Skunk Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Skunk Ridge Observatory clear sky chart from 2005-11-06 to 2024-01-17.

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
38%
24047
12%
74429
8%
23987
42%
23987
12%
58354

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
20%
950
7%
2648
3%
946
24%
946
7%
2285
January11th to 20thNight
14%
839
7%
2521
3%
839
18%
839
6%
2182
January21st to endNight
17%
792
8%
2574
3%
792
24%
792
7%
2138
February1st to 10thNight
19%
720
7%
2196
3%
720
22%
720
7%
1849
February11th to 20thNight
16%
702
10%
2099
5%
700
21%
700
8%
1715
February21st to endNight
13%
592
9%
1776
3%
592
18%
592
8%
1485
March1st to 10thNight
21%
720
13%
2160
6%
720
26%
720
10%
1667
March11th to 20thNight
23%
720
10%
1992
6%
720
26%
720
10%
1630
March21st to endNight
27%
792
9%
2178
5%
792
31%
792
11%
1792
April1st to 10thNight
30%
555
13%
1815
8%
555
38%
555
13%
1364
April11th to 20thNight
33%
533
16%
1758
9%
533
42%
533
12%
1314
April21st to endNight
29%
540
12%
1620
5%
540
35%
540
12%
1283
May1st to 10thNight
32%
540
9%
1620
4%
540
36%
540
11%
1329
May11th to 20thNight
42%
531
12%
1593
8%
531
45%
531
12%
1280
May21st to endNight
55%
583
12%
1745
10%
582
58%
582
16%
1313
June1st to 10thNight
59%
540
13%
1588
10%
540
62%
540
19%
1158
June11th to 20thNight
61%
540
16%
1440
11%
540
65%
540
21%
1061
June21st to endNight
59%
540
14%
1440
9%
540
62%
540
19%
1068
July1st to 10thNight
62%
525
12%
1400
10%
525
63%
525
17%
1090
July11th to 20thNight
69%
522
13%
1443
10%
522
71%
522
19%
1071
July21st to endNight
65%
591
14%
1672
11%
558
67%
558
18%
1243
August1st to 10thNight
69%
537
16%
1600
15%
534
70%
534
20%
1150
August11th to 20thNight
68%
534
17%
1631
15%
534
71%
534
20%
1171
August21st to endNight
71%
594
16%
1980
18%
594
72%
594
19%
1378
September1st to 10thNight
62%
612
15%
1872
13%
612
65%
612
17%
1375
September11th to 20thNight
62%
720
21%
1980
15%
720
66%
720
21%
1444
September21st to endNight
51%
720
15%
1980
10%
720
55%
720
17%
1494
October1st to 10thNight
56%
720
19%
1980
13%
720
60%
720
21%
1415
October11th to 20thNight
41%
720
15%
2099
9%
720
47%
720
14%
1622
October21st to endNight
31%
792
14%
2538
10%
792
38%
792
11%
1968
November1st to 10thNight
40%
740
16%
2406
15%
740
45%
740
16%
1735
November11th to 20thNight
30%
760
17%
2470
10%
760
40%
760
11%
1913
November21st to endNight
32%
760
12%
2470
9%
760
37%
760
9%
1965
December1st to 10thNight
21%
760
8%
2470
4%
760
27%
760
8%
2038
December11th to 20thNight
23%
760
10%
2975
5%
759
28%
759
6%
2356
December21st to endNight
16%
951
3%
4700
2%
935
21%
935
3%
4013

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
15%8%36%5%35%5%5%7%38%
75107
Night
15%8%36%5%3445%7%39%
74719
TransparencyDay
30%38%7%14%9%2
74820
Night
30%38%7%14%10%2
74526
SeeingDay
19%13%27%22%12%5%
14203
Night
19%11%26%27%15%2
24052

