Mossy Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mossy Creek Observatory clear sky chart from 2005-11-06 to 2024-01-13.

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
49%
23884
20%
74502
16%
23832
54%
23832
24%
48526

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
33%
760
18%
2459
13%
757
42%
757
18%
1681
January11th to 20thNight
28%
732
17%
2378
11%
732
36%
732
15%
1717
January21st to endNight
28%
792
22%
2574
13%
792
40%
792
20%
1721
February1st to 10thNight
34%
720
19%
2210
13%
720
42%
720
20%
1531
February11th to 20thNight
23%
703
17%
2099
9%
700
31%
700
18%
1499
February21st to endNight
26%
592
21%
1776
11%
592
35%
592
18%
1272
March1st to 10thNight
36%
720
23%
2080
14%
720
43%
720
25%
1368
March11th to 20thNight
34%
720
18%
1980
11%
720
38%
720
23%
1384
March21st to endNight
39%
792
18%
2178
12%
792
43%
792
24%
1489
April1st to 10thNight
43%
716
21%
1976
13%
716
50%
716
32%
1221
April11th to 20thNight
45%
533
25%
1727
18%
533
54%
533
27%
1055
April21st to endNight
52%
540
25%
1620
19%
540
57%
540
28%
1033
May1st to 10thNight
51%
540
17%
1620
10%
540
54%
540
27%
1035
May11th to 20thNight
53%
531
15%
1593
11%
531
55%
531
25%
1055
May21st to endNight
63%
582
17%
1744
13%
582
65%
582
27%
1127
June1st to 10thNight
63%
540
16%
1620
13%
540
64%
540
28%
1031
June11th to 20thNight
70%
540
15%
1620
12%
540
73%
540
32%
973
June21st to endNight
66%
540
17%
1620
15%
540
68%
540
27%
1039
July1st to 10thNight
66%
525
12%
1575
11%
525
66%
525
23%
1074
July11th to 20thNight
73%
522
15%
1566
13%
522
74%
522
31%
988
July21st to endNight
67%
591
16%
1672
15%
558
69%
558
26%
1117
August1st to 10thNight
68%
537
16%
1600
14%
534
68%
534
28%
1030
August11th to 20thNight
65%
534
18%
1598
17%
534
65%
534
25%
1056
August21st to endNight
69%
594
19%
1967
20%
594
70%
594
26%
1224
September1st to 10thNight
64%
710
22%
1970
20%
710
65%
710
30%
1273
September11th to 20thNight
60%
720
21%
1980
19%
720
61%
720
28%
1323
September21st to endNight
60%
720
28%
1980
23%
720
65%
720
33%
1246
October1st to 10thNight
58%
720
28%
1980
27%
720
60%
720
36%
1202
October11th to 20thNight
54%
720
28%
2146
26%
720
60%
720
33%
1283
October21st to endNight
52%
792
31%
2376
27%
792
60%
792
32%
1424
November1st to 10thNight
56%
740
27%
2389
27%
740
62%
740
30%
1390
November11th to 20thNight
48%
760
27%
2470
23%
760
56%
760
28%
1472
November21st to endNight
47%
760
26%
2470
21%
760
56%
760
28%
1496
December1st to 10thNight
35%
760
18%
2470
14%
760
41%
760
17%
1726
December11th to 20thNight
39%
759
22%
2974
17%
759
47%
759
17%
1964
December21st to endNight
33%
827
12%
4445
12%
817
41%
817
10%
3007

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
13%7%36%6%45%5%6%8%38%
74888
Night
14%7%36%5%35%5%6%7%39%
74864
TransparencyDay
44%411%22%16%3
74611
Night
44%410%22%17%3
74660
SeeingDay
17%8%19%24%21%11%
13779
Night
17%6%19%34%21%3
23896

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
18%7%48%7%45%6%5%6%32%
1706
11th to 20thDay
