Quail Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Quail Creek Observatory clear sky chart from 2005-11-06 to 2024-01-31.

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
49%
24098
29%
74470
20%
24042
58%
24042
38%
40588

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
38%
948
32%
2458
13%
946
49%
946
43%
1420
January11th to 20thNight
36%
950
30%
2470
11%
950
47%
950
38%
1454
January21st to endNight
35%
1043
32%
2711
12%
1043
47%
1043
37%
1631
February1st to 10thNight
31%
788
27%
2228
11%
788
43%
788
32%
1331
February11th to 20thNight
28%
704
24%
2098
9%
700
39%
700
31%
1250
February21st to endNight
22%
585
28%
1769
8%
585
38%
585
28%
1045
March1st to 10thNight
32%
540
26%
1980
15%
540
45%
540
26%
1136
March11th to 20thNight
33%
540
25%
1980
15%
540
46%
540
28%
1112
March21st to endNight
34%
594
27%
2178
16%
594
50%
594
30%
1158
April1st to 10thNight
31%
540
26%
1980
14%
540
50%
540
32%
1025
April11th to 20thNight
32%
533
26%
1876
17%
533
46%
533
30%
1029
April21st to endNight
32%
540
30%
1638
15%
540
51%
540
37%
910
May1st to 10thNight
38%
540
27%
1620
18%
540
52%
540
33%
955
May11th to 20thNight
44%
531
21%
1594
16%
531
53%
531
33%
948
May21st to endNight
49%
583
23%
1745
19%
582
61%
582
37%
1007
June1st to 10thNight
69%
540
23%
1620
23%
540
74%
540
45%
857
June11th to 20thNight
67%
540
27%
1620
27%
540
73%
540
53%
791
June21st to endNight
73%
540
26%
1620
28%
540
77%
540
47%
836
July1st to 10thNight
77%
525
23%
1575
25%
525
80%
525
41%
866
July11th to 20thNight
83%
522
33%
1566
36%
522
87%
522
63%
692
July21st to endNight
87%
591
32%
1673
39%
558
89%
558
56%
789
August1st to 10thNight
89%
537
37%
1601
42%
534
91%
534
66%
694
August11th to 20thNight
79%
534
36%
1600
39%
534
81%
534
46%
825
August21st to endNight
85%
594
30%
2042
36%
594
85%
594
46%
971
September1st to 10thNight
76%
540
25%
1980
30%
540
77%
540
38%
981
September11th to 20thNight
70%
540
25%
1980
29%
540
72%
540
31%
1098
September21st to endNight
71%
540
36%
1980
36%
540
77%
540
47%
889
October1st to 10thNight
66%
553
38%
1993
35%
553
73%
553
46%
920
October11th to 20thNight
53%
720
35%
2160
19%
720
63%
720
44%
1127
October21st to endNight
45%
792
33%
2376
19%
792
54%
792
39%
1299
November1st to 10thNight
51%
740
32%
2220
19%
740
61%
740
42%
1198
November11th to 20thNight
48%
904
31%
2424
16%
904
57%
904
46%
1329
November21st to endNight
37%
950
30%
2470
12%
950
48%
950
35%
1516
December1st to 10thNight
38%
950
33%
2470
13%
950
51%
950
38%
1481
December11th to 20thNight
36%
948
31%
2861
14%
948
45%
948
30%
1720
December21st to endNight
34%
1039
18%
4314
11%
1026
46%
1026
25%
2298

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%42443445%7%53%
75087
Night
10%423323447%57%
75070
TransparencyDay
31%6%10%23%22%8%
74812
Night
27%5%9%22%25%11%
74865
SeeingDay
11%7%22%29%23%7%
14065
Night
12%7%28%36%16%1
24109

