Stony Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stony Ridge Observatory clear sky chart from 2005-11-06 to 2024-01-14.

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
60%
24369
35%
74339
25%
24306
71%
24306
50%
35725

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
39%
760
28%
2646
16%
756
57%
756
32%
1347
January11th to 20thNight
38%
734
36%
2402
20%
734
61%
734
39%
1159
January21st to endNight
35%
792
36%
2376
16%
792
58%
792
35%
1282
February1st to 10thNight
44%
720
35%
2160
22%
720
61%
720
40%
1127
February11th to 20thNight
42%
700
34%
2098
20%
700
60%
700
41%
1077
February21st to endNight
39%
592
29%
1776
19%
592
55%
592
34%
1003
March1st to 10thNight
42%
720
25%
2160
16%
720
56%
720
33%
1226
March11th to 20thNight
51%
720
26%
2114
20%
720
60%
720
39%
1126
March21st to endNight
46%
792
32%
1980
15%
792
58%
792
41%
1146
April1st to 10thNight
51%
720
32%
1800
15%
720
61%
720
48%
1014
April11th to 20thNight
53%
711
34%
1779
15%
711
62%
711
52%
939
April21st to endNight
57%
720
34%
1800
14%
720
65%
720
57%
917
May1st to 10thNight
58%
644
32%
1724
17%
644
64%
644
53%
882
May11th to 20thNight
68%
531
37%
1595
26%
531
72%
531
58%
718
May21st to endNight
67%
582
35%
1746
24%
582
73%
582
63%
743
June1st to 10thNight
78%
529
34%
1609
28%
529
81%
529
67%
671
June11th to 20thNight
84%
360
42%
1440
43%
360
92%
360
79%
427
June21st to endNight
86%
360
42%
1440
48%
360
91%
360
75%
443
July1st to 10thNight
90%
350
40%
1400
47%
350
91%
350
77%
419
July11th to 20thNight
91%
379
39%
1423
43%
379
91%
379
63%
518
July21st to endNight
88%
730
35%
1806
25%
690
89%
690
68%
861
August1st to 10thNight
88%
716
36%
1780
23%
712
89%
712
78%
824
August11th to 20thNight
92%
712
42%
1780
26%
712
93%
712
86%
780
August21st to endNight
90%
792
45%
1980
31%
792
90%
792
79%
903
September1st to 10thNight
88%
720
44%
1800
33%
720
90%
720
78%
821
September11th to 20thNight
86%
720
47%
1938
39%
720
90%
720
82%
808
September21st to endNight
75%
720
45%
1980
34%
720
86%
720
76%
846
October1st to 10thNight
66%
720
39%
1980
29%
720
77%
720
59%
969
October11th to 20thNight
66%
720
44%
2082
36%
720
78%
720
63%
908
October21st to endNight
60%
792
43%
2428
32%
792
76%
792
54%
1075
November1st to 10thNight
58%
740
37%
2405
29%
740
73%
740
52%
1067
November11th to 20thNight
51%
760
38%
2470
25%
760
71%
760
51%
1106
November21st to endNight
45%
760
35%
2470
23%
760
62%
760
39%
1248
December1st to 10thNight
43%
760
33%
2470
21%
760
60%
760
35%
1295
December11th to 20thNight
38%
760
28%
2979
18%
759
56%
759
23%
1787
December21st to endNight
34%
831
20%
4523
16%
817
54%
817
20%
2243

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
4413323345%69%
75032
Night
4413323345%67%
74730
TransparencyDay
18%36%15%28%28%
74756
Night
19%36%14%27%30%
74528
SeeingDay
8%14%35%31%9%3
14435
Night
6%7%22%34%25%5%
24380

