Blue Canyon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blue Canyon 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
54%
23376
28%
74709
21%
23329
63%
23329
35%
41081

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
36%
758
18%
2646
13%
756
45%
756
21%
1674
January11th to 20thNight
34%
738
23%
2489
12%
738
49%
738
23%
1520
January21st to endNight
36%
792
27%
2574
16%
792
51%
792
22%
1594
February1st to 10thNight
35%
720
25%
2340
14%
720
50%
720
25%
1389
February11th to 20thNight
40%
700
25%
2144
17%
700
53%
700
25%
1327
February21st to endNight
37%
592
25%
1776
17%
592
49%
592
25%
1129
March1st to 10thNight
34%
720
15%
2135
9%
720
42%
720
18%
1511
March11th to 20thNight
43%
720
21%
1980
14%
720
51%
720
26%
1309
March21st to endNight
37%
792
17%
2073
7%
792
44%
792
24%
1440
April1st to 10thNight
42%
720
21%
1800
8%
720
49%
720
29%
1222
April11th to 20thNight
46%
711
24%
1779
9%
711
52%
711
33%
1138
April21st to endNight
56%
720
25%
1800
10%
720
62%
720
43%
1055
May1st to 10thNight
49%
641
26%
1721
13%
641
57%
641
40%
973
May11th to 20thNight
64%
354
29%
1416
28%
354
71%
354
36%
652
May21st to endNight
63%
388
24%
1552
25%
388
70%
388
35%
749
June1st to 10thNight
68%
360
25%
1440
30%
360
74%
360
37%
653
June11th to 20thNight
71%
360
35%
1440
40%
360
81%
360
56%
522
June21st to endNight
76%
360
34%
1440
40%
360
85%
360
58%
514
July1st to 10thNight
84%
350
37%
1400
47%
350
88%
350
73%
437
July11th to 20thNight
85%
348
39%
1392
48%
348
88%
348
72%
437
July21st to endNight
80%
514
40%
1602
36%
486
84%
486
64%
643
August1st to 10thNight
78%
537
37%
1602
29%
534
82%
534
63%
713
August11th to 20thNight
82%
687
39%
1755
23%
687
85%
687
76%
802
August21st to endNight
84%
792
42%
1980
24%
792
87%
792
77%
914
September1st to 10thNight
82%
720
45%
1800
27%
720
87%
720
80%
814
September11th to 20thNight
77%
720
44%
1800
31%
720
82%
720
69%
880
September21st to endNight
67%
720
41%
1998
30%
720
79%
720
61%
935
October1st to 10thNight
63%
720
32%
2160
28%
720
72%
720
50%
1041
October11th to 20thNight
62%
720
38%
2160
33%
720
74%
720
51%
1024
October21st to endNight
58%
792
38%
2376
29%
792
72%
792
48%
1166
November1st to 10thNight
53%
740
28%
2405
23%
740
63%
740
33%
1343
November11th to 20thNight
49%
760
28%
2470
19%
760
62%
760
34%
1330
November21st to endNight
43%
760
26%
2587
20%
760
55%
760
30%
1437
December1st to 10thNight
39%
760
24%
2660
16%
760
53%
760
24%
1546
December11th to 20thNight
34%
760
20%
3226
13%
759
47%
759
14%
2244
December21st to endNight
29%
830
15%
4791
13%
817
43%
817
10%
3004

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
10%6%23323345%60%
74772
Night
12%7%23323345%57%
75021
TransparencyDay
28%37%18%25%19%
74483
Night
31%37%18%23%18%
74831
SeeingDay
16%14%32%26%10%3
13966
Night
16%6%19%33%22%4
23389

