Pointed Rock Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pointed Rock Observatory clear sky chart from 2005-11-06 to 2024-03-08.

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
73%
24181
35%
79509
31%
24090
78%
24090
50%
37017

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
67%
752
39%
3984
31%
736
74%
736
36%
1492
January11th to 20thNight
68%
752
47%
3873
34%
740
77%
740
46%
1223
January21st to endNight
61%
829
23%
4295
31%
814
71%
814
24%
2274
February1st to 10thNight
65%
760
36%
2421
34%
760
74%
760
49%
1164
February11th to 20thNight
61%
740
34%
2219
29%
740
71%
740
46%
1137
February21st to endNight
55%
628
35%
1799
27%
628
65%
628
48%
936
March1st to 10thNight
60%
750
37%
2062
26%
750
71%
750
52%
1051
March11th to 20thNight
70%
720
38%
1980
29%
720
76%
720
57%
983
March21st to endNight
67%
792
38%
2178
26%
792
76%
792
56%
1077
April1st to 10thNight
72%
720
37%
1980
27%
720
80%
720
65%
916
April11th to 20thNight
65%
578
41%
1822
33%
578
76%
578
63%
748
April21st to endNight
73%
540
47%
1760
41%
540
82%
540
72%
654
May1st to 10thNight
73%
540
42%
1620
33%
540
81%
540
71%
651
May11th to 20thNight
75%
531
42%
1594
35%
531
80%
531
69%
656
May21st to endNight
78%
582
44%
1746
37%
582
83%
582
80%
662
June1st to 10thNight
82%
540
36%
1620
31%
540
83%
540
68%
681
June11th to 20thNight
86%
540
39%
1620
33%
540
87%
540
78%
624
June21st to endNight
83%
540
30%
1620
26%
540
84%
540
58%
749
July1st to 10thNight
82%
525
24%
1575
20%
525
82%
525
44%
833
July11th to 20thNight
83%
522
20%
1566
17%
522
83%
522
36%
912
July21st to endNight
78%
591
17%
1674
14%
558
78%
558
29%
1050
August1st to 10thNight
85%
537
25%
1602
23%
534
85%
534
46%
839
August11th to 20thNight
79%
534
29%
1602
27%
534
79%
534
39%
888
August21st to endNight
85%
639
31%
2011
32%
639
85%
639
43%
1059
September1st to 10thNight
77%
720
31%
1980
28%
720
78%
720
44%
1112
September11th to 20thNight
85%
720
40%
1980
34%
720
86%
720
60%
963
September21st to endNight
80%
720
38%
1980
29%
720
84%
720
60%
959
October1st to 10thNight
77%
720
39%
2050
31%
720
82%
720
61%
963
October11th to 20thNight
81%
720
43%
2160
37%
720
87%
720
70%
886
October21st to endNight
79%
792
45%
2376
39%
792
85%
792
71%
977
November1st to 10thNight
77%
740
43%
2220
37%
740
82%
740
65%
956
November11th to 20thNight
76%
760
42%
2318
37%
760
82%
760
63%
1006
November21st to endNight
63%
760
37%
2470
34%
760
71%
760
47%
1197
December1st to 10thNight
67%
760
37%
2470
36%
760
73%
760
47%
1186
December11th to 20thNight
62%
760
32%
2942
33%
758
70%
758
34%
1564
December21st to endNight
62%
827
23%
4340
34%
817
69%
817
27%
1989

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
4313323446%65%
79058
Night
5%313323446%65%
80571
TransparencyDay
20%36%11%25%35%
78785
Night
19%36%12%26%33%
80366
SeeingDay
6%7%22%33%25%8%
13976
Night
5%214%40%33%5%
24219

