Crystal Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Crystal Beach clear sky chart from 2005-11-06 to 2024-01-12.

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
59%
23604
23%
74226
19%
23555
63%
23555
30%
44766

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
41%
947
24%
2458
12%
946
47%
946
28%
1676
January11th to 20thNight
46%
910
23%
2366
11%
910
52%
910
29%
1565
January21st to endNight
40%
990
24%
2574
11%
990
47%
990
27%
1757
February1st to 10thNight
41%
882
20%
2322
9%
882
45%
882
25%
1631
February11th to 20thNight
41%
615
20%
2009
13%
611
47%
611
23%
1295
February21st to endNight
35%
444
21%
1628
14%
444
43%
444
17%
1076
March1st to 10thNight
46%
540
23%
1980
17%
540
53%
540
24%
1201
March11th to 20thNight
48%
540
19%
1980
17%
540
53%
540
22%
1238
March21st to endNight
56%
594
25%
2178
23%
594
62%
594
29%
1218
April1st to 10thNight
50%
540
22%
1976
21%
540
56%
540
22%
1227
April11th to 20thNight
47%
533
23%
1775
18%
533
55%
533
27%
1058
April21st to endNight
55%
540
24%
1800
23%
540
60%
540
28%
1071
May1st to 10thNight
59%
540
21%
1800
22%
540
63%
540
27%
1078
May11th to 20thNight
66%
531
24%
1660
27%
531
68%
531
35%
948
May21st to endNight
74%
582
23%
1745
27%
582
75%
582
37%
1002
June1st to 10thNight
83%
540
24%
1620
28%
540
83%
540
44%
856
June11th to 20thNight
81%
540
20%
1620
25%
540
81%
540
41%
885
June21st to endNight
75%
540
17%
1620
21%
540
75%
540
30%
1006
July1st to 10thNight
74%
525
15%
1575
19%
525
74%
525
30%
973
July11th to 20thNight
85%
522
19%
1566
23%
522
85%
522
39%
873
July21st to endNight
83%
591
17%
1673
21%
558
83%
558
39%
933
August1st to 10thNight
90%
537
24%
1601
27%
534
90%
534
53%
777
August11th to 20thNight
81%
534
21%
1754
26%
534
81%
534
37%
953
August21st to endNight
78%
594
16%
1980
19%
594
78%
594
30%
1174
September1st to 10thNight
77%
540
15%
1922
19%
540
77%
540
29%
1112
September11th to 20thNight
67%
540
19%
1980
23%
540
67%
540
22%
1260
September21st to endNight
73%
540
27%
1980
31%
540
74%
540
30%
1088
October1st to 10thNight
76%
674
31%
2114
28%
674
77%
674
43%
1100
October11th to 20thNight
72%
720
33%
2160
26%
720
75%
720
42%
1176
October21st to endNight
62%
792
33%
2376
25%
792
67%
792
40%
1299
November1st to 10thNight
69%
740
28%
2220
24%
740
71%
740
39%
1257
November11th to 20thNight
60%
760
30%
2280
24%
760
64%
760
33%
1349
November21st to endNight
49%
760
28%
2280
19%
760
57%
760
28%
1439
December1st to 10thNight
49%
905
25%
2425
16%
905
54%
905
28%
1626
December11th to 20thNight
45%
948
23%
2876
13%
948
49%
948
24%
1900
December21st to endNight
41%
1034
14%
4353
11%
1026
46%
1026
16%
2689

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
11%5%35%5%35%5%6%9%43%
74973
Night
11%5%25%5%3446%8%46%
74772
TransparencyDay
37%7%15%21%15%6%
74698
Night
36%6%13%21%17%7%
74567
SeeingDay
13%210%24%34%18%
13669
Night
14%313%29%30%10%
23622

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
19%6%35%445%445%41%