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
21%11%25%423347%38%
1519
11th to 20thDay
17%8%23324345%48%
1562
21st to endDay
15%13%23423447%42%
1782
February1st to 10thDay
19%10%22223346%47%
1620
11th to 20thDay
15%13%3332345%5%45%
1703
21st to endDay
17%16%4421234443%
1480
March1st to 10thDay
18%16%445%3345%6%32%
1822
11th to 20thDay
20%12%34323446%39%
1980
21st to endDay
19%14%2332435%6%38%
2282
April1st to 10thDay
17%11%24423447%41%
2160
11th to 20thDay
15%9%23424445%49%
2129
21st to endDay
13%6%13313346%55%
2160
May1st to 10thDay
10%6%13323447%59%
2233
11th to 20thDay
9%5%23322447%57%
2477
21st to endDay
13%5%24323447%53%
2723
June1st to 10thDay
9%42442445%7%58%
2520
11th to 20thDay
4212212335%76%
2520
21st to endDay
311211122481%
2520
July1st to 10thDay
11111222386%
2520
11th to 20thDay
21111122386%
2520
21st to endDay
121232222381%
2617
August1st to 10thDay
311221224479%
2328
11th to 20thDay
11121122484%
2145
21st to endDay
11111122290%
2376
September1st to 10thDay
2111122385%
2160
11th to 20thDay
5%212212335%74%
2160
21st to endDay
5%31221223475%
1956
October1st to 10thDay
8%313323345%68%
1800
11th to 20thDay
7%31332235%6%66%
1800
21st to endDay
10%41332333464%
1980
November1st to 10thDay
14%8%23413346%51%
1674
11th to 20thDay
14%5%14424447%51%
1710
21st to endDay
11%9%2432445%6%51%
1592
December1st to 10thDay
19%6%2331345%7%45%
1520
11th to 20thDay
27%12%35%423346%31%
1928
21st to endDay
14%9%25%5%25%5%6%8%39%
2794
January1st to 10thNight
18%12%2432445%6%41%
2646
11th to 20thNight
16%8%2442445%8%44%
2489
21st to endNight
16%12%23323446%45%
2574
February1st to 10thNight
17%7%34323346%49%
2340
11th to 20thNight
13%12%2432445%6%45%
2144
21st to endNight
16%12%35%223336%45%
1776
March1st to 10thNight
21%15%44423445%36%
2135
11th to 20thNight
18%12%23324447%41%
1980
21st to endNight
16%14%2332444442%
2073
April1st to 10thNight
16%11%3432335%6%44%
1800
11th to 20thNight
13%8%23324446%50%
1779
21st to endNight
10%6%13224446%59%
1800
May1st to 10thNight
10%6%2342334460%
1721
11th to 20thNight
9%31432445%8%58%
1416
21st to endNight
10%41342335%7%58%
1552
June1st to 10thNight
8%412223447%63%
1440
11th to 20thNight
3212112245%77%
1440
21st to endNight
321222223379%
1440
July1st to 10thNight
11112232385%
1440
11th to 20thNight
111211212485%
1440
21st to endNight
221321224378%
1696
August1st to 10thNight
321322323475%
1611
11th to 20thNight
111122224481%
1755
21st to endNight
111121222384%
1980
September1st to 10thNight
2111222485%
1800
11th to 20thNight
321221223478%
1800
21st to endNight
3312222345%75%
1998
October1st to 10thNight
7%31332332371%
2160
11th to 20thNight
7%212222245%70%
2160
21st to endNight
10%31221235%5%67%
2376
November1st to 10thNight
15%7%23313336%54%
2405
11th to 20thNight
12%41332345%7%54%
2470
21st to endNight
12%7%24324445%54%
2587
December1st to 10thNight
20%7%12323335%50%
2660
11th to 20thNight
29%10%23323447%32%
3276
21st to endNight
17%11%35%5%35%447%36%
4862

