Coal Creek Crest
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coal Creek Crest clear sky chart from 2005-11-06 to 2024-02-25.

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
41%
22658
10%
80160
11%
22564
43%
22564
14%
60394

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
25%
756
4%
4404
7%
736
27%
736
4%
3933
January11th to 20thNight
30%
754
9%
4363
8%
740
31%
740
5%
3477
January21st to endNight
34%
835
6%
4631
11%
814
35%
814
5%
3991
February1st to 10thNight
30%
760
6%
2470
6%
760
31%
760
8%
2107
February11th to 20thNight
32%
740
8%
2404
7%
740
34%
740
10%
1951
February21st to endNight
31%
610
8%
1932
7%
610
32%
610
9%
1595
March1st to 10thNight
29%
720
7%
2066
6%
720
30%
720
12%
1705
March11th to 20thNight
30%
720
9%
1980
7%
720
33%
720
11%
1633
March21st to endNight
27%
792
5%
2139
3%
792
27%
792
8%
1856
April1st to 10thNight
28%
720
5%
1800
2%
720
29%
720
12%
1525
April11th to 20thNight
34%
681
10%
1749
5%
681
36%
681
15%
1404
April21st to endNight
40%
540
8%
1620
6%
540
42%
540
14%
1228
May1st to 10thNight
43%
392
12%
1472
11%
392
49%
392
18%
975
May11th to 20thNight
51%
354
11%
1416
15%
354
54%
354
16%
981
May21st to endNight
47%
389
8%
1552
10%
388
51%
388
14%
1102
June1st to 10thNight
48%
360
7%
1440
10%
360
49%
360
16%
955
June11th to 20thNight
48%
360
7%
1300
8%
360
50%
360
16%
917
June21st to endNight
60%
360
15%
1260
17%
360
65%
360
33%
696
July1st to 10thNight
67%
350
15%
1229
19%
350
70%
350
37%
637
July11th to 20thNight
68%
348
20%
1392
29%
348
74%
348
37%
663
July21st to endNight
80%
394
26%
1488
38%
372
85%
372
52%
585
August1st to 10thNight
75%
494
20%
1560
20%
492
78%
492
46%
770
August11th to 20thNight
76%
534
27%
1602
23%
534
78%
534
48%
795
August21st to endNight
61%
693
25%
1881
17%
693
64%
693
39%
1099
September1st to 10thNight
63%
720
24%
1800
14%
720
66%
720
45%
1064
September11th to 20thNight
56%
720
20%
1808
12%
720
58%
720
29%
1234
September21st to endNight
53%
720
18%
2060
16%
720
55%
720
29%
1324
October1st to 10thNight
50%
720
14%
2160
14%
720
52%
720
24%
1445
October11th to 20thNight
49%
720
16%
2160
16%
720
51%
720
21%
1536
October21st to endNight
37%
792
14%
2420
12%
792
40%
792
16%
1779
November1st to 10thNight
32%
740
8%
2540
8%
740
33%
740
10%
2055
November11th to 20thNight
27%
760
7%
2660
6%
760
30%
760
8%
2192
November21st to endNight
34%
760
7%
2660
7%
760
35%
760
10%
2102
December1st to 10thNight
34%
760
9%
2660
9%
760
35%
760
10%
2147
December11th to 20thNight
26%
759
7%
3235
6%
759
27%
759
5%
2724
December21st to endNight
17%
831
3%
4847
5%
817
18%
817
3%
4212

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
25%11%47%6%3445%6%27%
78831
Night
25%11%36%5%34446%28%
80422
TransparencyDay
58%7%11%15%8%1
78553
Night
57%7%11%15%8%2
80280
SeeingDay
23%12%25%26%12%2
14066
Night
26%7%17%32%17%1
22679

