Cosmic Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cosmic Campground clear sky chart from 2005-11-05 to 2017-12-20.

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
67%
15705
33%
48007
26%
15662
74%
15662
46%
24018

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 15thNight
59%
720
31%
2327
27%
716
69%
716
45%
1147
January16th to endNight
57%
768
34%
2496
29%
768
68%
768
41%
1268
February1st to 15thNight
59%
701
32%
2285
26%
699
71%
699
45%
1100
February16th to endNight
51%
632
40%
1799
26%
632
66%
632
47%
930
March1st to 15thNight
58%
720
38%
1980
25%
720
69%
720
51%
996
March16th to endNight
62%
768
37%
2112
23%
768
73%
768
56%
1025
April1st to 15thNight
53%
599
34%
1858
18%
599
69%
599
48%
866
April16th to endNight
55%
540
42%
1800
27%
540
76%
540
57%
712
May1st to 15thNight
64%
539
33%
1703
26%
539
73%
539
56%
739
May16th to endNight
69%
562
35%
1684
26%
561
77%
561
59%
739
June1st to 15thNight
77%
540
32%
1620
28%
540
80%
540
62%
709
June16th to endNight
79%
540
24%
1620
22%
540
80%
540
51%
792
July1st to 15thNight
75%
510
16%
1530
14%
510
75%
510
30%
928
July16th to endNight
78%
564
12%
1593
12%
531
77%
531
27%
1025
August1st to 15thNight
79%
539
18%
1620
17%
536
79%
536
29%
1007
August16th to endNight
77%
573
22%
1910
24%
573
78%
573
28%
1165
September1st to 15thNight
74%
579
24%
1839
25%
579
75%
579
30%
1124
September16th to endNight
77%
716
38%
1989
29%
716
82%
716
58%
979
October1st to 15thNight
72%
720
37%
2160
28%
720
78%
720
59%
980
October16th to endNight
78%
768
44%
2304
34%
768
85%
768
66%
1003
November1st to 15thNight
73%
760
40%
2280
31%
760
81%
760
63%
990
November16th to endNight
66%
780
41%
2405
34%
780
74%
780
49%
1167
December1st to 15thNight
62%
780
35%
2535
30%
780
70%
780
44%
1259
December16th to endNight
55%
787
32%
2558
27%
787
64%
787
37%
1368

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
431342445%6%59%
48832
Night
3313323346%63%
48206
TransparencyDay
24%5%7%15%28%19%
48527
Night
21%48%17%29%18%
48012
SeeingDay
8%15%29%28%14%3
5511
Night
5%417%38%29%4
15710

By Month

Percentage Cloud Cover SW (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 15thDay
5%413313445%62%
1611
16th to endDay
7%412323235%61%
1728
February1st to 15thDay
341421223467%
1575
16th to endDay
35%1332325%5%62%
1674
March1st to 15thDay
4412213347%63%
1980
16th to endDay
3212213246%68%
2112
April1st to 15thDay
2212223346%67%
2090
16th to endDay
1113222336%71%
2160
May1st to 15thDay
112224446%69%
2244
16th to endDay
2112223345%69%
2429
June1st to 15thDay
113213346%70%
2340
16th to endDay
22134245%5%7%59%
2340
July1st to 15thDay
6%327%8%47%7%7%9%35%
2340
16th to endDay
6%5%37%8%5%8%8%8%11%26%
2467
August1st to 15thDay
6%437%8%47%6%6%9%35%
2329
16th to endDay
5%425%7%47%6%7%8%38%
2292
September1st to 15thDay
7%426%7%36%5%7%7%41%
2118
16th to endDay
4212423347%63%
1971
October1st to 15thDay
4112223336%68%
1800
16th to endDay
21221232475%
1920
November1st to 15thDay
212222245%72%
1909
16th to endDay
321221323470%
1884
December1st to 15thDay
5%413223336%62%
1755
16th to endDay
7%5%23424336%57%
1764
January1st to 15thNight
5%412313346%63%
2327
16th to endNight
6%412323245%63%
2496
February1st to 15thNight
4412313235%67%
2277
16th to endNight
431222435%6%64%
1799
March1st to 15thNight
4212322345%68%
1980
16th to endNight
3212212235%72%
2112
April1st to 15thNight
221231435%7%65%
1858
16th to endNight
11111223479%
1800
May1st to 15thNight
1212212236%72%
1703
16th to endNight
41112245%74%
1684
June1st to 15thNight
1112212326%74%
1620
16th to endNight
111332446%7%63%
1620
July1st to 15thNight
2416%6%46%7%9%10%40%
1620
16th to endNight
2325%5%47%8%10%13%35%
1701
August1st to 15thNight
2215%5%46%8%8%10%43%
1629
16th to endNight
44245%45%7%7%9%43%
1910
September1st to 15thNight
5%426%6%35%5%6%9%43%
1839
16th to endNight
3213222336%69%
1989
October1st to 15thNight
21231323474%
2160
16th to endNight
111111223378%
2304
November1st to 15thNight
111211346%74%
2280
16th to endNight
5%212212235%68%
2405
December1st to 15thNight
5%5%13212336%63%
2535
16th to endNight
8%413224346%57%
2558