1707
11th to 20thDay
16%6%25%6%33347%44%
1634
21st to endDay
19%7%35%5%35%44441%
1782
February1st to 10thDay
20%8%46%5%44445%36%
1652
11th to 20thDay
22%10%46%423335%38%
1835
21st to endDay
21%10%46%5%33346%35%
1628
March1st to 10thDay
18%7%36%5%36%446%37%
1980
11th to 20thDay
16%6%37%5%35%45%5%41%
1980
21st to endDay
13%6%35%32345%8%46%
2178
April1st to 10thDay
15%7%36%435%36%6%41%
1984
11th to 20thDay
13%7%36%5%35%45%8%41%
2134
21st to endDay
9%6%35%4245%5%8%50%
2160
May1st to 10thDay
9%6%35%5%36%6%6%9%43%
2160
11th to 20thDay
9%5%25%6%35%46%9%46%
2231
21st to endDay
7%426%5%37%7%8%14%38%
2531
June1st to 10thDay
44245%45%7%7%12%46%
2340
11th to 20thDay
5%3245%46%7%10%13%42%
2340
21st to endDay
8%425%6%47%7%10%13%34%
2340
July1st to 10thDay
9%5%34426%7%9%14%36%
2340
11th to 20thDay
5%425%5%35%7%9%14%41%
2340
21st to endDay
4425%6%37%7%9%14%40%
2546
August1st to 10thDay
3214436%7%10%15%47%
2328
11th to 20thDay
43145%36%8%10%14%40%
2142
21st to endDay
9%5%35%6%46%6%7%12%37%
2376
September1st to 10thDay
8%5%25%6%46%9%8%12%37%
2032
11th to 20thDay
14%7%36%445%6%6%8%38%
1980
21st to endDay
9%5%146%35%5%6%9%48%
1980
October1st to 10thDay
5%4235%3346%8%57%
1828
11th to 20thDay
10%31443346%7%54%
1800
21st to endDay
12%424423347%56%
1980
November1st to 10thDay
10%5%25%42446%8%50%
1858
11th to 20thDay
12%5%25%5%35%446%48%
1900
21st to endDay
15%7%37%5%2345%5%44%
1900
December1st to 10thDay
16%6%35%42445%7%44%
1751
11th to 20thDay
13%7%36%5%45%5%5%7%41%
2161
21st to endDay
15%7%35%5%3445%7%41%
3135
January1st to 10thNight
18%7%35%5%33445%43%
2458
11th to 20thNight
17%6%35%434445%47%
2366
21st to endNight
18%8%35%5%24445%42%
2574
February1st to 10thNight
19%9%45%6%33346%39%
2322
11th to 20thNight
19%9%35%423346%42%
2009
21st to endNight
19%9%45%6%34345%38%
1628
March1st to 10thNight
18%6%35%42445%8%42%
1980
11th to 20thNight
14%7%36%6%345%5%6%42%
1980
21st to endNight
12%6%2442445%7%51%
2178
April1st to 10thNight
14%6%36%5%345%5%7%41%
1976
11th to 20thNight
14%5%35%5%3436%7%45%
1775
21st to endNight
11%5%26%5%3445%9%44%
1800
May1st to 10thNight
10%5%26%6%36%5%6%9%43%
1800
11th to 20thNight
8%425%6%2447%9%50%
1659
21st to endNight
6%3246%25%6%7%12%47%
1745
June1st to 10thNight
43233335%7%10%56%
1620
11th to 20thNight
5%324435%5%8%13%48%
1620
21st to endNight
7%426%5%47%7%8%14%38%
1620
July1st to 10thNight
7%5%345%36%5%9%13%39%
1620
11th to 20thNight
22245%46%6%8%13%49%
1620
21st to endNight
33244346%7%14%49%
1772
August1st to 10thNight
211232347%12%61%
1611
11th to 20thNight
43145%346%8%13%49%
1754
21st to endNight
6%4245%45%6%7%13%43%
1980
September1st to 10thNight
6%325%6%45%7%7%12%43%
1922
11th to 20thNight
12%7%36%5%45%5%6%8%39%
1980
21st to endNight
8%5%25%5%3446%7%52%
1980
October1st to 10thNight
6%32443445%8%59%
2114
11th to 20thNight
9%4133235%5%8%57%
2160
21st to endNight
12%5%2332335%5%58%
2376
November1st to 10thNight
9%5%2442345%6%55%
2220
11th to 20thNight
13%5%2443445%6%51%
2280