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 10thDay
8%5%2432334463%
2858
11th to 20thDay
5%424323335%66%
2860
21st to endDay
10%6%2332345%8%54%
3146
February1st to 10thDay
7%412322345%66%
1755
11th to 20thDay
9%42432335%461%
1850
21st to endDay
9%423223346%62%
1653
March1st to 10thDay
6%314324446%63%
2058
11th to 20thDay
6%412322345%66%
1980
21st to endDay
421332233472%
2178
April1st to 10thDay
221221245%6%73%
1980
11th to 20thDay
321211222479%
2085
21st to endDay
2212113235%79%
2196
May1st to 10thDay
121121333479%
2340
11th to 20thDay
111221224478%
2301
21st to endDay
11111122286%
2530
June1st to 10thDay
3212112236%77%
2340
11th to 20thDay
11121222385%
2340
21st to endDay
221332345%6%69%
2340
July1st to 10thDay
32145%45%7%6%8%55%
2340
11th to 20thDay
45%25%6%46%8%10%10%40%
2340
21st to endDay
8%427%7%48%8%8%12%33%
2545
August1st to 10thDay
5%4245%45%6%6%8%50%
2328
11th to 20thDay
34145%36%6%8%11%47%
2299
21st to endDay
33145%46%6%6%9%54%
2335
September1st to 10thDay
6%3244245%6%6%58%
1980
11th to 20thDay
3112324336%72%
1980
21st to endDay
321332335%5%71%
1980
October1st to 10thDay
222324446%72%
1908
11th to 20thDay
21221223382%
1800
21st to endDay
121222333477%
1980
November1st to 10thDay
221212347%76%
1859
11th to 20thDay
2213323445%73%
1859
21st to endDay
6%42432345%7%63%
1710
December1st to 10thDay
8%21333445%7%61%
1710
11th to 20thDay
8%6%36%42346%7%52%
2169
21st to endDay
9%5%24424445%58%
3146
January1st to 10thNight
6%5%13323446%62%
4097
11th to 20thNight
4212222335%74%
4110
21st to endNight
14%6%24324347%50%
4521
February1st to 10thNight
7%423313345%65%
2421
11th to 20thNight
7%423324446%61%
2218
21st to endNight
8%5%23324345%62%
1799
March1st to 10thNight
5%32333345%7%64%
2062
11th to 20thNight
6%313313235%69%
1980
21st to endNight
4322322346%69%
2178
April1st to 10thNight
2212223346%73%
1980
11th to 20thNight
221222232478%
1822
21st to endNight
3111112125%83%
1760
May1st to 10thNight
111212345%79%
1620
11th to 20thNight
2112213335%79%
1594
21st to endNight
1111221387%
1746
June1st to 10thNight
2212222336%75%
1620
11th to 20thNight
11112222484%
1620
21st to endNight
22133235%35%71%
1620
July1st to 10thNight
3324436%6%7%8%55%
1620
11th to 20thNight
22245%48%7%10%14%41%
1620
21st to endNight
4425%7%47%9%10%16%33%
1773
August1st to 10thNight
22235%25%6%8%11%55%
1611
11th to 20thNight
34246%35%48%9%51%
1602
21st to endNight
32144347%8%11%52%
2011
September1st to 10thNight
5%4245%335%5%8%56%
1980
11th to 20thNight
2213323335%73%
1980
21st to endNight
2213323346%70%
1980
October1st to 10thNight
2212323445%71%
2050
11th to 20thNight
221212245%79%
2160
21st to endNight
221221223481%
2376
November1st to 10thNight
2212222336%74%
2220
11th to 20thNight
3212312336%74%
2318
21st to endNight
8%313323446%63%
2470
December1st to 10thNight
8%413322446%63%
2470
11th to 20thNight
8%5%26%434446%54%
3041
21st to endNight
9%5%243245%4457%
4521

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
25%25%10%35%23%
2859
11th to 20thDay
21%35%12%37%22%
2860
21st to endDay
27%48%16%28%16%
3146
February1st to 10thDay
21%25%12%23%38%
1755
11th to 20thDay
26%35%12%24%30%
1860
21st to endDay
23%2311%28%32%
1653
March1st to 10thDay
22%249%30%32%
2058
11th to 20thDay
20%248%26%39%
1980
21st to endDay
17%238%34%35%
2178
April1st to 10thDay
12%227%36%42%
1980
11th to 20thDay
11%126%26%53%
2088
21st to endDay
10%138%27%51%
2196
May1st to 10thDay
10%137%21%58%
2340
11th to 20thDay
11%239%22%53%
2304
21st to endDay
7%115%23%63%
2530
June1st to 10thDay
11%13424%58%
2340
11th to 20thDay
7%12216%72%
2340
21st to endDay
16%35%8%19%50%
2340
July1st to 10thDay
24%7%9%13%17%29%
2276
11th to 20thDay
32%10%17%20%14%7%
2271
21st to endDay
38%11%17%19%11%4
2404
August1st to 10thDay
29%7%13%15%19%18%
2313
11th to 20thDay
27%8%14%17%20%13%
2299
21st to endDay
26%8%10%20%20%16%
2335
September1st to 10thDay
26%5%6%19%20%23%
1980
11th to 20thDay
16%45%12%26%38%
1980
21st to endDay
16%349%29%38%
1980
October1st to 10thDay
13%46%13%26%38%
1908
11th to 20thDay
9%238%25%53%
1800
21st to endDay
12%2410%25%49%
1980
November1st to 10thDay
11%1311%37%37%
1859
11th to 20thDay
15%3310%29%41%
1859
21st to endDay
22%4411%24%35%
1710
December1st to 10thDay
23%37%14%26%27%
1710
11th to 20thDay
31%35%17%24%20%
2168
21st to endDay
27%36%13%31%19%
3146
January1st to 10thNight
21%26%10%41%20%
4097
11th to 20thNight
14%2417%42%22%
4110
21st to endNight
34%46%14%28%14%
4521
February1st to 10thNight
22%25%13%22%37%
2421
11th to 20thNight
24%35%13%27%28%
2219
21st to endNight
24%35%10%29%30%
1799
March1st to 10thNight
21%25%11%28%33%
2062
11th to 20thNight
18%2310%24%42%
1980
21st to endNight
18%2313%33%31%
2178
April1st to 10thNight
13%239%34%39%
1980
11th to 20thNight
13%128%26%50%
1822
21st to endNight
8%128%29%52%
1760
May1st to 10thNight
9%249%24%53%
1620
11th to 20thNight
10%339%22%53%
1595
21st to endNight
6%115%24%63%
1746
June1st to 10thNight
11%23423%57%
1620
11th to 20thNight
7%12315%72%
1620
21st to endNight
15%45%6%16%55%
1620
July1st to 10thNight
23%6%11%14%14%32%
1575
11th to 20thNight
26%11%17%24%14%7%
1566
21st to endNight
32%12%23%18%11%4
1674
August1st to 10thNight
19%9%14%21%17%19%
1602
11th to 20thNight
27%7%15%19%18%15%
1602
21st to endNight
22%8%13%21%20%16%
2011
September1st to 10thNight
25%6%8%22%17%22%
1980
11th to 20thNight
15%45%12%28%36%
1980
21st to endNight
16%35%10%28%38%
1980
October1st to 10thNight
14%36%15%24%38%
2050
11th to 20thNight
9%2310%25%51%
2160
21st to endNight
10%1310%26%49%
2376
November1st to 10thNight
13%2311%32%39%
2220
11th to 20thNight
14%2412%29%40%
2318
21st to endNight
23%2411%27%32%
2470
December1st to 10thNight
22%3416%25%30%
2470
11th to 20thNight
30%36%14%25%21%
3041
21st to endNight
28%46%11%29%22%
4521

