15%8%1
75052
SeeingDay
28%18%28%16%8%2
13562
Night
27%18%26%21%8%1
22768

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
13%20%9%15%10%45%34413%
1517
11th to 20thDay
14%19%7%13%11%35%43317%
1520
21st to endDay
11%16%9%13%9%5%6%5%4416%
1704
February1st to 10thDay
13%18%9%16%9%5%5%43414%
1620
11th to 20thDay
11%16%8%16%10%5%5%345%17%
1658
21st to endDay
15%18%8%14%8%5%433318%
1480
March1st to 10thDay
14%14%9%13%9%35%33423%
1797
11th to 20thDay
15%17%7%9%7%35%44425%
1908
21st to endDay
19%14%6%9%6%2333430%
2344
April1st to 10thDay
20%16%6%7%5%2444428%
2160
11th to 20thDay
20%13%47%433345%34%
2134
21st to endDay
25%13%47%433345%28%
2243
May1st to 10thDay
22%11%36%6%24446%31%
2483
11th to 20thDay
19%9%35%5%35%45%6%35%
2478
21st to endDay
18%9%27%6%35%5%6%7%32%
2725
June1st to 10thDay
25%7%36%6%45%5%6%7%27%
2520
11th to 20thDay
21%7%35%5%35%5%5%9%32%
2520
21st to endDay
22%7%47%7%35%6%5%6%28%
2520
July1st to 10thDay
15%6%36%6%36%5%5%8%36%
2520
11th to 20thDay
17%7%36%6%36%6%6%8%32%
2520
21st to endDay
17%6%36%6%36%7%6%9%30%
2744
August1st to 10thDay
16%7%36%6%35%7%6%8%33%
2506
11th to 20thDay
16%8%36%6%46%5%7%9%33%
2201
21st to endDay
16%7%26%6%46%5%7%7%33%
2376
September1st to 10thDay
17%7%35%6%35%46%8%37%
2160
11th to 20thDay
18%7%2442445%8%42%
2109
21st to endDay
19%8%25%5%35%5%5%7%35%
1980
October1st to 10thDay
26%10%37%5%34445%29%
1826
11th to 20thDay
21%14%46%6%35%5%5%5%27%
1800
21st to endDay
26%19%5%5%5%24445%21%
1796
November1st to 10thDay
15%16%5%8%7%445%46%27%
1671
11th to 20thDay
16%17%7%9%7%45%44424%
1644
21st to endDay
16%21%7%11%8%34435%19%
1520
December1st to 10thDay
19%23%11%12%8%3443411%
1520
11th to 20thDay
17%17%10%14%7%3444415%
1906
21st to endDay
20%19%8%11%9%3444414%
2772
January1st to 10thNight
14%20%9%15%10%35%43311%
2649
11th to 20thNight
13%19%8%14%10%46%43314%
2660
21st to endNight
10%17%9%14%9%47%5%4417%
2878
February1st to 10thNight
14%17%9%16%11%4444413%
2340
11th to 20thNight
12%15%8%15%10%6%5%44417%
2187
21st to endNight
14%17%7%12%10%45%44319%
1776
March1st to 10thNight
14%16%8%9%9%4433425%
2150
11th to 20thNight
13%18%7%9%8%3434427%
2047
21st to endNight
17%16%5%7%5%3433432%
2012
April1st to 10thNight
19%17%6%8%43344429%
1800
11th to 20thNight
21%14%46%5%44445%29%
1775
21st to endNight
20%12%5%6%6%34346%31%
1715
May1st to 10thNight
23%11%36%6%35%345%30%
1493
11th to 20thNight
15%9%36%5%26%46%8%36%
1415
21st to endNight
15%6%25%7%35%5%6%8%37%
1550
June1st to 10thNight
23%7%245%46%5%6%6%32%
1440
11th to 20thNight
20%6%26%43345%8%38%
1440
21st to endNight
21%7%35%6%4436%8%34%
1440
July1st to 10thNight
13%5%245%346%5%7%44%
1440
11th to 20thNight
12%5%35%5%36%5%6%9%41%
1440
21st to endNight
15%5%26%5%35%46%9%40%
1574
August1st to 10thNight
15%5%25%4345%7%8%42%
1432
11th to 20thNight
16%6%26%5%35%5%5%7%39%
1678
21st to endNight
14%7%36%5%35%45%8%39%
1980
September1st to 10thNight
16%7%25%5%35%5%5%7%40%
1800
11th to 20thNight
16%7%2443345%7%46%
1850
21st to endNight
20%7%25%43446%6%40%
1980
October1st to 10thNight
24%10%25%5%345%5%6%29%
2132
11th to 20thNight
20%12%37%6%35%5%46%29%
2160
21st to endNight
26%18%46%6%3434421%
2560
November1st to 10thNight
17%16%6%7%5%35%445%28%
2407
11th to 20thNight
17%16%7%8%6%34445%25%
2531
21st to endNight
17%20%9%11%6%34445%19%
2660
December1st to 10thNight
17%24%11%13%7%3433311%
2660
11th to 20thNight
17%19%9%12%7%35%43417%
3288
21st to endNight
24%17%7%15%6%3434412%
4884