21st to endNight
13%6%37%5%3345%6%46%
2280
December1st to 10thNight
17%8%35%5%2345%7%41%
2425
11th to 20thNight
14%8%35%5%2445%7%42%
3036
21st to endNight
16%7%35%5%3435%5%43%
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
45%45%18%19%8%
1708
11th to 20thDay
41%47%17%21%10%
1634
21st to endDay
46%45%17%15%12%
1782
February1st to 10thDay
50%5%5%16%14%10%
1652
11th to 20thDay
51%38%14%17%8%
1845
21st to endDay
51%5%9%13%15%8%
1628
March1st to 10thDay
48%5%10%15%17%5%
1980
11th to 20thDay
45%411%13%19%8%
1980
21st to endDay
38%414%17%21%5%
2178
April1st to 10thDay
43%6%11%17%16%7%
1984
11th to 20thDay
42%6%12%18%14%8%
2134
21st to endDay
32%6%12%24%20%5%
2160
May1st to 10thDay
36%8%15%19%17%6%
2160
11th to 20thDay
33%7%13%29%15%3
2235
21st to endDay
33%9%18%28%11%1
2531
June1st to 10thDay
28%9%18%30%14%
2340
11th to 20thDay
28%10%19%29%12%1
2340
21st to endDay
38%9%22%24%7%
2340
July1st to 10thDay
33%10%28%25%4
2276
11th to 20thDay
29%11%30%25%5%
2271
21st to endDay
29%12%28%26%41
2405
August1st to 10thDay
21%10%30%31%8%
2314
11th to 20thDay
28%12%27%27%41
2142
21st to endDay
37%10%22%23%6%1
2376
September1st to 10thDay
36%12%19%19%12%3
2032
11th to 20thDay
42%10%13%20%12%2
1980
21st to endDay
32%6%15%24%16%7%
1980
October1st to 10thDay
25%411%30%20%10%
1828
11th to 20thDay
29%6%9%23%23%12%
1800
21st to endDay
30%47%20%24%15%
1980
November1st to 10thDay
32%412%24%20%8%
1858
11th to 20thDay
36%5%10%18%20%11%
1900
21st to endDay
43%48%19%19%8%
1900
December1st to 10thDay
39%6%12%22%15%6%
1751
11th to 20thDay
42%6%9%15%18%9%
2159
21st to endDay
42%49%14%21%9%
3135
January1st to 10thNight
44%46%16%20%10%
2458
11th to 20thNight
41%46%16%20%12%
2366
21st to endNight
45%46%15%18%12%
2574
February1st to 10thNight
49%38%11%18%11%
2322
11th to 20thNight
45%47%16%17%11%
2009
21st to endNight
49%5%8%13%15%10%
1628
March1st to 10thNight
40%5%11%19%16%8%
1980
11th to 20thNight
43%5%13%13%18%8%
1980
21st to endNight
33%5%12%20%21%8%
2178
April1st to 10thNight
41%6%10%19%16%9%
1976
11th to 20thNight
37%5%12%19%14%12%
1775
21st to endNight
37%5%11%22%18%7%
1800
May1st to 10thNight
36%7%12%21%16%8%
1800
11th to 20thNight
30%7%12%28%20%4
1660
21st to endNight
28%9%19%29%15%1
1746
June1st to 10thNight
21%8%19%35%16%
1620
11th to 20thNight
26%6%19%31%16%1
1620
21st to endNight
34%9%23%24%10%
1620
July1st to 10thNight
34%9%26%27%5%
1575
11th to 20thNight
24%9%33%28%6%
1566
21st to endNight
23%11%30%31%5%
1673
August1st to 10thNight
15%7%30%39%8%
1601
11th to 20thNight
25%9%29%31%5%1
1754
21st to endNight
31%10%25%25%7%2
1980
September1st to 10thNight
32%9%23%20%13%3
1922
11th to 20thNight
42%7%15%18%14%3
1980
21st to endNight
32%6%14%23%19%7%
1980
October1st to 10thNight
25%411%28%21%12%
2114
11th to 20thNight
26%5%9%26%21%13%
2160
21st to endNight
29%38%17%25%17%
2376
November1st to 10thNight
30%412%24%21%9%
2220
11th to 20thNight
34%49%21%21%10%
2280
21st to endNight
40%49%21%19%7%
2280
