Cuttin' Edge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cuttin' Edge Observatory clear sky chart from 2005-11-06 to 2024-01-15.

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
70%
24100
35%
74367
28%
24052
77%
24052
52%
35186

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
63%
759
34%
2457
28%
756
74%
756
44%
1209
January11th to 20thNight
63%
736
35%
2392
31%
736
73%
736
47%
1152
January21st to endNight
55%
792
35%
2574
28%
792
67%
792
37%
1369
February1st to 10thNight
61%
720
37%
2264
29%
720
74%
720
50%
1059
February11th to 20thNight
56%
700
34%
2099
26%
700
69%
700
46%
1065
February21st to endNight
55%
592
35%
1776
30%
592
65%
592
46%
908
March1st to 10thNight
57%
720
34%
1997
24%
720
68%
720
49%
1036
March11th to 20thNight
61%
720
35%
1980
26%
720
70%
720
51%
1016
March21st to endNight
61%
792
35%
2178
22%
792
71%
792
54%
1083
April1st to 10thNight
61%
720
33%
1980
18%
720
72%
720
58%
960
April11th to 20thNight
55%
619
38%
1828
21%
619
70%
619
57%
813
April21st to endNight
61%
540
44%
1620
27%
540
76%
540
68%
672
May1st to 10thNight
68%
540
39%
1620
28%
540
76%
540
59%
702
May11th to 20thNight
71%
531
40%
1594
31%
531
77%
531
64%
673
May21st to endNight
73%
582
39%
1746
29%
582
78%
582
73%
691
June1st to 10thNight
80%
540
36%
1620
30%
540
82%
540
71%
661
June11th to 20thNight
79%
540
37%
1620
30%
540
82%
540
76%
633
June21st to endNight
83%
540
33%
1620
30%
540
84%
540
67%
689
July1st to 10thNight
85%
525
28%
1575
24%
525
86%
525
52%
770
July11th to 20thNight
88%
522
25%
1566
21%
522
88%
522
49%
781
July21st to endNight
77%
591
23%
1674
20%
558
79%
558
36%
969
August1st to 10thNight
89%
537
26%
1602
22%
534
89%
534
49%
800
August11th to 20thNight
86%
534
31%
1602
28%
534
86%
534
46%
803
August21st to endNight
85%
712
32%
1980
28%
712
86%
712
49%
1065
September1st to 10thNight
82%
720
31%
1980
28%
720
83%
720
52%
1028
September11th to 20thNight
87%
720
42%
1980
35%
720
90%
720
67%
903
September21st to endNight
78%
720
40%
1980
30%
720
84%
720
66%
906
October1st to 10thNight
73%
720
37%
1998
28%
720
79%
720
57%
986
October11th to 20thNight
79%
720
42%
2160
36%
720
84%
720
68%
901
October21st to endNight
73%
792
44%
2376
35%
792
83%
792
67%
986
November1st to 10thNight
75%
740
41%
2241
35%
740
82%
740
62%
981
November11th to 20thNight
73%
760
40%
2470
36%
760
83%
760
59%
1038
November21st to endNight
65%
760
38%
2470
32%
760
76%
760
48%
1149
December1st to 10thNight
68%
760
35%
2470
33%
760
75%
760
45%
1192
December11th to 20thNight
62%
758
32%
2940
30%
758
71%
758
31%
1564
December21st to endNight
56%
826
22%
4338
28%
817
66%
817
26%
1973

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
331332445%6%65%
74957
Night
3313323446%68%
74857
TransparencyDay
19%5%7%14%28%28%
74684
Night
18%47%14%28%30%
74652
SeeingDay
5%11%26%31%20%7%
13870
Night
4417%37%32%6%
24119