By Month

Percentage Cloud Cover NW (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
40%19%47%6%343348%
2539
11th to 20thDay
36%14%46%423335%18%
2516
21st to endDay
44%14%47%5%3333311%
3025
February1st to 10thDay
34%15%47%5%35%446%13%
1710
11th to 20thDay
30%16%5%9%6%3444416%
1665
21st to endDay
31%17%48%6%2444416%
1418
March1st to 10thDay
33%14%48%7%25%445%14%
1891
11th to 20thDay
36%15%47%5%23345%16%
1980
21st to endDay
32%15%5%10%7%47%4449%
2216
April1st to 10thDay
30%14%5%8%6%35%45%6%14%
2160
11th to 20thDay
30%13%48%5%4445%5%19%
2158
21st to endDay
24%13%48%7%35%446%21%
2340
May1st to 10thDay
19%10%37%6%35%5%6%6%30%
2488
11th to 20thDay
21%9%48%7%35%6%6%7%24%
2477
21st to endDay
23%9%38%7%46%5%6%6%22%
2723
June1st to 10thDay
24%10%47%6%445%5%6%25%
2520
11th to 20thDay
23%9%5%9%7%45%5%6%7%20%
2654
21st to endDay
13%7%36%6%36%5%5%7%39%
2700
July1st to 10thDay
9%6%26%5%3445%8%48%
2693
11th to 20thDay
10%5%246%3445%7%49%
2520
21st to endDay
7%5%23323347%58%
2741
August1st to 10thDay
8%6%26%43445%8%50%
2368
11th to 20thDay
8%4233345%5%8%54%
2298
21st to endDay
11%7%36%5%4446%8%43%
2474
September1st to 10thDay
9%6%25%4235%6%9%49%
2160
11th to 20thDay
13%9%46%5%45%46%8%37%
2150
21st to endDay
20%7%36%5%34447%37%
1900
October1st to 10thDay
25%9%36%5%34445%33%
1800
11th to 20thDay
25%7%36%5%35%5%6%7%26%
1800
21st to endDay
33%9%37%5%33445%24%
1934
November1st to 10thDay
35%13%5%8%5%45%5%4413%
1534
11th to 20thDay
38%12%46%5%3435%5%16%
1520
21st to endDay
33%12%39%5%45%34419%
1520
December1st to 10thDay
32%12%5%8%5%3444419%
1520
11th to 20thDay
36%14%48%7%3445%5%11%
1925
21st to endDay
35%17%410%7%35%4349%
2794
January1st to 10thNight
36%17%49%7%3433410%
4406
11th to 20thNight
34%13%47%5%34435%19%
4382
21st to endNight
45%14%46%42333413%
4636
February1st to 10thNight
31%14%5%7%6%45%445%17%
2470
11th to 20thNight
28%13%48%6%34335%22%
2402
21st to endNight
28%16%47%6%345%4420%
1932
March1st to 10thNight
30%12%47%7%3434422%
2066
11th to 20thNight
30%13%46%6%35%445%20%
1979
21st to endNight
32%14%5%7%6%4445%415%
2139
April1st to 10thNight
25%15%5%7%7%45%435%20%
1800
11th to 20thNight
23%13%47%5%35%45%7%25%
1749
21st to endNight
22%11%36%6%345%5%8%27%
1620
May1st to 10thNight
17%11%36%5%34448%36%
1472
11th to 20thNight
17%8%26%6%446%8%8%30%
1416
21st to endNight
14%7%47%7%5%5%5%7%7%33%
1552
June1st to 10thNight
17%6%38%7%445%47%36%
1440
11th to 20thNight
18%8%36%5%345%6%8%33%
1300
21st to endNight
9%7%2443345%7%53%
1260
July1st to 10thNight
5%425%425%5%5%9%55%
1264
11th to 20thNight
5%426%324447%59%
1440
21st to endNight
4312213348%69%
1576
August1st to 10thNight
431343345%10%60%
1568
11th to 20thNight
5%313324447%65%
1602
21st to endNight
9%6%245%24447%53%
1881
September1st to 10thNight
8%413423448%60%
1800
11th to 20thNight
13%6%36%5%2445%7%46%
1808
21st to endNight
14%6%35%43445%8%44%
2060
October1st to 10thNight
20%7%35%423446%41%
2160
11th to 20thNight
21%7%36%5%33446%36%
2160
21st to endNight
28%8%36%5%2435%6%32%