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
17%13%6%8%434435%32%
1517
11th to 20thDay
20%13%6%8%6%34445%27%
1577
21st to endDay
17%13%6%8%6%34445%30%
1782
February1st to 10thDay
21%13%5%7%5%3335%5%31%
1760
11th to 20thDay
18%11%5%7%5%45%35%6%32%
1748
21st to endDay
19%13%5%8%43435%6%31%
1480
March1st to 10thDay
19%8%46%5%4444438%
1800
11th to 20thDay
19%11%37%5%3445%7%33%
1967
21st to endDay
21%11%46%5%35%446%31%
2178
April1st to 10thDay
15%8%36%5%345%6%8%37%
2160
11th to 20thDay
17%8%35%5%35%35%7%40%
2148
21st to endDay
19%7%36%5%35%5%48%36%
2340
May1st to 10thDay
21%7%36%6%44447%35%
2340
11th to 20thDay
20%8%36%5%35%447%35%
2301
21st to endDay
10%5%26%7%47%7%7%10%35%
2531
June1st to 10thDay
12%6%25%6%445%5%8%43%
2366
11th to 20thDay
9%436%6%446%6%10%43%
2520
21st to endDay
9%5%35%6%46%5%6%9%41%
2520
July1st to 10thDay
13%6%26%5%36%6%6%9%39%
2520
11th to 20thDay
9%5%25%6%46%6%8%10%40%
2466
21st to endDay
11%5%25%6%45%6%6%7%42%
2547
August1st to 10thDay
8%5%25%6%36%6%7%9%43%
2327
11th to 20thDay
11%5%26%5%36%6%7%10%40%
2266
21st to endDay
8%5%25%5%35%5%6%8%47%
2376
September1st to 10thDay
14%5%25%5%345%5%7%46%
2070
11th to 20thDay
9%5%26%5%35%5%6%7%47%
1980
21st to endDay
15%425%434347%51%
1980
October1st to 10thDay
11%5%25%5%35%346%51%
1980
11th to 20thDay
14%6%35%43445%6%46%
1860
21st to endDay
21%8%345%34446%38%
1816
November1st to 10thDay
9%6%34423436%55%
1672
11th to 20thDay
16%10%45%5%34446%39%
1710
21st to endDay
19%9%36%434346%40%
1710
December1st to 10thDay
22%12%5%7%7%34345%28%
1710
11th to 20thDay
16%14%5%7%5%35%445%31%
2153
21st to endDay
21%20%47%6%34445%21%
2929
January1st to 10thNight
18%11%5%9%7%35%44429%
2648
11th to 20thNight
21%15%6%9%6%33335%27%
2521
21st to endNight
17%14%5%7%6%34445%30%
2574
February1st to 10thNight
23%13%6%7%5%44435%27%
2196
11th to 20thNight
18%10%5%7%6%3445%6%32%
2098
21st to endNight
22%13%47%5%23445%29%
1776
March1st to 10thNight
18%9%46%6%34345%38%
2160
11th to 20thNight
19%8%45%43445%6%37%
1992
21st to endNight
19%9%46%5%3445%7%34%
2178
April1st to 10thNight
14%7%35%5%26%5%7%8%39%
1815
11th to 20thNight
15%8%36%5%3345%6%41%
1758
21st to endNight
18%6%36%6%3436%7%37%
1620
May1st to 10thNight
17%9%36%5%35%5%5%7%34%
1620
11th to 20thNight
15%6%36%5%46%5%6%8%38%
1592
21st to endNight
9%425%445%6%7%12%42%
1744
June1st to 10thNight
9%5%245%345%5%9%50%
1588
11th to 20thNight
7%5%25%345%46%11%48%
1440
21st to endNight
7%4145%35%6%7%10%48%
1440
July1st to 10thNight
11%5%25%6%35%5%6%9%44%
1440
11th to 20thNight
6%4244346%6%10%51%
1491
21st to endNight
10%425%5%345%5%8%49%
1771
August1st to 10thNight
8%4245%35%6%6%10%47%
1611
11th to 20thNight
8%325%5%35%6%6%9%48%
1631
21st to endNight
7%32443445%10%54%
1980
September1st to 10thNight
12%42442346%8%51%
1872
11th to 20thNight
10%42342445%9%53%
1980
21st to endNight
13%425%5%2335%6%52%
1980
October1st to 10thNight
9%4245%2445%6%55%
1980
11th to 20thNight
15%6%244345%6%7%45%
2099
21st to endNight
19%7%36%433446%40%
2538
November1st to 10thNight
13%7%2442445%5%50%
2406
11th to 20thNight
16%7%46%43445%7%41%
2470
21st to endNight
19%10%45%434346%37%
2470
December1st to 10thNight
21%11%47%5%3445%5%31%
2470
11th to 20thNight
19%12%5%7%5%34446%33%
3042
21st to endNight
21%20%5%8%7%44445%19%
4728