December1st to 10thNight
43%410%20%14%8%
2425
11th to 20thNight
42%5%7%15%18%14%
3037
21st to endNight
44%5%7%14%22%8%
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
24%6%21%34%14%1
270
11th to 20thDay
18%6%20%35%19%1
245
21st to endDay
21%6%23%38%12%
264
February1st to 10thDay
27%220%34%16%1
240
11th to 20thDay
32%5%20%30%10%3
240
21st to endDay
28%424%38%6%1
198
March1st to 10thDay
23%123%39%14%
240
11th to 20thDay
18%424%40%12%2
240
21st to endDay
16%325%40%13%2
264
April1st to 10thDay
15%225%42%14%
244
11th to 20thDay
21%422%30%21%3
412
21st to endDay
14%319%39%21%3
420
May1st to 10thDay
15%214%39%27%2
423
11th to 20thDay
11%110%35%36%6%
554
21st to endDay
8%17%35%42%7%
679
June1st to 10thDay
7%1224%51%16%
630
11th to 20thDay
7%1321%52%17%
630
21st to endDay
10%2214%44%28%
630
July1st to 10thDay
8%1110%43%37%
621
11th to 20thDay
5%16%44%43%
618
21st to endDay
5%116%52%34%
684
August1st to 10thDay
31445%46%
626
11th to 20thDay
42340%51%
456
21st to endDay
12%217%35%43%
495
September1st to 10thDay
11%210%42%36%
322
11th to 20thDay
13%219%40%33%
270
21st to endDay
14%119%48%27%
270
October1st to 10thDay
9%126%47%17%
270
11th to 20thDay
11%16%27%36%19%
270
21st to endDay
18%417%26%30%5%
297
November1st to 10thDay
14%17%31%38%9%
270
11th to 20thDay
19%113%33%30%4
270
21st to endDay
18%424%33%18%3
270
December1st to 10thDay
17%211%39%21%9%
270
11th to 20thDay
22%323%34%17%
270
21st to endDay
21%419%36%19%2
297
January1st to 10thNight
22%5%22%34%15%1
950
11th to 20thNight
20%5%20%38%15%
910
21st to endNight
22%5%25%36%12%
990
February1st to 10thNight
24%6%20%38%12%
882
11th to 20thNight
25%6%22%33%13%
615
21st to endNight
25%5%25%37%9%
444
March1st to 10thNight
20%424%35%17%1
540
11th to 20thNight
18%420%39%18%2
540
21st to endNight
15%319%41%20%2
594
April1st to 10thNight
16%321%41%19%1
540
11th to 20thNight
17%5%22%35%20%1
533
21st to endNight
13%419%41%21%2
540
May1st to 10thNight
13%217%44%24%
540
11th to 20thNight
11%211%42%30%4
531
21st to endNight
7%17%34%43%8%
584
June1st to 10thNight
6%1226%55%11%
540
11th to 20thNight
5%1321%54%16%
540
21st to endNight
7%1314%50%24%
540
July1st to 10thNight
8%2210%47%32%
525
11th to 20thNight
215%49%43%
522
21st to endNight
4227%53%33%
591
August1st to 10thNight
2115%55%36%
537
11th to 20thNight
5%1348%43%
534
21st to endNight
8%2112%49%29%
594
September1st to 10thNight
8%1112%44%34%
540
11th to 20thNight
14%1215%48%20%
540
21st to endNight
9%1417%52%17%
540
October1st to 10thNight
7%15%23%49%15%
674
11th to 20thNight
10%210%30%37%12%
720
21st to endNight
13%414%30%32%7%
792
November1st to 10thNight
10%210%33%37%7%
740
11th to 20thNight
16%216%35%28%3
760
21st to endNight
16%421%37%18%4
760
December1st to 10thNight
21%5%16%31%24%4
905
11th to 20thNight
21%420%38%17%1
950
21st to endNight
22%7%20%34%17%1
1045
Page generated at 2024-01-09 15:24:27. Version ac07

Copyright 2024 Attilla Danko


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