18%10%5%10%7%34435%32%
1638
21st to endDay
17%9%345%2446%7%39%
1782
February1st to 10thDay
19%10%46%6%3445%5%33%
1746
11th to 20thDay
22%9%48%5%3345%6%32%
1748
21st to endDay
22%9%37%5%34446%34%
1480
March1st to 10thDay
16%8%345%345%5%7%41%
1879
11th to 20thDay
18%8%45%6%35%5%6%7%33%
1980
21st to endDay
16%10%46%5%45%446%35%
2178
April1st to 10thDay
12%5%36%445%6%5%8%43%
1998
11th to 20thDay
15%7%35%435%447%43%
2181
21st to endDay
13%6%36%6%35%46%7%41%
2340
May1st to 10thDay
12%6%35%6%45%5%6%8%41%
2340
11th to 20thDay
13%6%36%7%46%6%6%7%35%
2301
21st to endDay
11%6%26%6%45%6%6%10%38%
2531
June1st to 10thDay
9%5%36%7%46%7%6%9%38%
2340
11th to 20thDay
5%436%7%5%7%7%8%9%39%
2340
21st to endDay
8%5%25%5%5%7%6%8%11%37%
2340
July1st to 10thDay
9%6%36%8%5%6%7%8%10%31%
2340
11th to 20thDay
11%5%36%6%46%6%8%10%34%
2340
21st to endDay
9%6%36%8%5%7%7%9%9%29%
2547
August1st to 10thDay
10%6%37%7%5%7%7%8%10%31%
2327
11th to 20thDay
10%6%37%7%46%7%8%10%32%
2303
21st to endDay
10%6%36%6%47%7%8%9%35%
2376
September1st to 10thDay
10%5%26%7%36%5%5%8%43%
1980
11th to 20thDay
13%5%36%5%445%6%7%42%
1980
21st to endDay
13%5%35%5%2445%7%47%
1980
October1st to 10thDay
11%6%2442345%6%53%
1980
11th to 20thDay
13%5%25%424436%51%
1814
21st to endDay
15%6%34434446%48%
1980
November1st to 10thDay
11%5%15%324347%54%
1686
11th to 20thDay
12%6%24434347%48%
1710
21st to endDay
15%7%35%42445%6%44%
1710
December1st to 10thDay
19%11%47%5%35%445%34%
1710
11th to 20thDay
14%11%46%5%346%6%7%34%
2153
21st to endDay
16%12%37%6%36%45%7%30%
3124
January1st to 10thNight
18%9%48%5%345%36%35%
2459
11th to 20thNight
20%11%47%5%35%45%6%30%
2378
21st to endNight
16%9%46%6%34445%38%
2574
February1st to 10thNight
18%8%47%5%345%5%7%34%
2210
11th to 20thNight
22%9%37%5%35%45%5%34%
2098
21st to endNight
22%10%46%5%345%46%32%
1776
March1st to 10thNight
16%8%36%5%34347%40%
2080
11th to 20thNight
17%8%47%6%25%5%5%6%36%
1980
21st to endNight
16%7%36%5%35%5%6%6%38%
2178
April1st to 10thNight
12%5%35%5%45%5%6%8%44%
1976
11th to 20thNight
14%6%35%4245%5%7%44%
1727
21st to endNight
14%6%35%6%35%45%6%43%
1620
May1st to 10thNight
13%5%35%6%35%6%6%10%38%
1620
11th to 20thNight
14%6%46%5%345%8%9%36%
1592
21st to endNight
7%5%47%6%46%6%7%12%37%
1744
June1st to 10thNight
8%6%35%7%36%6%8%12%36%
1620
11th to 20thNight
4435%6%45%6%8%13%42%
1620
21st to endNight
6%6%36%7%46%7%6%9%39%
1620
July1st to 10thNight
11%5%37%7%5%7%6%8%9%33%
1620
11th to 20thNight
6%5%36%447%6%9%12%38%
1620
21st to endNight
7%5%46%8%46%7%9%12%32%
1771
August1st to 10thNight
8%5%26%7%46%7%8%10%38%
1611
11th to 20thNight
9%8%35%6%47%5%8%9%37%
1598
21st to endNight
10%5%36%5%45%7%7%10%38%
1967
September1st to 10thNight
11%6%26%6%445%5%6%44%
1970
11th to 20thNight
11%7%37%7%35%46%8%39%
1980
21st to endNight
11%5%25%5%35%5%47%47%
1980
October1st to 10thNight
13%5%25%423346%51%
1980
11th to 20thNight
15%6%3443335%6%49%
2146
21st to endNight
14%6%35%42335%5%50%
2376
November1st to 10thNight
14%5%245%24446%50%