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%6%2441345%8%56%
1519
11th to 20thDay
8%41342335%7%60%
1618
21st to endDay
10%8%25%32335%6%56%
1980
February1st to 10thDay
8%5%23323345%62%
1800
11th to 20thDay
8%6%2421335%6%60%
1750
21st to endDay
8%9%34323345%57%
1480
March1st to 10thDay
9%8%25%5%335%5%8%47%
1800
11th to 20thDay
6%8%2442346%9%53%
1839
21st to endDay
6%5%2443445%6%57%
2376
April1st to 10thDay
7%5%2332245%8%59%
2160
11th to 20thDay
4323223346%69%
2129
21st to endDay
432221335%6%69%
2160
May1st to 10thDay
45%1332245%7%65%
2236
11th to 20thDay
3312222346%72%
2301
21st to endDay
4313322345%71%
2530
June1st to 10thDay
2312213346%73%
2344
11th to 20thDay
111111222485%
2520
21st to endDay
111121122385%
2520
July1st to 10thDay
111121223480%
2520
11th to 20thDay
211222223479%
2484
21st to endDay
211231345%7%72%
2402
August1st to 10thDay
21221222484%
2149
11th to 20thDay
1121113484%
2122
21st to endDay
111232223481%
2376
September1st to 10thDay
21221224479%
2160
11th to 20thDay
1111122387%
2021
21st to endDay
121221233481%
1980
October1st to 10thDay
4313222335%71%
1980
11th to 20thDay
311231223380%
1873
21st to endDay
2212212325%77%
1926
November1st to 10thDay
4312323335%70%
1674
11th to 20thDay
3413324336%67%
1710
21st to endDay
5%42442345%6%61%
1710
December1st to 10thDay
7%5%1342445%7%56%
1710
11th to 20thDay
13%8%244345%6%7%42%
2169
21st to endDay
10%10%26%6%34446%47%
3004
January1st to 10thNight
9%5%243235%5%7%55%
2646
11th to 20thNight
6%413323447%62%
2402
21st to endNight
9%7%3432235%5%57%
2376
February1st to 10thNight
6%6%24423345%61%
2160
11th to 20thNight
7%5%25%322345%61%
2098
21st to endNight
7%7%245%34446%54%
1776
March1st to 10thNight
6%8%24435%5%6%8%49%
2160
11th to 20thNight
5%7%2443446%6%55%
2114
21st to endNight
5%6%244245%5%6%58%
1980
April1st to 10thNight
7%424323338%62%
1800
11th to 20thNight
4323323435%70%
1779
21st to endNight
2412323347%70%
1800
May1st to 10thNight
242332335%5%68%
1724
11th to 20thNight
2313213245%74%
1594
21st to endNight
2112212347%76%
1746
June1st to 10thNight
212113337%77%
1609
11th to 20thNight
1111112389%
1440
21st to endNight
11111222287%
1440
July1st to 10thNight
11221221386%
1440
11th to 20thNight
2112312235%77%
1471
21st to endNight
3212213345%74%
1912
August1st to 10thNight
21211223382%
1790
11th to 20thNight
11111123387%
1780
21st to endNight
21121223383%
1980
September1st to 10thNight
311111113384%
1800
11th to 20thNight
111111212288%
1938
21st to endNight
12221132383%
1980
October1st to 10thNight
331331332474%
1980
11th to 20thNight
321221223380%
2082
21st to endNight
131322223476%
2428
November1st to 10thNight
3413313346%70%
2405
11th to 20thNight
25%23313346%68%
2470
21st to endNight
5%5%2443445%6%59%
2470
December1st to 10thNight
7%5%24434347%57%
2470
11th to 20thNight
11%11%25%43445%8%44%
3041
21st to endNight
7%6%26%5%3445%7%49%
4649