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
36%40%8%10%6%
1518
11th to 20thDay
38%41%5%10%6%
1577
21st to endDay
39%37%7%14%21
1782
February1st to 10thDay
37%35%5%15%6%1
1760
11th to 20thDay
36%37%8%12%6%1
1758
21st to endDay
39%36%6%13%5%1
1480
March1st to 10thDay
31%37%7%17%8%
1800
11th to 20thDay
36%37%7%11%7%2
1967
21st to endDay
39%37%7%13%41
2178
April1st to 10thDay
27%38%7%16%11%1
2160
11th to 20thDay
31%35%6%14%11%2
2148
21st to endDay
33%37%6%15%7%1
2340
May1st to 10thDay
35%38%6%14%6%1
2340
11th to 20thDay
33%38%7%11%10%1
2305
21st to endDay
26%40%11%13%9%1
2531
June1st to 10thDay
26%38%7%17%10%1
2366
11th to 20thDay
22%38%10%15%13%1
2520
21st to endDay
25%38%10%14%9%4
2520
July1st to 10thDay
26%41%8%12%11%2
2451
11th to 20thDay
25%41%9%13%11%2
2391
21st to endDay
25%40%10%15%8%2
2405
August1st to 10thDay
22%40%9%16%11%1
2314
11th to 20thDay
24%37%9%18%12%1
2266
21st to endDay
21%40%7%15%11%6%
2376
September1st to 10thDay
26%37%7%14%11%4
2070
11th to 20thDay
22%38%7%16%15%3
1980
21st to endDay
25%38%6%14%16%2
1980
October1st to 10thDay
21%37%7%14%19%2
1980
11th to 20thDay
26%37%7%18%11%1
1860
21st to endDay
32%38%6%14%9%1
1816
November1st to 10thDay
16%40%6%19%16%3
1672
11th to 20thDay
30%40%5%13%10%2
1710
21st to endDay
29%39%5%14%12%1
1710
December1st to 10thDay
38%39%7%12%4
1710
11th to 20thDay
38%33%6%12%10%
2150
21st to endDay
54%27%6%8%5%
2929
January1st to 10thNight
37%41%6%12%4
2648
11th to 20thNight
39%41%6%9%5%
2521
21st to endNight
39%37%7%13%41
2574
February1st to 10thNight
40%36%7%12%4
2196
11th to 20thNight
36%37%6%13%7%1
2099
21st to endNight
39%36%7%10%5%2
1776
March1st to 10thNight
31%36%5%16%11%1
2160
11th to 20thNight
33%38%8%13%6%1
1992
21st to endNight
34%37%8%15%5%1
2178
April1st to 10thNight
25%39%8%17%10%2
1815
11th to 20thNight
28%36%7%12%13%5%
1758
21st to endNight
31%38%7%13%9%2
1620
May1st to 10thNight
34%38%7%13%6%1
1620
11th to 20thNight
31%39%7%10%12%2
1593
21st to endNight
22%41%10%14%10%3
1745
June1st to 10thNight
20%38%10%16%13%2
1588
11th to 20thNight
19%39%10%17%13%3
1440
21st to endNight
20%39%11%14%12%5%
1440
July1st to 10thNight
25%39%9%12%11%4
1400
11th to 20thNight
20%40%9%16%13%3
1443
21st to endNight
21%40%9%20%10%1
1672
August1st to 10thNight
19%39%10%18%12%2
1600
11th to 20thNight
19%39%9%19%13%1
1631
21st to endNight
17%39%9%17%13%5%
1980
September1st to 10thNight
23%38%8%14%12%5%
1872
11th to 20thNight
19%38%7%16%17%3
1980
21st to endNight
25%37%5%14%17%3
1980
October1st to 10thNight
19%37%6%16%19%3
1980
11th to 20thNight
27%38%6%15%12%2
2099
21st to endNight
30%37%6%14%11%2
2538
November1st to 10thNight
19%41%5%15%17%3
2406
11th to 20thNight
28%40%6%12%12%2
2470
21st to endNight
31%40%5%13%10%1
2470
December1st to 10thNight
35%40%7%13%5%
2470
11th to 20thNight
38%34%6%14%8%
3044
21st to endNight
54%27%7%8%4
4728