2389
11th to 20thNight
14%7%35%43445%6%46%
2470
21st to endNight
15%7%35%5%24447%45%
2470
December1st to 10thNight
19%10%37%7%34446%32%
2470
11th to 20thNight
16%9%38%5%44446%37%
3042
21st to endNight
16%12%48%6%36%6%7%8%25%
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
53%47%21%12%3
1707
11th to 20thDay
56%37%19%13%2
1638
21st to endDay
45%39%24%18%1
1782
February1st to 10thDay
54%37%19%16%2
1746
11th to 20thDay
55%38%19%13%2
1758
21st to endDay
53%38%15%17%6%
1480
March1st to 10thDay
44%37%22%19%4
1879
11th to 20thDay
50%311%17%15%4
1980
21st to endDay
51%39%22%13%2
2178
April1st to 10thDay
39%410%25%19%3
1998
11th to 20thDay
42%37%20%24%6%
2181
21st to endDay
42%39%27%15%3
2340
May1st to 10thDay
41%411%27%14%3
2340
11th to 20thDay
47%5%14%21%11%2
2305
21st to endDay
41%6%14%24%14%2
2531
June1st to 10thDay
42%5%15%23%13%2
2340
11th to 20thDay
38%6%18%21%15%2
2340
21st to endDay
38%7%14%22%14%4
2340
July1st to 10thDay
45%7%16%18%13%2
2275
11th to 20thDay
42%7%17%17%12%5%
2271
21st to endDay
45%7%16%21%10%1
2405
August1st to 10thDay
45%7%18%19%10%1
2314
11th to 20thDay
45%6%15%19%14%1
2303
21st to endDay
41%7%14%21%13%4
2376
September1st to 10thDay
40%5%12%22%16%6%
1980
11th to 20thDay
41%6%9%23%18%3
1980
21st to endDay
38%49%24%20%6%
1980
October1st to 10thDay
33%38%25%25%6%
1980
11th to 20thDay
36%28%25%24%5%
1814
21st to endDay
39%25%27%22%5%
1980
November1st to 10thDay
32%37%23%29%6%
1686
11th to 20thDay
38%26%24%25%5%
1710
21st to endDay
41%37%25%21%3
1710
December1st to 10thDay
52%48%22%11%2
1710
11th to 20thDay
48%39%20%17%2
2150
21st to endDay
55%27%26%10%1
3124
January1st to 10thNight
52%28%20%15%3
2459
11th to 20thNight
57%38%15%15%2
2378
21st to endNight
49%36%24%16%1
2574
February1st to 10thNight
50%48%21%15%1
2210
11th to 20thNight
54%37%19%13%4
2099
21st to endNight
54%37%17%14%4
1776
March1st to 10thNight
45%37%19%22%5%
2080
11th to 20thNight
48%48%21%15%3
1980
21st to endNight
47%39%25%14%2
2178
April1st to 10thNight
37%312%25%19%4
1976
11th to 20thNight
40%37%21%22%7%
1727
21st to endNight
41%49%28%15%2
1620
May1st to 10thNight
42%414%25%13%2
1620
11th to 20thNight
44%5%17%23%11%1
1593
21st to endNight
39%8%14%25%12%2
1745
June1st to 10thNight
38%7%16%22%15%1
1620
11th to 20thNight
31%9%20%23%15%2
1620
21st to endNight
40%7%14%22%13%5%
1620
July1st to 10thNight
45%8%15%18%12%2
1575
11th to 20thNight
36%7%22%18%13%5%
1566
21st to endNight
40%9%16%25%9%1
1672
August1st to 10thNight
39%7%18%25%10%1
1600
11th to 20thNight
42%8%16%18%15%1
1598
21st to endNight
39%6%16%25%13%2
1967
September1st to 10thNight
41%413%20%16%5%
1970
11th to 20thNight
43%5%11%20%20%2
1980
21st to endNight
38%38%23%23%5%
1980
October1st to 10thNight
36%38%21%26%7%
1980
11th to 20thNight
37%37%25%23%6%
2146
21st to endNight
37%2324%26%7%
2376
November1st to 10thNight
37%36%22%25%8%
2389
11th to 20thNight
39%35%23%24%6%
2470
21st to endNight
40%36%28%20%3
2470
December1st to 10thNight
54%38%21%12%2
2470
11th to 20thNight