By Month

Percentage Cloud Cover SE (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
13%6%23313346%57%
1707
11th to 20thDay
14%424323445%55%
1710
21st to endDay
14%6%14323346%54%
1872
February1st to 10thDay
16%6%35%433445%48%
1746
11th to 20thDay
16%7%36%323335%48%
1749
21st to endDay
20%7%2332222453%
1484
March1st to 10thDay
17%5%24433446%47%
1980
11th to 20thDay
15%6%245%23445%49%
1980
21st to endDay
12%5%25%43445%5%50%
2178
April1st to 10thDay
11%6%35%425%45%6%50%
1980
11th to 20thDay
12%5%35%43445%7%49%
2030
21st to endDay
11%5%244245%6%7%49%
2317
May1st to 10thDay
12%4345%2445%8%49%
2340
11th to 20thDay
12%5%36%5%25%5%5%7%44%
2302
21st to endDay
11%6%36%5%36%5%6%8%40%
2531
June1st to 10thDay
5%414435%5%7%9%53%
2340
11th to 20thDay
5%324435%5%6%8%56%
2340
21st to endDay
5%3244345%5%8%57%
2340
July1st to 10thDay
5%425%5%46%5%8%11%45%
2340
11th to 20thDay
311232446%9%64%
2340
21st to endDay
3313437%7%7%11%52%
2546
August1st to 10thDay
221342446%8%65%
2328
11th to 20thDay
7%324436%5%6%9%50%
2301
21st to endDay
42144445%7%10%54%
2310
September1st to 10thDay
7%42442445%7%56%
1980
11th to 20thDay
11%425%6%445%6%7%47%
1980
21st to endDay
9%31332346%7%59%
1980
October1st to 10thDay
6%31343445%7%61%
1949
11th to 20thDay
11%41441234462%
1800
21st to endDay
14%42332323362%
1980
November1st to 10thDay
14%324323345%57%
1858
11th to 20thDay
7%324333347%62%
1753
21st to endDay
15%5%23323336%54%
1710
December1st to 10thDay
14%5%23433445%52%
1710
11th to 20thDay
15%6%35%5%34345%47%
2161
21st to endDay
18%6%24423335%50%
3135
January1st to 10thNight
10%424323435%60%
2458
11th to 20thNight
14%424322335%59%
2470
21st to endNight
14%5%23323345%56%
2711
February1st to 10thNight
15%5%24423245%54%
2228
11th to 20thNight
15%6%24423246%51%
2098
21st to endNight
19%6%23223345%53%
1769
March1st to 10thNight
14%5%35%42445%7%47%
1980
11th to 20thNight
14%6%2433345%6%51%
1980
21st to endNight
10%5%24323447%56%
2178
April1st to 10thNight
9%42332345%10%54%
1980
11th to 20thNight
13%424424348%53%
1876
21st to endNight
10%5%1442435%7%56%
1638
May1st to 10thNight
10%42443445%8%51%
1620
11th to 20thNight
10%4244245%6%9%49%
1593
21st to endNight
9%3344245%7%10%51%
1745
June1st to 10thNight
33134245%6%9%60%
1620
11th to 20thNight
321332346%9%63%
1620
21st to endNight
22234245%7%10%60%
1620
July1st to 10thNight
4323435%5%6%11%54%
1620
11th to 20thNight
221323349%71%
1620
21st to endNight
21133245%6%11%63%
1772
August1st to 10thNight
221111236%8%72%
1611
11th to 20thNight
5%4224235%6%9%58%
1600
21st to endNight
431342447%10%59%
2042
September1st to 10thNight
7%41442445%7%59%
1980
11th to 20thNight
11%5%244345%47%52%
1980
21st to endNight
6%22332335%7%63%
1980
October1st to 10thNight
6%32342345%7%64%
1993
11th to 20thNight
10%323322345%63%
2160
21st to endNight
15%41321223461%
2376
November1st to 10thNight
10%42432333463%
2220
11th to 20thNight
7%31432345%6%62%
2424
21st to endNight
15%5%24423335%55%
2470
December1st to 10thNight
12%6%23323345%57%
2470
11th to 20thNight
13%5%24423346%52%
3036
21st to endNight
16%6%23222235%55%
4532