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
5%313424446%63%
1708
11th to 20thDay
4413333445%66%
1656
21st to endDay
7%6%2332446%6%58%
1782
February1st to 10thDay
25%13323347%66%
1694
11th to 20thDay
6%5%24424446%59%
1750
21st to endDay
45%245%23446%61%
1480
March1st to 10thDay
3323435%46%7%61%
1962
11th to 20thDay
45%2432345%6%62%
1980
21st to endDay
322333445%5%66%
2178
April1st to 10thDay
2213423447%68%
1980
11th to 20thDay
2212323346%74%
2076
21st to endDay
121222345%7%72%
2340
May1st to 10thDay
2213323347%71%
2340
11th to 20thDay
2212323446%72%
2301
21st to endDay
231221224477%
2530
June1st to 10thDay
1112223336%78%
2340
11th to 20thDay
11111222386%
2340
21st to endDay
111222334476%
2340
July1st to 10thDay
12135%35%5%6%6%63%
2340
11th to 20thDay
43245%47%8%8%10%45%
2340
21st to endDay
5%436%7%5%7%9%10%12%34%
2545
August1st to 10thDay
33145%36%6%6%8%55%
2328
11th to 20thDay
33145%36%7%9%10%49%
2299
21st to endDay
4314435%6%7%9%52%
2368
September1st to 10thDay
43145%445%6%8%56%
1980
11th to 20thDay
3112222346%74%
1980
21st to endDay
3212322335%73%
1980
October1st to 10thDay
32124235%36%69%
1959
11th to 20thDay
211221123480%
1800
21st to endDay
1112223335%78%
1980
November1st to 10thDay
2222235%45%73%
1836
11th to 20thDay
121222335%6%74%
1710
21st to endDay
6%323323335%68%
1710
December1st to 10thDay
5%6%23335%346%61%
1710
11th to 20thDay
45%25%6%35%47%8%51%
2169
21st to endDay
8%6%36%433346%55%
3146
January1st to 10thNight
33124345%5%7%63%
2457
11th to 20thNight
5%31333335%6%65%
2392
21st to endNight
6%6%24434335%60%
2574
February1st to 10thNight
3313322345%70%
2264
11th to 20thNight
45%23333446%65%
2098
21st to endNight
5%5%1332345%6%64%
1776
March1st to 10thNight
342333435%7%64%
1997
11th to 20thNight
5%423323346%66%
1980
21st to endNight
321242346%7%67%
2178
April1st to 10thNight
311332345%6%70%
1980
11th to 20thNight
1123222345%74%
1828
21st to endNight
1112213345%79%
1620
May1st to 10thNight
211231335%5%74%
1620
11th to 20thNight
2112222235%80%
1594
21st to endNight
221111225%83%
1746
June1st to 10thNight
11122323480%
1620
11th to 20thNight
1121222286%
1620
21st to endNight
111322333478%
1620
July1st to 10thNight
12234245%6%9%63%
1620
11th to 20thNight
12134345%8%9%60%
1620
21st to endNight
3425%5%46%6%9%11%45%
1773
August1st to 10thNight
2212435%5%7%9%61%
1611
11th to 20thNight
22134346%7%12%56%
1602
21st to endNight
2214426%5%6%8%60%
1980
September1st to 10thNight
232343446%10%60%
1980
11th to 20thNight
2112322245%77%
1980
21st to endNight
2212213335%77%
1980
October1st to 10thNight
3213322346%71%
1998
11th to 20thNight
211222132381%
2160
21st to endNight
1212212335%80%
2376
November1st to 10thNight
2212222345%74%
2241
11th to 20thNight
1213213335%76%
2470
21st to endNight
5%312223346%68%
2470
December1st to 10thNight
431332345%6%65%
2470
11th to 20thNight
6%4245%35%5%5%8%54%
3041
21st to endNight
7%5%233345%5%5%59%