50%26%21%18%2
3044
21st to endNight
57%28%19%13%1
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
23%17%32%22%41
270
11th to 20thDay
27%18%28%18%8%1
246
21st to endDay
23%19%35%17%6%
264
February1st to 10thDay
25%18%30%20%6%
240
11th to 20thDay
38%18%27%15%3
240
21st to endDay
35%22%25%15%3
198
March1st to 10thDay
23%14%31%23%9%
319
11th to 20thDay
25%15%29%25%5%1
420
21st to endDay
24%12%25%27%11%
462
April1st to 10thDay
18%13%24%26%18%1
420
11th to 20thDay
17%13%22%26%18%4
412
21st to endDay
20%9%24%27%15%6%
420
May1st to 10thDay
16%11%29%23%15%6%
423
11th to 20thDay
16%6%20%21%26%11%
447
21st to endDay
15%5%13%25%21%21%
485
June1st to 10thDay
12%213%27%29%17%
450
11th to 20thDay
6%416%26%28%20%
450
21st to endDay
10%418%23%28%17%
450
July1st to 10thDay
13%210%19%29%27%
445
11th to 20thDay
11%38%24%30%24%
444
21st to endDay
13%26%26%31%22%
488
August1st to 10thDay
16%49%20%28%23%
446
11th to 20thDay
14%28%26%31%20%
439
21st to endDay
15%25%18%30%30%
495
September1st to 10thDay
12%39%21%33%22%
450
11th to 20thDay
15%48%18%33%22%
450
21st to endDay
16%412%27%30%11%
450
October1st to 10thDay
16%315%27%26%14%
450
11th to 20thDay
14%8%21%28%24%5%
450
21st to endDay
21%6%19%29%22%3
495
November1st to 10thDay
17%7%24%26%20%6%
284
11th to 20thDay
14%14%29%27%16%1
270
21st to endDay
16%9%25%31%17%2
270
December1st to 10thDay
24%16%26%23%10%
270
11th to 20thDay
25%9%26%29%10%1
270
21st to endDay
25%11%27%27%9%1
297
January1st to 10thNight
22%14%23%35%5%
760
11th to 20thNight
28%9%28%30%5%
732
21st to endNight
21%11%33%33%2
792
February1st to 10thNight
23%9%27%37%4
720
11th to 20thNight
27%12%33%26%2
703
21st to endNight
26%11%32%28%3
592
March1st to 10thNight
22%9%27%38%5%
720
11th to 20thNight
21%8%32%30%9%1
720
21st to endNight
20%8%26%36%10%
792
April1st to 10thNight
16%8%28%34%13%1
716
11th to 20thNight
16%8%25%36%15%
533
21st to endNight
17%420%45%14%1
540
May1st to 10thNight
16%6%18%39%19%1
540
11th to 20thNight
16%5%15%35%25%4
531
21st to endNight
8%311%30%41%7%
584
June1st to 10thNight
11%111%34%38%6%
540
11th to 20thNight
5%212%35%37%9%
540
21st to endNight
10%210%33%36%8%
540
July1st to 10thNight
13%25%27%41%11%
525
11th to 20thNight
10%2425%46%13%
522
21st to endNight
8%35%28%44%12%
591
August1st to 10thNight
12%25%23%49%9%
537
11th to 20thNight
12%2430%46%7%
534
21st to endNight
12%2425%46%11%
594
September1st to 10thNight
13%37%28%40%9%
710
11th to 20thNight
16%37%29%38%7%
720
21st to endNight
14%312%36%32%3
720
October1st to 10thNight
14%415%31%29%6%
720
11th to 20thNight
17%5%18%39%20%2
720
21st to endNight
18%5%18%39%18%2
792
November1st to 10thNight
17%5%16%40%20%2
740
11th to 20thNight
18%7%21%42%11%1
760
21st to endNight
17%7%22%41%13%1
760
December1st to 10thNight
25%6%23%37%8%
760
11th to 20thNight
24%8%23%37%9%
760
21st to endNight
24%9%22%38%6%
836
Page generated at 2024-01-10 10:16:09. Version ac07

Copyright 2024 Attilla Danko


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