2420
November1st to 10thNight
35%11%36%5%34445%21%
2540
11th to 20thNight
36%10%46%6%3344419%
2660
21st to endNight
29%12%46%6%35%34424%
2660
December1st to 10thNight
31%13%46%5%3444422%
2660
11th to 20thNight
33%15%48%6%3443416%
3280
21st to endNight
33%17%5%9%7%3433311%
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
82%6%6%43
2539
11th to 20thDay
69%6%9%10%42
2540
21st to endDay
78%5%6%7%4
3025
February1st to 10thDay
71%7%11%8%3
1710
11th to 20thDay
73%6%8%9%5%1
1674
21st to endDay
72%410%8%5%1
1418
March1st to 10thDay
71%6%10%8%5%
1891
11th to 20thDay
72%48%12%31
1980
21st to endDay
78%7%7%8%
2216
April1st to 10thDay
70%8%10%11%1
2160
11th to 20thDay
67%6%9%10%7%1
2158
21st to endDay
65%6%11%12%6%1
2340
May1st to 10thDay
53%8%14%18%6%
2488
11th to 20thDay
58%8%15%14%5%1
2480
21st to endDay
61%9%13%14%2
2724
June1st to 10thDay
60%7%16%12%6%
2520
11th to 20thDay
61%9%16%11%3
2654
21st to endDay
42%9%16%22%9%2
2700
July1st to 10thDay
37%7%13%23%16%4
2619
11th to 20thDay
33%6%11%26%20%3
2445
21st to endDay
24%411%32%25%4
2589
August1st to 10thDay
32%7%15%25%17%3
2351
11th to 20thDay
26%7%15%29%17%5%
2298
21st to endDay
38%7%12%29%13%2
2474
September1st to 10thDay
32%7%14%24%17%6%
2160
11th to 20thDay
45%8%12%15%16%4
2150
21st to endDay
46%7%14%15%15%3
1900
October1st to 10thDay
54%6%8%20%10%2
1800
11th to 20thDay
55%7%14%13%10%1
1800
21st to endDay
63%5%8%14%11%
1934
November1st to 10thDay
72%7%7%10%3
1534
11th to 20thDay
69%6%10%7%5%2
1520
21st to endDay
69%5%6%8%12%
1520
December1st to 10thDay
70%5%6%10%8%1
1520
11th to 20thDay
72%9%8%9%2
1928
21st to endDay
77%7%8%5%3
2794
January1st to 10thNight
79%7%7%421
4406
11th to 20thNight
67%7%8%13%32
4420
21st to endNight
76%5%7%7%41
4636
February1st to 10thNight
71%7%8%11%21
2470
11th to 20thNight
65%7%11%9%6%2
2404
21st to endNight
69%6%11%8%6%
1932
March1st to 10thNight
66%7%11%12%4
2066
11th to 20thNight
65%7%10%12%5%1
1980
21st to endNight
71%8%11%9%1
2139
April1st to 10thNight
68%7%12%11%3
1800
11th to 20thNight
59%9%10%13%6%2
1749
21st to endNight
57%8%15%14%5%1
1620
May1st to 10thNight
46%8%17%20%8%1
1472
11th to 20thNight
50%9%17%18%5%2
1416
21st to endNight
49%12%17%17%5%
1552
June1st to 10thNight
49%6%18%22%4
1440
11th to 20thNight
48%11%21%18%3
1300
21st to endNight
30%7%23%28%9%3
1260
July1st to 10thNight
25%7%19%27%16%5%
1229
11th to 20thNight
24%6%14%32%21%4
1392
21st to endNight
13%5%14%38%21%8%
1488
August1st to 10thNight
19%7%20%31%17%5%
1560
11th to 20thNight
18%7%17%35%15%7%
1602
21st to endNight
29%6%14%33%15%2
1881
September1st to 10thNight
26%6%14%28%18%8%
1800
11th to 20thNight
41%7%12%20%14%7%
1808
21st to endNight
38%7%16%19%16%3
2060
October1st to 10thNight
44%6%11%24%13%2
2160
11th to 20thNight
50%6%12%19%11%2
2160
21st to endNight
56%5%10%16%12%
2420
November1st to 10thNight
66%7%10%12%5%
2540
11th to 20thNight
68%7%8%9%5%3
2660
21st to endNight
64%7%8%9%11%1
2660
December1st to 10thNight
65%7%7%12%7%1
2660
11th to 20thNight