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
23%5%5%16%32%18%
1709
11th to 20thDay
23%36%17%32%20%
1656
21st to endDay
27%5%7%14%30%18%
1782
February1st to 10thDay
21%36%14%27%28%
1694
11th to 20thDay
27%4415%25%24%
1760
21st to endDay
23%5%7%15%28%23%
1480
March1st to 10thDay
23%5%5%14%30%24%
1962
11th to 20thDay
22%46%14%32%22%
1980
21st to endDay
20%46%17%38%16%
2178
April1st to 10thDay
17%37%15%34%24%
1980
11th to 20thDay
14%35%12%34%34%
2079
21st to endDay
13%35%13%36%30%
2340
May1st to 10thDay
13%5%6%14%31%32%
2340
11th to 20thDay
12%46%13%31%33%
2304
21st to endDay
11%3310%33%40%
2530
June1st to 10thDay
10%246%34%46%
2340
11th to 20thDay
6%14321%66%
2340
21st to endDay
12%25%6%22%53%
2340
July1st to 10thDay
17%7%7%14%18%37%
2276
11th to 20thDay
26%13%14%18%18%11%
2271
21st to endDay
32%14%16%18%13%8%
2404
August1st to 10thDay
23%8%11%16%19%24%
2313
11th to 20thDay
22%10%12%21%19%17%
2299
21st to endDay
23%9%9%17%26%15%
2368
September1st to 10thDay
22%6%11%14%23%25%
1980
11th to 20thDay
11%37%12%34%33%
1980
21st to endDay
13%46%10%31%36%
1980
October1st to 10thDay
17%5%6%16%22%34%
1959
11th to 20thDay
9%339%32%44%
1800
21st to endDay
11%35%13%32%36%
1980
November1st to 10thDay
13%36%17%35%26%
1836
11th to 20thDay
13%4417%29%33%
1710
21st to endDay
20%35%14%31%26%
1710
December1st to 10thDay
26%5%6%17%23%24%
1710
11th to 20thDay
31%49%19%19%17%
2168
21st to endDay
31%5%6%18%29%12%
3146
January1st to 10thNight
22%5%6%17%33%17%
2457
11th to 20thNight
21%36%17%30%22%
2392
21st to endNight
29%35%12%30%21%
2574
February1st to 10thNight
18%36%15%28%29%
2264
11th to 20thNight
22%36%16%27%25%
2099
21st to endNight
23%36%13%31%24%
1776
March1st to 10thNight
21%46%14%29%26%
1997
11th to 20thNight
21%35%14%31%25%
1980
21st to endNight
17%5%9%16%34%20%
2178
April1st to 10thNight
16%36%14%36%26%
1980
11th to 20thNight
13%35%10%33%36%
1828
21st to endNight
9%36%12%36%35%
1620
May1st to 10thNight
12%45%13%29%37%
1620
11th to 20thNight
11%3410%33%39%
1595
21st to endNight
8%2310%34%43%
1746
June1st to 10thNight
9%235%27%54%
1620
11th to 20thNight
7%23319%67%
1620
21st to endNight
12%246%17%60%
1620
July1st to 10thNight
17%6%8%11%18%40%
1575
11th to 20thNight
17%8%17%18%25%14%
1566
21st to endNight
27%10%18%21%15%10%
1674
August1st to 10thNight
17%9%13%15%19%27%
1602
11th to 20thNight
18%9%15%21%17%20%
1602
21st to endNight
21%6%9%20%26%18%
1980
September1st to 10thNight
19%6%13%18%19%25%
1980
11th to 20thNight
11%46%12%30%37%
1980
21st to endNight
12%35%10%31%40%
1980
October1st to 10thNight
17%36%16%22%36%
1998
11th to 20thNight
10%249%28%47%
2160
21st to endNight
10%36%11%27%44%
2376
November1st to 10thNight
14%25%15%36%28%
2241
11th to 20thNight
13%35%14%30%36%
2470
21st to endNight
19%4414%30%30%
2470
December1st to 10thNight
20%5%7%17%24%27%
2470
11th to 20thNight
29%5%7%15%25%18%
3041
21st to endNight