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
26%25%32%13%31
270
11th to 20thDay
31%27%29%11%2
258
21st to endDay
28%30%34%6%2
264
February1st to 10thDay
32%28%29%8%2
240
11th to 20thDay
35%28%29%8%
240
21st to endDay
34%22%35%7%2
198
March1st to 10thDay
25%30%35%9%1
240
11th to 20thDay
27%23%32%12%6%
407
21st to endDay
32%21%28%13%6%
462
April1st to 10thDay
24%18%30%17%9%1
420
11th to 20thDay
26%18%27%20%6%3
412
21st to endDay
25%19%34%14%6%2
420
May1st to 10thDay
23%19%35%13%6%4
423
11th to 20thDay
20%14%30%23%9%5%
447
21st to endDay
14%9%28%25%15%8%
485
June1st to 10thDay
13%7%26%29%17%7%
476
11th to 20thDay
11%8%27%33%15%7%
630
21st to endDay
11%7%30%28%17%8%
630
July1st to 10thDay
14%5%18%27%20%16%
621
11th to 20thDay
9%5%24%29%23%10%
564
21st to endDay
14%320%32%19%12%
488
August1st to 10thDay
9%420%31%22%13%
446
11th to 20thDay
13%5%21%32%19%10%
439
21st to endDay
10%418%31%26%10%
495
September1st to 10thDay
13%6%19%29%25%8%
450
11th to 20thDay
11%417%32%23%13%
450
21st to endDay
18%8%23%24%20%7%
450
October1st to 10thDay
12%6%26%33%17%5%
450
11th to 20thDay
20%15%32%20%11%2
450
21st to endDay
24%18%37%18%3
331
November1st to 10thDay
13%19%34%26%6%3
270
11th to 20thDay
26%21%26%22%41
270
21st to endDay
27%16%35%17%4
270
December1st to 10thDay
26%23%34%12%5%1
270
11th to 20thDay
22%25%33%14%6%
270
21st to endDay
33%23%30%10%3
297
January1st to 10thNight
24%20%31%20%5%
950
11th to 20thNight
31%18%32%16%3
839
21st to endNight
25%19%34%18%3
792
February1st to 10thNight
29%17%30%22%2
720
11th to 20thNight
26%22%32%19%1
703
21st to endNight
31%16%35%17%1
592
March1st to 10thNight
24%20%31%22%4
720
11th to 20thNight
24%17%33%20%7%1
720
21st to endNight
24%15%30%24%6%
792
April1st to 10thNight
18%13%35%26%7%
555
11th to 20thNight
20%14%29%26%11%1
533
21st to endNight
21%11%35%25%8%1
540
May1st to 10thNight
21%9%33%24%12%1
540
11th to 20thNight
17%6%29%31%16%2
531
21st to endNight
11%422%32%27%4
584
June1st to 10thNight
11%321%40%23%2
540
11th to 20thNight
9%419%41%24%3
540
21st to endNight
7%423%36%27%3
540
July1st to 10thNight
13%213%32%30%10%
525
11th to 20thNight
6%314%37%34%5%
522
21st to endNight
13%213%37%31%4
591
August1st to 10thNight
10%210%37%36%5%
537
11th to 20thNight
9%213%37%34%6%
534
21st to endNight
7%314%33%38%6%
594
September1st to 10thNight
14%215%33%31%5%
612
11th to 20thNight
9%417%30%34%5%
720
21st to endNight
14%7%22%31%24%3
720
October1st to 10thNight
11%6%24%33%22%5%
720
11th to 20thNight
19%10%26%28%15%1
720
21st to endNight
23%13%30%23%10%1
792
November1st to 10thNight
16%11%29%26%16%1
740
11th to 20thNight
20%18%29%23%10%1
760
21st to endNight
26%14%23%28%7%1
760
December1st to 10thNight
28%16%30%20%6%
760
11th to 20thNight
25%17%29%21%6%1
760
21st to endNight
30%16%32%19%3
954
Page generated at 2024-01-14 09:55:02. Version ac07

Copyright 2024 Attilla Danko


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