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
76%5%5%11%3
1518
11th to 20thDay
72%45%10%7%2
1520
21st to endDay
72%47%9%6%2
1704
February1st to 10thDay
76%4410%32
1620
11th to 20thDay
72%47%9%8%1
1667
21st to endDay
72%46%9%8%1
1480
March1st to 10thDay
68%38%12%8%2
1800
11th to 20thDay
64%5%9%10%10%3
1908
21st to endDay
60%36%14%14%3
2344
April1st to 10thDay
59%48%17%10%2
2160
11th to 20thDay
54%5%8%18%13%2
2134
21st to endDay
59%5%8%13%11%3
2243
May1st to 10thDay
56%5%9%18%11%2
2483
11th to 20thDay
49%7%9%21%12%1
2482
21st to endDay
50%10%11%18%10%1
2725
June1st to 10thDay
56%7%11%15%10%1
2520
11th to 20thDay
50%7%11%22%8%1
2520
21st to endDay
55%8%11%17%8%1
2520
July1st to 10thDay
45%9%11%24%11%
2450
11th to 20thDay
48%9%13%24%6%
2445
21st to endDay
48%10%13%19%9%
2591
August1st to 10thDay
48%11%13%20%8%
2492
11th to 20thDay
47%9%15%21%8%
2201
21st to endDay
47%10%11%22%9%
2376
September1st to 10thDay
45%7%11%25%11%1
2160
11th to 20thDay
41%5%10%28%15%1
2109
21st to endDay
48%8%12%22%10%1
1980
October1st to 10thDay
58%6%9%16%11%
1826
11th to 20thDay
58%7%13%15%7%1
1800
21st to endDay
67%5%9%11%7%1
1796
November1st to 10thDay
60%7%10%15%8%
1671
11th to 20thDay
64%5%9%12%7%3
1644
21st to endDay
69%5%10%10%4
1520
December1st to 10thDay
79%47%7%21
1520
11th to 20thDay
73%6%7%9%5%
1906
21st to endDay
74%5%5%6%9%
2772
January1st to 10thNight
79%46%7%4
2649
11th to 20thNight
77%5%5%8%41
2660
21st to endNight
71%5%6%10%7%2
2878
February1st to 10thNight
76%5%7%6%5%1
2340
11th to 20thNight
71%5%5%11%7%
2189
21st to endNight
70%5%6%11%7%1
1776
March1st to 10thNight
65%49%13%8%1
2160
11th to 20thNight
63%5%7%15%8%2
2048
21st to endNight
57%46%16%14%3
2012
April1st to 10thNight
60%48%16%9%2
1800
11th to 20thNight
57%5%9%16%12%
1775
21st to endNight
56%6%8%16%11%3
1715
May1st to 10thNight
57%5%9%13%14%2
1493
11th to 20thNight
47%6%10%21%14%2
1416
21st to endNight
45%9%15%19%12%1
1551
June1st to 10thNight
51%8%13%19%8%1
1440
11th to 20thNight
47%5%14%21%12%1
1440
21st to endNight
49%8%13%21%9%
1440
July1st to 10thNight
38%8%14%26%13%1
1400
11th to 20thNight
39%9%15%28%8%
1392
21st to endNight
41%9%15%24%10%1
1486
August1st to 10thNight
39%9%17%26%8%
1422
11th to 20thNight
44%10%13%23%10%
1678
21st to endNight
42%9%14%26%9%
1980
September1st to 10thNight
43%8%13%26%10%1
1800
11th to 20thNight
39%6%12%31%11%
1850
21st to endNight
44%8%10%25%11%1
1980
October1st to 10thNight
54%8%10%17%10%1
2132
11th to 20thNight
56%9%13%15%6%1
2160
21st to endNight
67%6%9%10%6%1
2560
November1st to 10thNight
59%6%12%13%8%2
2407
11th to 20thNight
63%6%8%13%7%3
2531
21st to endNight
70%6%8%11%41
2660
December1st to 10thNight
80%47%7%3
2660
11th to 20thNight
73%5%7%10%5%
3288
21st to endNight
77%5%6%8%5%
4884