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
27%47%17%26%19%
1519
11th to 20thDay
26%37%12%28%24%
1618
21st to endDay
30%47%13%22%24%
1980
February1st to 10thDay
25%36%14%24%28%
1800
11th to 20thDay
25%35%14%29%23%
1760
21st to endDay
29%47%15%24%20%
1480
March1st to 10thDay
34%5%9%16%18%18%
1800
11th to 20thDay
26%6%9%19%24%16%
1839
21st to endDay
26%6%10%21%24%13%
2376
April1st to 10thDay
24%5%10%26%23%12%
2160
11th to 20thDay
19%47%21%30%18%
2132
21st to endDay
18%39%23%35%11%
2160
May1st to 10thDay
20%411%20%31%14%
2236
11th to 20thDay
15%48%24%36%13%
2304
21st to endDay
18%48%27%33%10%
2530
June1st to 10thDay
13%39%18%35%22%
2344
11th to 20thDay
7%25%13%34%38%
2520
21st to endDay
9%236%30%50%
2520
July1st to 10thDay
8%247%25%53%
2451
11th to 20thDay
11%2416%29%37%
2409
21st to endDay
12%48%19%33%25%
2269
August1st to 10thDay
8%2410%29%47%
2135
11th to 20thDay
6%2313%34%43%
2122
21st to endDay
9%249%35%41%
2376
September1st to 10thDay
9%36%7%32%44%
2160
11th to 20thDay
5%1311%36%43%
2021
21st to endDay
10%2413%36%35%
1980
October1st to 10thDay
17%35%16%25%35%
1980
11th to 20thDay
12%2413%29%39%
1873
21st to endDay
13%3412%26%42%
1926
November1st to 10thDay
18%3415%31%29%
1674
11th to 20thDay
19%35%13%23%36%
1710
21st to endDay
24%37%12%24%31%
1710
December1st to 10thDay
26%48%15%23%24%
1710
11th to 20thDay
37%6%8%13%20%15%
2168
21st to endDay
38%47%19%19%13%
3004
January1st to 10thNight
27%46%15%27%21%
2646
11th to 20thNight
22%37%13%27%27%
2402
21st to endNight
28%39%13%20%28%
2376
February1st to 10thNight
25%36%12%24%29%
2160
11th to 20thNight
24%36%13%27%27%
2099
21st to endNight
30%5%6%14%23%23%
1776
March1st to 10thNight
31%49%18%20%18%
2160
11th to 20thNight
25%5%10%15%25%20%
2114
21st to endNight
25%5%8%22%26%14%
1980
April1st to 10thNight
24%49%23%23%18%
1800
11th to 20thNight
18%38%21%27%22%
1779
21st to endNight
16%39%22%35%14%
1800
May1st to 10thNight
18%49%21%29%19%
1724
11th to 20thNight
14%48%22%35%17%
1595
21st to endNight
10%411%24%38%13%
1746
June1st to 10thNight
10%39%18%32%29%
1609
11th to 20thNight
428%13%30%44%
1440
21st to endNight
6%145%26%58%
1440
July1st to 10thNight
6%138%22%61%
1400
11th to 20thNight
11%36%13%26%42%
1423
21st to endNight
12%36%18%30%31%
1806
August1st to 10thNight
7%35%5%27%52%
1780
11th to 20thNight
5%1310%34%46%
1780
21st to endNight
8%138%33%47%
1980
September1st to 10thNight
8%246%28%52%
1800
11th to 20thNight
5%248%36%45%
1938
21st to endNight
8%2312%32%43%
1980
October1st to 10thNight
16%3412%28%37%
1980
11th to 20thNight
11%3412%29%40%
2082
21st to endNight
14%339%24%47%
2428
November1st to 10thNight
17%35%12%31%33%
2405
11th to 20thNight
18%36%12%25%38%
2470
21st to endNight
25%46%15%21%30%
2470
December1st to 10thNight
27%46%13%23%28%
2470
11th to 20thNight
37%6%8%12%21%16%
3041
21st to endNight
32%410%20%22%12%
4649