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
30%47%21%29%9%
1708
11th to 20thDay
32%38%22%27%7%
1710
21st to endDay
33%37%18%29%10%
1872
February1st to 10thDay
39%47%19%21%10%
1746
11th to 20thDay
40%47%20%19%10%
1759
21st to endDay
38%35%15%24%15%
1484
March1st to 10thDay
38%5%7%17%21%12%
1980
11th to 20thDay
39%6%8%18%23%7%
1980
21st to endDay
35%6%10%20%20%8%
2178
April1st to 10thDay
35%5%11%21%18%11%
1980
11th to 20thDay
36%6%10%19%20%10%
2030
21st to endDay
34%6%10%20%24%6%
2317
May1st to 10thDay
34%7%9%23%19%8%
2340
11th to 20thDay
38%7%13%21%19%2
2306
21st to endDay
39%8%12%23%15%2
2531
June1st to 10thDay
25%10%16%27%18%4
2340
11th to 20thDay
25%6%14%30%20%5%
2340
21st to endDay
24%8%11%27%25%5%
2340
July1st to 10thDay
29%10%18%27%14%1
2276
11th to 20thDay
17%7%14%34%22%5%
2271
21st to endDay
21%9%18%33%17%1
2405
August1st to 10thDay
16%6%15%34%26%3
2314
11th to 20thDay
27%10%15%27%20%2
2301
21st to endDay
23%8%15%30%19%5%
2310
September1st to 10thDay
28%6%10%23%25%9%
1980
11th to 20thDay
36%8%11%18%20%7%
1980
21st to endDay
23%5%9%22%28%13%
1980
October1st to 10thDay
22%6%11%22%22%16%
1949
11th to 20thDay
27%47%17%27%18%
1800
21st to endDay
29%36%19%26%16%
1980
November1st to 10thDay
31%47%22%26%10%
1858
11th to 20thDay
24%49%21%30%11%
1753
21st to endDay
34%36%21%25%11%
1710
December1st to 10thDay
34%48%22%24%7%
1710
11th to 20thDay
39%5%6%14%26%10%
2159
21st to endDay
37%35%23%22%9%
3135
January1st to 10thNight
28%37%20%29%13%
2458
11th to 20thNight
30%38%19%29%10%
2470
21st to endNight
32%35%17%27%16%
2711
February1st to 10thNight
34%48%17%23%14%
2228
11th to 20thNight
36%38%17%25%11%
2098
21st to endNight
36%37%15%20%17%
1769
March1st to 10thNight
36%5%7%17%20%14%
1980
11th to 20thNight
34%5%10%16%25%9%
1980
21st to endNight
30%6%11%21%24%8%
2178
April1st to 10thNight
27%6%11%21%20%14%
1980
11th to 20thNight
32%5%9%20%19%15%
1876
21st to endNight
28%6%10%21%28%6%
1638
May1st to 10thNight
31%7%10%23%20%9%
1620
11th to 20thNight
31%8%15%23%20%3
1594
21st to endNight
27%9%17%26%19%3
1746
June1st to 10thNight
21%7%15%31%20%5%
1620
11th to 20thNight
17%6%14%34%21%8%
1620
21st to endNight
19%8%13%25%28%7%
1620
July1st to 10thNight
22%10%15%32%18%3
1575
11th to 20thNight
11%5%12%36%29%7%
1566
21st to endNight
13%7%17%37%23%2
1673
August1st to 10thNight
9%6%12%37%31%6%
1601
11th to 20thNight
21%7%13%31%24%6%
1600
21st to endNight
19%6%13%32%24%5%
2042
September1st to 10thNight
25%5%11%23%26%10%
1980
11th to 20thNight
31%7%11%19%21%11%
1980
21st to endNight
20%39%23%28%17%
1980
October1st to 10thNight
21%39%26%21%19%
1993
11th to 20thNight
25%38%15%27%22%
2160
21st to endNight
29%35%16%27%20%
2376
November1st to 10thNight
27%37%20%27%15%
2220
11th to 20thNight
23%5%8%22%28%15%
2424
21st to endNight
34%47%16%27%12%
2470
December1st to 10thNight
30%47%22%24%12%
2470
11th to 20thNight
34%46%16%27%12%
3037
21st to endNight
33%46%19%26%13%
4532