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 15thDay
24%37%16%31%17%
1612
16th to endDay
26%3415%34%15%
1728
February1st to 15thDay
22%26%16%28%23%
1575
16th to endDay
24%3418%34%14%
1674
March1st to 15thDay
21%2412%38%20%
1980
16th to endDay
17%2414%41%19%
2112
April1st to 15thDay
18%2415%37%20%
2090
16th to endDay
16%2413%35%28%
2160
May1st to 15thDay
14%45%14%32%28%
2244
16th to endDay
16%35%11%31%30%
2432
June1st to 15thDay
13%35%8%27%42%
2340
16th to endDay
21%5%7%10%21%33%
2340
July1st to 15thDay
39%9%14%16%9%11%
2201
16th to endDay
43%15%21%14%4
2312
August1st to 15thDay
40%10%14%14%15%4
2314
16th to endDay
37%9%14%17%15%5%
2292
September1st to 15thDay
37%7%12%16%17%8%
2118
16th to endDay
20%46%16%32%20%
1971
October1st to 15thDay
17%37%12%33%25%
1800
16th to endDay
14%2415%36%26%
1920
November1st to 15thDay
15%2420%34%22%
1909
16th to endDay
18%3414%34%24%
1884
December1st to 15thDay
23%36%22%29%14%
1755
16th to endDay
31%38%21%26%8%
1764
January1st to 15thNight
22%36%17%34%15%
2327
16th to endNight
25%35%17%34%12%
2496
February1st to 15thNight
21%26%19%29%20%
2288
16th to endNight
21%3421%34%14%
1799
March1st to 15thNight
18%35%15%38%18%
1980
16th to endNight
16%2416%42%18%
2112
April1st to 15thNight
18%3418%38%17%
1858
16th to endNight
10%2415%40%25%
1800
May1st to 15thNight
14%26%14%37%24%
1704
16th to endNight
12%36%14%31%30%
1685
June1st to 15thNight
13%249%27%42%
1620
16th to endNight
17%6%8%11%21%34%
1620
July1st to 15thNight
31%10%18%15%12%12%
1530
16th to endNight
32%14%29%17%5%
1593
August1st to 15thNight
30%13%18%17%14%5%
1620
16th to endNight
32%11%16%18%15%5%
1910
September1st to 15thNight
35%7%14%17%16%8%
1839
16th to endNight
17%26%19%33%20%
1989
October1st to 15thNight
15%26%18%32%24%
2160
16th to endNight
11%2419%31%29%
2304
November1st to 15thNight
11%35%22%34%22%
2280
16th to endNight
20%3314%32%25%
2405
December1st to 15thNight
24%26%21%28%16%
2535
16th to endNight
28%310%21%28%6%
2558

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 15thDay
20%13%30%23%13%
90
16th to endDay
9%15%23%31%12%7%
96
February1st to 15thDay
5%7%30%36%13%6%
90
16th to endDay
13%34%30%14%5%2
198
March1st to 15thDay
11%24%37%17%7%2
270
16th to endDay
11%31%31%18%5%1
288
April1st to 15thDay
11%30%34%15%5%1
269
16th to endDay
15%27%38%14%21
270
May1st to 15thDay
9%27%40%17%31
288
16th to endDay
5%20%46%20%6%2
330
June1st to 15thDay
313%45%23%9%4
315
16th to endDay
47%30%37%16%4
315
July1st to 15thDay
11%318%40%21%4
305
16th to endDay
8%211%33%32%11%
327
August1st to 15thDay
7%211%44%25%7%
315
16th to endDay
7%216%44%22%6%
332
September1st to 15thDay
11%427%36%18%2
315
16th to endDay
5%14%33%34%9%2
306
October1st to 15thDay
11%33%28%21%5%
135
16th to endDay
2425%34%27%6%
144
November1st to 15thDay
414%30%31%17%2
135
16th to endDay
6%18%28%28%14%2
135
December1st to 15thDay
413%27%29%22%2
135
16th to endDay
19%18%18%35%6%1
108
January1st to 15thNight
7%5%24%40%17%5%
720
16th to endNight
10%423%36%20%4
768
February1st to 15thNight
6%6%23%41%19%3
704
16th to endNight
7%7%31%40%12%
632
March1st to 15thNight
6%8%24%39%20%1
720
16th to endNight
5%8%20%43%19%2
768
April1st to 15thNight
5%10%26%39%16%
599
16th to endNight
410%28%40%15%1
540
May1st to 15thNight
26%24%43%22%1
540
16th to endNight
4419%46%23%2
563
June1st to 15thNight
2114%50%28%2
540
16th to endNight
1110%39%44%3
540
July1st to 15thNight
4426%54%9%
510
16th to endNight
4418%59%13%
564
August1st to 15thNight
3220%56%16%
539
16th to endNight
6%423%56%8%
573
September1st to 15thNight
6%6%33%47%6%
579
16th to endNight
410%39%38%6%
716
October1st to 15thNight
3217%44%29%3
720
16th to endNight
2114%40%34%6%
768
November1st to 15thNight
3218%41%30%4
760
16th to endNight
6%5%18%35%28%5%
780
December1st to 15thNight
11%319%41%20%2
780
16th to endNight
11%6%22%42%13%3
787
Page generated at 2017-12-21 05:04:42. Version ac04

Copyright 2017 A. Danko


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