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
49%38%21%15%4
1519
11th to 20thDay
40%37%19%18%13%
1562
21st to endDay
43%48%14%24%8%
1782
February1st to 10thDay
40%210%18%19%11%
1620
11th to 20thDay
41%38%17%22%8%
1713
21st to endDay
46%36%22%15%8%
1480
March1st to 10thDay
53%48%14%16%5%
1822
11th to 20thDay
47%39%18%16%6%
1980
21st to endDay
48%413%18%13%3
2282
April1st to 10thDay
44%5%12%20%16%3
2160
11th to 20thDay
36%412%23%18%6%
2132
21st to endDay
30%314%27%21%4
2160
May1st to 10thDay
27%410%28%24%7%
2233
11th to 20thDay
27%311%28%24%7%
2480
21st to endDay
31%413%28%19%5%
2724
June1st to 10thDay
26%312%22%27%10%
2520
11th to 20thDay
13%38%22%35%20%
2520
21st to endDay
10%1217%38%32%
2520
July1st to 10thDay
6%2210%28%51%
2451
11th to 20thDay
7%2213%28%47%
2445
21st to endDay
11%229%26%50%
2471
August1st to 10thDay
11%2213%29%43%
2312
11th to 20thDay
7%1212%37%42%
2145
21st to endDay
5%1112%38%41%
2376
September1st to 10thDay
7%129%32%49%
2160
11th to 20thDay
15%3420%37%21%
2160
21st to endDay
15%15%20%34%24%
1956
October1st to 10thDay
21%36%19%30%22%
1800
11th to 20thDay
20%37%19%27%24%
1800
21st to endDay
25%27%18%26%21%
1980
November1st to 10thDay
35%38%19%22%14%
1674
11th to 20thDay
34%49%18%24%11%
1710
21st to endDay
34%47%20%23%13%
1592
December1st to 10thDay
39%47%20%19%11%
1520
11th to 20thDay
57%36%14%14%7%
1928
21st to endDay
44%312%22%14%5%
2794
January1st to 10thNight
44%410%21%15%6%
2646
11th to 20thNight
40%48%15%19%13%
2489
21st to endNight
42%36%15%22%12%
2574
February1st to 10thNight
39%36%19%20%13%
2340
11th to 20thNight
40%37%20%21%9%
2145
21st to endNight
42%37%22%19%7%
1776
March1st to 10thNight
52%49%16%14%5%
2135
11th to 20thNight
44%38%21%17%8%
1980
21st to endNight
45%5%11%21%14%5%
2073
April1st to 10thNight
42%5%12%20%16%5%
1800
11th to 20thNight
36%5%13%22%19%6%
1779
21st to endNight
27%413%32%20%4
1800
May1st to 10thNight
28%311%24%27%7%
1721
11th to 20thNight
25%314%28%21%8%
1416
21st to endNight
26%5%16%29%20%4
1552
June1st to 10thNight
23%5%12%24%24%12%
1440
11th to 20thNight
11%47%24%33%21%
1440
21st to endNight
13%1414%34%34%
1440
July1st to 10thNight
6%2211%28%51%
1400
11th to 20thNight
7%2312%23%53%
1392
21st to endNight
12%238%24%51%
1602
August1st to 10thNight
14%2312%26%43%
1602
11th to 20thNight
9%2211%32%44%
1755
21st to endNight
9%2212%29%48%
1980
September1st to 10thNight
8%138%30%51%
1800
11th to 20thNight
13%25%19%40%21%
1800
21st to endNight
14%2420%33%26%
1998
October1st to 10thNight
20%36%18%29%25%
2160
11th to 20thNight
19%2418%32%25%
2160
21st to endNight
20%36%21%28%22%
2376
November1st to 10thNight
33%38%19%21%16%
2405
11th to 20thNight
30%311%19%25%12%
2470
21st to endNight
33%37%19%23%15%
2587
December1st to 10thNight
38%48%18%19%14%
2660
11th to 20thNight
54%36%12%18%7%
3276
21st to endNight
50%310%16%15%6%
4862