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
22%13%33%24%7%
270
11th to 20thDay
19%15%36%22%7%1
270
21st to endDay
20%13%38%20%9%
294
February1st to 10thDay
20%14%35%26%5%
240
11th to 20thDay
23%16%39%18%5%
240
21st to endDay
29%16%35%16%4
198
March1st to 10thDay
21%17%34%23%5%
240
11th to 20thDay
21%17%38%18%5%1
240
21st to endDay
14%17%42%20%6%
264
April1st to 10thDay
16%18%33%23%9%1
240
11th to 20thDay
16%14%37%25%9%
308
21st to endDay
14%14%39%22%9%1
577
May1st to 10thDay
13%11%35%32%8%1
603
11th to 20thDay
16%6%30%32%13%3
625
21st to endDay
13%6%27%32%18%4
679
June1st to 10thDay
7%214%40%28%9%
630
11th to 20thDay
5%217%42%29%6%
630
21st to endDay
4114%37%33%11%
630
July1st to 10thDay
7%17%37%33%15%
621
11th to 20thDay
26%33%43%15%
618
21st to endDay
26%28%46%17%
684
August1st to 10thDay
217%31%48%11%
626
11th to 20thDay
9%15%31%43%11%
615
21st to endDay
45%26%39%24%
429
September1st to 10thDay
5%15%20%41%27%
270
11th to 20thDay
6%7%26%39%21%
270
21st to endDay
13%36%24%38%16%
270
October1st to 10thDay
2120%31%35%10%
270
11th to 20thDay
10%7%31%27%21%4
270
21st to endDay
22%12%23%23%16%3
297
November1st to 10thDay
17%7%34%23%14%4
270
11th to 20thDay
11%9%31%31%15%3
270
21st to endDay
18%16%33%22%10%1
270
December1st to 10thDay
17%11%30%28%10%4
270
11th to 20thDay
17%12%37%26%7%
270
21st to endDay
24%11%35%23%7%
297
January1st to 10thNight
13%8%37%32%9%
950
11th to 20thNight
17%12%32%33%6%
950
21st to endNight
15%11%35%32%7%
1043
February1st to 10thNight
19%10%37%29%5%1
788
11th to 20thNight
18%12%39%29%3
704
21st to endNight
22%14%40%21%3
585
March1st to 10thNight
17%11%37%30%6%
540
11th to 20thNight
15%9%39%31%5%
540
21st to endNight
11%12%40%31%5%
594
April1st to 10thNight
10%12%44%29%5%
540
11th to 20thNight
14%10%41%30%5%
533
21st to endNight
11%11%44%26%7%1
540
May1st to 10thNight
11%9%38%35%7%1
540
11th to 20thNight
11%434%36%13%2
531
21st to endNight
9%334%38%16%1
584
June1st to 10thNight
4119%49%24%2
540
11th to 20thNight
3223%55%16%1
540
21st to endNight
3116%46%31%3
540
July1st to 10thNight
411%45%35%5%
525
11th to 20thNight
311%46%37%3
522
21st to endNight
25%48%42%3
591
August1st to 10thNight
117%50%39%2
537
11th to 20thNight
7%7%43%37%5%
534
21st to endNight
41343%42%7%
594
September1st to 10thNight
8%16%42%37%6%
540
11th to 20thNight
14%16%41%35%3
540
21st to endNight
8%16%38%33%5%
540
October1st to 10thNight
7%120%42%27%3
553
11th to 20thNight
12%6%26%37%18%2
720
21st to endNight
17%9%28%31%15%1
792
November1st to 10thNight
11%430%39%15%1
740
11th to 20thNight
9%9%31%38%13%1
904
21st to endNight
17%10%34%29%10%
950
December1st to 10thNight
14%10%35%34%7%
950
11th to 20thNight
18%9%33%35%5%
950
21st to endNight
17%9%36%31%6%
1045
Page generated at 2024-01-28 04:26:32. Version ac07

Copyright 2024 Attilla Danko


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