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
27%22%33%12%5%1
180
11th to 20thDay
31%26%33%8%21
180
21st to endDay
23%28%34%12%3
215
February1st to 10thDay
41%33%23%4
240
11th to 20thDay
35%27%31%6%1
325
21st to endDay
34%25%27%9%4
346
March1st to 10thDay
31%21%30%14%3
420
11th to 20thDay
32%23%30%11%31
420
21st to endDay
34%26%20%12%7%1
462
April1st to 10thDay
35%21%26%11%6%1
420
11th to 20thDay
36%17%22%15%7%2
412
21st to endDay
37%18%28%9%6%2
420
May1st to 10thDay
33%18%29%10%7%3
423
11th to 20thDay
26%18%28%20%6%1
447
21st to endDay
23%18%29%18%10%1
485
June1st to 10thDay
31%16%28%19%42
450
11th to 20thDay
24%15%30%20%8%3
450
21st to endDay
28%16%30%19%6%2
450
July1st to 10thDay
18%11%31%26%12%2
445
11th to 20thDay
16%11%36%24%10%2
444
21st to endDay
17%14%37%24%7%2
488
August1st to 10thDay
17%12%30%23%15%4
446
11th to 20thDay
19%10%28%24%13%6%
439
21st to endDay
15%17%28%23%12%5%
495
September1st to 10thDay
22%10%29%18%14%7%
450
11th to 20thDay
20%13%22%18%17%9%
450
21st to endDay
20%15%27%21%14%4
450
October1st to 10thDay
31%16%21%14%13%5%
450
11th to 20thDay
31%20%24%18%6%1
450
21st to endDay
38%18%23%16%4
403
November1st to 10thDay
35%14%27%16%8%1
365
11th to 20thDay
37%23%26%8%6%1
304
21st to endDay
33%23%32%11%1
180
December1st to 10thDay
39%16%31%12%21
180
11th to 20thDay
33%27%33%5%11
180
21st to endDay
37%20%34%6%21
198
January1st to 10thNight
29%25%30%13%3
760
11th to 20thNight
31%24%30%12%3
760
21st to endNight
21%25%32%18%4
835
February1st to 10thNight
29%26%30%13%1
720
11th to 20thNight
27%25%32%14%2
703
21st to endNight
27%23%32%15%3
592
March1st to 10thNight
28%23%30%18%2
720
11th to 20thNight
30%23%28%15%31
720
21st to endNight
27%21%26%18%5%1
792
April1st to 10thNight
32%19%28%18%3
720
11th to 20thNight
32%20%23%19%6%
711
21st to endNight
32%17%24%20%7%
635
May1st to 10thNight
31%12%26%22%9%1
413
11th to 20thNight
19%11%31%31%7%1
354
21st to endNight
17%13%28%29%13%
389
June1st to 10thNight
27%9%26%27%11%1
360
11th to 20thNight
23%6%25%33%13%
360
21st to endNight
21%10%28%32%9%
360
July1st to 10thNight
11%5%29%38%16%
350
11th to 20thNight
11%5%28%37%18%1
348
21st to endNight
15%6%26%40%12%1
394
August1st to 10thNight
17%7%22%37%16%1
358
11th to 20thNight
20%7%21%31%21%2
614
21st to endNight
19%7%24%33%17%1
792
September1st to 10thNight
19%11%24%28%16%2
720
11th to 20thNight
21%8%20%29%20%3
720
21st to endNight
25%11%23%21%19%2
720
October1st to 10thNight
31%14%21%18%14%2
720
11th to 20thNight
30%15%25%23%7%1
720
21st to endNight
37%18%22%19%3
792
November1st to 10thNight
32%15%28%18%7%
740
11th to 20thNight
31%21%27%13%8%1
760
21st to endNight
32%23%25%15%5%
760
December1st to 10thNight
33%26%24%14%3
760
11th to 20thNight
30%25%27%14%31
760
21st to endNight
33%26%27%12%2
836
Page generated at 2024-01-28 05:26:35. Version ac07

Copyright 2024 Attilla Danko


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