27%410%17%25%16%
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
13%11%24%33%18%
270
11th to 20thDay
13%7%29%33%15%3
252
21st to endDay
416%30%25%20%5%
264
February1st to 10thDay
415%31%29%18%3
314
11th to 20thDay
11%21%32%27%10%
415
21st to endDay
11%26%31%24%7%1
346
March1st to 10thDay
9%24%34%22%10%1
420
11th to 20thDay
8%19%30%26%13%4
420
21st to endDay
8%25%36%19%11%1
462
April1st to 10thDay
6%16%35%25%15%4
420
11th to 20thDay
7%23%39%17%10%3
412
21st to endDay
423%33%25%10%5%
420
May1st to 10thDay
417%39%24%13%3
423
11th to 20thDay
215%36%25%16%6%
448
21st to endDay
5%15%33%28%15%4
485
June1st to 10thDay
110%32%35%18%5%
450
11th to 20thDay
210%33%32%16%7%
450
21st to endDay
15%27%40%21%6%
450
July1st to 10thDay
221%42%25%10%
446
11th to 20thDay
3110%41%28%17%
444
21st to endDay
5%8%34%34%19%
487
August1st to 10thDay
2113%40%29%15%
447
11th to 20thDay
2212%38%32%14%
437
21st to endDay
3110%36%34%17%
495
September1st to 10thDay
4218%36%28%12%
450
11th to 20thDay
3325%35%27%7%
450
21st to endDay
5%7%22%36%22%8%
450
October1st to 10thDay
312%28%27%24%7%
429
11th to 20thDay
45%22%30%31%7%
270
21st to endDay
311%17%35%27%7%
297
November1st to 10thDay
6%8%21%36%25%4
270
11th to 20thDay
39%20%36%25%7%
270
21st to endDay
9%10%24%33%20%4
270
December1st to 10thDay
8%11%19%35%26%1
270
11th to 20thDay
111%29%38%18%3
270
21st to endDay
14%16%22%31%15%2
297
January1st to 10thNight
6%5%21%43%19%6%
760
11th to 20thNight
6%423%38%24%5%
736
21st to endNight
8%8%24%38%20%3
792
February1st to 10thNight
46%23%40%23%3
720
11th to 20thNight
6%8%25%42%17%2
704
21st to endNight
9%7%26%39%17%3
592
March1st to 10thNight
6%7%28%42%16%2
720
11th to 20thNight
7%6%21%33%28%4
720
21st to endNight
48%24%41%21%2
792
April1st to 10thNight
4426%43%20%3
720
11th to 20thNight
210%29%34%23%2
619
21st to endNight
16%30%37%23%3
540
May1st to 10thNight
25%21%44%25%2
540
11th to 20thNight
25%19%39%32%3
531
21st to endNight
2319%43%28%4
584
June1st to 10thNight
1213%45%36%2
540
11th to 20thNight
1116%44%33%5%
540
21st to endNight
2110%37%45%5%
540
July1st to 10thNight
25%36%50%7%
525
11th to 20thNight
2222%57%16%
522
21st to endNight
31419%58%15%
591
August1st to 10thNight
2320%60%15%
537
11th to 20thNight
2323%60%12%
534
21st to endNight
21319%56%19%
712
September1st to 10thNight
226%27%50%13%
720
11th to 20thNight
26%34%50%7%
720
21st to endNight
2215%32%42%8%
720
October1st to 10thNight
4314%41%34%3
720
11th to 20thNight
2214%45%33%5%
720
21st to endNight
2417%35%32%10%
792
November1st to 10thNight
3315%43%31%5%
740
11th to 20thNight
3319%39%29%7%
760
21st to endNight
6%5%20%39%26%4
760
December1st to 10thNight
6%6%17%40%29%2
760
11th to 20thNight
9%5%17%44%23%2
760
21st to endNight
8%6%22%44%17%3
836
Page generated at 2024-01-11 20:33:52. Version ac07

Copyright 2024 Attilla Danko


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