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
10%7%23%37%22%1
270
11th to 20thDay
10%324%38%18%7%
270
21st to endDay
7%5%25%39%19%5%
297
February1st to 10thDay
8%8%29%29%19%7%
315
11th to 20thDay
14%12%30%34%10%1
455
21st to endDay
13%14%36%25%10%1
382
March1st to 10thDay
10%13%30%35%10%3
449
11th to 20thDay
9%13%27%31%17%4
420
21st to endDay
6%17%33%30%12%2
462
April1st to 10thDay
414%31%28%17%6%
420
11th to 20thDay
317%33%32%11%4
412
21st to endDay
214%31%31%16%6%
420
May1st to 10thDay
412%34%28%17%6%
423
11th to 20thDay
28%29%38%19%4
448
21st to endDay
28%33%36%17%5%
485
June1st to 10thDay
4423%40%21%6%
450
11th to 20thDay
2322%41%24%7%
450
21st to endDay
4116%43%28%8%
450
July1st to 10thDay
319%36%40%12%
446
11th to 20thDay
47%29%41%19%
444
21st to endDay
6%25%24%42%21%
487
August1st to 10thDay
37%32%43%15%
447
11th to 20thDay
5%15%26%44%19%
437
21st to endDay
316%24%41%25%
495
September1st to 10thDay
7%212%33%35%10%
450
11th to 20thDay
3115%34%35%12%
450
21st to endDay
45%22%28%28%12%
450
October1st to 10thDay
37%19%37%24%10%
378
11th to 20thDay
4116%39%33%7%
270
21st to endDay
2416%36%32%9%
297
November1st to 10thDay
46%20%43%24%3
270
11th to 20thDay
5%220%35%33%4
270
21st to endDay
6%10%21%39%20%4
270
December1st to 10thDay
10%424%31%26%4
270
11th to 20thDay
8%7%26%40%16%3
270
21st to endDay
13%10%27%27%19%4
297
January1st to 10thNight
8%216%44%25%5%
760
11th to 20thNight
7%317%43%25%5%
760
21st to endNight
11%318%43%22%3
836
February1st to 10thNight
9%318%41%23%6%
760
11th to 20thNight
8%421%47%18%2
744
21st to endNight
9%5%24%44%16%2
628
March1st to 10thNight
6%426%46%17%2
750
11th to 20thNight
7%316%40%28%6%
720
21st to endNight
5%420%44%25%3
792
April1st to 10thNight
2418%51%22%3
720
11th to 20thNight
35%23%45%22%1
578
21st to endNight
3319%49%23%3
540
May1st to 10thNight
1419%50%23%2
540
11th to 20thNight
2218%50%27%3
531
21st to endNight
2216%50%28%2
584
June1st to 10thNight
2111%48%36%2
540
11th to 20thNight
129%50%35%3
540
21st to endNight
218%37%49%3
540
July1st to 10thNight
31427%59%5%
525
11th to 20thNight
2319%67%9%
522
21st to endNight
5%1218%61%14%
591
August1st to 10thNight
31117%65%14%
537
11th to 20thNight
41322%62%8%
534
21st to endNight
4220%61%13%
639
September1st to 10thNight
6%15%27%49%11%
720
11th to 20thNight
215%38%44%10%
720
21st to endNight
3211%39%39%6%
720
October1st to 10thNight
3113%46%31%5%
720
11th to 20thNight
3212%45%34%6%
720
21st to endNight
2213%41%33%9%
792
November1st to 10thNight
3114%44%31%6%
740
11th to 20thNight
3114%44%33%4
760
21st to endNight
9%419%41%23%6%
760
December1st to 10thNight
9%215%43%27%4
760
11th to 20thNight
8%418%45%19%5%
760
21st to endNight
10%317%43%22%5%
836
Page generated at 2024-03-05 05:24:04. Version ac07

Copyright © 2024 Attilla Danko.


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