71%7%8%9%4
3276
21st to endNight
76%8%8%6%2
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
41%14%21%14%7%3
180
11th to 20thDay
36%14%26%14%8%2
180
21st to endDay
37%12%17%24%9%2
338
February1st to 10thDay
42%12%19%16%11%1
370
11th to 20thDay
40%15%23%16%5%1
365
21st to endDay
36%17%23%17%7%
315
March1st to 10thDay
32%18%26%17%6%1
420
11th to 20thDay
30%15%26%19%9%2
420
21st to endDay
35%17%23%16%8%1
462
April1st to 10thDay
32%16%22%20%7%3
420
11th to 20thDay
29%22%24%16%7%3
412
21st to endDay
26%15%29%21%7%2
420
May1st to 10thDay
19%15%27%25%10%3
423
11th to 20thDay
28%12%24%22%11%2
448
21st to endDay
21%12%26%28%11%2
485
June1st to 10thDay
25%10%24%28%11%2
450
11th to 20thDay
19%18%33%23%7%1
584
21st to endDay
10%12%31%31%13%2
630
July1st to 10thDay
10%7%30%37%14%2
614
11th to 20thDay
9%9%24%38%16%3
444
21st to endDay
6%425%42%22%2
487
August1st to 10thDay
9%5%21%43%17%5%
447
11th to 20thDay
4322%42%24%5%
437
21st to endDay
10%7%32%35%13%4
495
September1st to 10thDay
10%8%29%38%13%2
450
11th to 20thDay
14%9%23%36%16%3
450
21st to endDay
19%14%22%30%14%2
450
October1st to 10thDay
24%11%24%26%12%2
450
11th to 20thDay
25%10%21%24%16%3
450
21st to endDay
31%13%25%17%12%2
449
November1st to 10thDay
28%18%27%19%7%1
203
11th to 20thDay
38%11%18%22%10%2
180
21st to endDay
29%20%21%14%15%1
180
December1st to 10thDay
34%12%23%16%13%2
180
11th to 20thDay
37%19%23%13%8%1
180
21st to endDay
40%14%21%18%7%1
198
January1st to 10thNight
42%9%16%19%12%2
760
11th to 20thNight
38%9%14%23%15%1
760
21st to endNight
34%7%14%27%16%2
836
February1st to 10thNight
35%8%15%29%13%1
760
11th to 20thNight
30%9%17%30%14%1
744
21st to endNight
32%11%16%29%12%
610
March1st to 10thNight
31%9%20%24%14%1
720
11th to 20thNight
31%10%18%28%13%1
720
21st to endNight
35%9%17%27%12%1
792
April1st to 10thNight
31%9%20%25%15%1
720
11th to 20thNight
25%9%21%30%13%2
681
21st to endNight
26%5%17%35%15%1
540
May1st to 10thNight
20%7%22%32%19%1
392
11th to 20thNight
18%5%16%36%22%2
354
21st to endNight
15%5%18%37%23%1
389
June1st to 10thNight
18%318%42%19%
360
11th to 20thNight
18%6%20%41%14%1
360
21st to endNight
11%222%47%19%
360
July1st to 10thNight
5%216%52%24%
350
11th to 20thNight
5%218%54%20%1
348
21st to endNight
3211%60%24%1
394
August1st to 10thNight
5%210%47%32%3
494
11th to 20thNight
6%210%44%37%3
534
21st to endNight
11%316%44%25%2
693
September1st to 10thNight
10%318%42%25%2
720
11th to 20thNight
13%315%34%31%3
720
21st to endNight
15%6%17%39%21%2
720
October1st to 10thNight
21%415%36%21%2
720
11th to 20thNight
24%5%15%29%24%3
720
21st to endNight
29%7%18%27%18%1
792
November1st to 10thNight
33%9%18%29%10%
740
11th to 20thNight
38%9%16%22%13%1
760
21st to endNight
32%8%18%25%16%2
760
December1st to 10thNight
31%7%17%27%15%2
760
11th to 20thNight
37%8%18%24%11%1
760
21st to endNight
42%11%19%19%7%1
836
Page generated at 2024-02-22 03:05:46. Version ac07

Copyright 2024 Attilla Danko


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