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
16%19%33%24%42
180
11th to 20thDay
16%20%36%22%6%
300
21st to endDay
14%25%35%20%5%1
462
February1st to 10thDay
15%20%33%25%6%1
420
11th to 20thDay
17%23%37%18%5%1
415
21st to endDay
17%24%37%18%3
346
March1st to 10thDay
19%27%34%16%5%
420
11th to 20thDay
17%21%35%21%5%1
420
21st to endDay
16%27%36%18%3
462
April1st to 10thDay
13%18%39%21%8%
420
11th to 20thDay
6%30%38%20%41
412
21st to endDay
6%25%33%28%7%2
420
May1st to 10thDay
12%17%39%23%6%1
423
11th to 20thDay
6%16%39%28%8%4
448
21st to endDay
9%14%39%28%7%4
485
June1st to 10thDay
314%35%30%14%4
450
11th to 20thDay
19%36%37%11%5%
450
21st to endDay
27%37%38%10%6%
450
July1st to 10thDay
1229%48%15%6%
446
11th to 20thDay
2123%51%14%10%
444
21st to endDay
2125%49%15%8%
487
August1st to 10thDay
2334%41%14%6%
447
11th to 20thDay
2229%46%16%5%
437
21st to endDay
1132%46%14%6%
495
September1st to 10thDay
25%36%40%14%3
450
11th to 20thDay
28%40%38%12%1
450
21st to endDay
213%33%38%12%2
450
October1st to 10thDay
5%14%36%36%8%1
450
11th to 20thDay
312%43%32%9%1
450
21st to endDay
315%34%34%12%2
441
November1st to 10thDay
7%15%31%35%11%1
270
11th to 20thDay
8%14%37%29%10%2
270
21st to endDay
7%19%37%29%8%1
270
December1st to 10thDay
10%16%39%24%10%
270
11th to 20thDay
9%23%29%29%9%2
270
21st to endDay
20%24%33%17%5%2
255
January1st to 10thNight
13%12%32%30%12%2
760
11th to 20thNight
8%13%36%29%13%1
734
21st to endNight
14%14%32%29%10%2
792
February1st to 10thNight
10%11%29%35%14%1
720
11th to 20thNight
10%11%32%29%14%3
704
21st to endNight
12%13%32%27%14%2
592
March1st to 10thNight
10%13%29%33%14%1
720
11th to 20thNight
9%11%23%32%21%5%
720
21st to endNight
9%12%28%32%16%2
792
April1st to 10thNight
8%7%27%37%19%3
720
11th to 20thNight
5%11%27%33%21%2
711
21st to endNight
411%26%34%20%6%
720
May1st to 10thNight
6%6%26%38%20%4
644
11th to 20thNight
37%18%38%31%3
531
21st to endNight
26%22%37%29%4
584
June1st to 10thNight
1314%41%38%3
529
11th to 20thNight
13%40%41%6%
360
21st to endNight
110%38%43%8%
360
July1st to 10thNight
115%28%55%11%
350
11th to 20thNight
3131%55%9%
379
21st to endNight
21334%49%11%
730
August1st to 10thNight
27%36%45%10%
716
11th to 20thNight
1330%53%13%
712
21st to endNight
25%31%49%13%
792
September1st to 10thNight
316%32%46%12%
720
11th to 20thNight
1110%42%36%11%
720
21st to endNight
1219%35%36%7%
720
October1st to 10thNight
4421%44%24%2
720
11th to 20thNight
5%5%21%37%26%6%
720
21st to endNight
311%22%34%21%9%
792
November1st to 10thNight
6%6%26%36%21%4
740
11th to 20thNight
46%33%34%16%6%
760
21st to endNight
8%9%33%32%14%4
760
December1st to 10thNight
9%11%31%35%14%1
760
11th to 20thNight
12%13%31%32%11%1
760
21st to endNight
9%18%34%29%8%2
836
Page generated at 2024-01-11 01:22:41. Version ac07

Copyright 2024 Attilla Danko


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