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
43%12%20%17%7%
180
11th to 20thDay
29%9%28%21%10%2
258
21st to endDay
27%15%20%26%10%2
374
February1st to 10thDay
31%14%26%21%8%1
340
11th to 20thDay
27%19%30%19%41
395
21st to endDay
30%17%32%18%3
346
March1st to 10thDay
38%20%25%13%41
420
11th to 20thDay
33%17%25%16%9%1
420
21st to endDay
32%19%29%15%4
462
April1st to 10thDay
26%23%29%17%41
420
11th to 20thDay
27%22%29%17%41
412
21st to endDay
17%20%31%22%8%1
420
May1st to 10thDay
17%22%30%21%7%2
423
11th to 20thDay
19%19%31%20%8%3
448
21st to endDay
16%14%30%24%10%5%
485
June1st to 10thDay
10%16%32%26%9%6%
450
11th to 20thDay
10%18%35%24%10%4
450
21st to endDay
314%37%29%11%6%
450
July1st to 10thDay
17%47%28%11%6%
446
11th to 20thDay
17%41%33%11%7%
444
21st to endDay
17%41%33%13%5%
487
August1st to 10thDay
49%37%34%11%4
447
11th to 20thDay
210%36%35%12%4
437
21st to endDay
17%43%37%10%2
495
September1st to 10thDay
48%44%30%14%2
450
11th to 20thDay
7%13%33%34%10%3
450
21st to endDay
7%12%38%33%8%1
450
October1st to 10thDay
7%19%32%31%10%2
450
11th to 20thDay
9%13%28%34%13%3
450
21st to endDay
14%14%27%30%12%3
495
November1st to 10thDay
22%9%21%27%18%4
270
11th to 20thDay
15%11%23%33%16%2
270
21st to endDay
18%12%25%28%16%1
214
December1st to 10thDay
27%13%22%19%15%4
180
11th to 20thDay
26%14%24%20%13%3
180
21st to endDay
28%12%25%22%12%1
198
January1st to 10thNight
28%6%24%24%13%4
760
11th to 20thNight
22%12%26%29%10%1
738
21st to endNight
24%12%22%23%17%2
792
February1st to 10thNight
23%10%26%27%13%1
720
11th to 20thNight
23%10%20%29%15%3
704
21st to endNight
25%11%23%30%9%2
592
March1st to 10thNight
30%9%20%26%12%2
720
11th to 20thNight
26%8%17%26%22%1
720
21st to endNight
27%8%23%27%13%2
792
April1st to 10thNight
22%6%22%33%15%2
720
11th to 20thNight
19%9%21%32%15%3
711
21st to endNight
14%6%19%35%21%4
720
May1st to 10thNight
12%10%23%32%21%3
641
11th to 20thNight
10%6%15%39%27%3
354
21st to endNight
13%414%33%31%5%
389
June1st to 10thNight
9%413%38%33%4
360
11th to 20thNight
35%18%38%34%3
360
21st to endNight
3214%42%34%5%
360
July1st to 10thNight
111%37%47%4
350
11th to 20thNight
12%44%38%5%
348
21st to endNight
2111%30%48%9%
514
August1st to 10thNight
3113%39%37%7%
537
11th to 20thNight
2113%40%36%9%
687
21st to endNight
210%45%38%4
792
September1st to 10thNight
2112%44%36%5%
720
11th to 20thNight
4213%38%33%9%
720
21st to endNight
5%5%19%37%25%9%
720
October1st to 10thNight
8%5%19%40%24%5%
720
11th to 20thNight
10%6%18%36%25%5%
720
21st to endNight
12%7%20%32%23%6%
792
November1st to 10thNight
19%5%17%31%22%5%
740
11th to 20thNight
13%10%23%34%17%3
760
21st to endNight
16%8%26%29%17%3
760
December1st to 10thNight
24%11%22%30%11%3
760
11th to 20thNight
30%8%23%26%11%2
760
21st to endNight
29%11%24%25%10%
836
Page generated at 2024-01-12 04:31:49. Version ac07

Copyright 2024 Attilla Danko


Blue Canyon Clear Sky Chart |Charts Home