Barred Owl Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barred Owl 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
29%
22575
14%
74765
8%
22534
36%
22534
16%
53214

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
15%
760
8%
2649
2%
757
21%
757
7%
2134
January11th to 20thNight
17%
736
9%
2574
4%
736
22%
736
8%
2045
January21st to endNight
22%
792
14%
2691
8%
792
30%
792
13%
1932
February1st to 10thNight
15%
720
10%
2340
3%
720
24%
720
9%
1816
February11th to 20thNight
16%
701
13%
2275
4%
700
28%
700
13%
1665
February21st to endNight
23%
592
15%
1779
7%
592
33%
592
14%
1318
March1st to 10thNight
20%
720
15%
2150
8%
720
28%
720
15%
1599
March11th to 20thNight
22%
720
17%
1979
7%
720
31%
720
17%
1431
March21st to endNight
28%
792
21%
2069
9%
792
36%
792
20%
1448
April1st to 10thNight
22%
720
15%
1800
5%
720
27%
720
19%
1326
April11th to 20thNight
26%
711
17%
1775
6%
711
32%
711
20%
1282
April21st to endNight
28%
608
16%
1688
7%
608
34%
608
18%
1233
May1st to 10thNight
34%
360
17%
1440
14%
360
43%
360
17%
930
May11th to 20thNight
32%
354
21%
1416
16%
354
49%
354
19%
873
May21st to endNight
37%
389
14%
1551
11%
388
50%
388
24%
908
June1st to 10thNight
39%
360
10%
1440
10%
360
48%
360
17%
945
June11th to 20thNight
41%
360
13%
1440
16%
360
49%
360
21%
855
June21st to endNight
38%
360
11%
1440
14%
360
45%
360
18%
929
July1st to 10thNight
49%
350
15%
1400
19%
350
57%
350
25%
795
July11th to 20thNight
52%
348
16%
1392
23%
348
58%
348
24%
813
July21st to endNight
54%
394
15%
1486
17%
372
58%
372
23%
851
August1st to 10thNight
52%
402
16%
1466
14%
400
58%
400
23%
899
August11th to 20thNight
58%
534
18%
1598
13%
534
61%
534
32%
1001
August21st to endNight
46%
792
18%
1980
8%
792
50%
792
31%
1317
September1st to 10thNight
46%
720
17%
1800
9%
720
49%
720
32%
1205
September11th to 20thNight
51%
720
22%
1800
13%
720
55%
720
35%
1171
September21st to endNight
42%
720
21%
2037
14%
720
48%
720
26%
1342
October1st to 10thNight
36%
720
17%
2160
11%
720
44%
720
20%
1489
October11th to 20thNight
26%
720
14%
2160
7%
720
35%
720
16%
1580
October21st to endNight
25%
792
13%
2510
7%
792
33%
792
13%
1878
November1st to 10thNight
28%
740
16%
2407
10%
740
36%
740
17%
1667
November11th to 20thNight
22%
760
16%
2660
10%
760
33%
760
13%
1918
November21st to endNight
20%
760
10%
2660
5%
760
27%
760
10%
2032
December1st to 10thNight
17%
760
7%
2660
3%
760
22%
760
7%
2172
December11th to 20thNight
18%
759
11%
3245
6%
759
26%
759
8%
2458
December21st to endNight
13%
829
6%
4848
2%
817
19%
817
4%
3957

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
17%9%47%6%35%5%5%7%33%
74738
Night
17%10%47%6%35%45%6%32%
75016
TransparencyDay
50%6%11%20%11%1
74443
Night
52%6%11%20%10%1
74845
SeeingDay
22%15%30%20%10%3
13352
Night
22%12%29%26%10%1
22585

By Month

Percentage Cloud Cover NE (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
16%16%5%11%9%35%45%5%22%
1517
11th to 20thDay
18%15%5%11%7%46%345%23%
1464
21st to endDay
12%15%5%9%8%5%5%5%5%6%25%
1662
February1st to 10thDay
14%15%5%10%8%45%5%6%5%23%
1620
11th to 20thDay
13%14%5%9%6%35%446%29%
1573
21st to endDay
19%13%48%7%26%5%5%5%25%
1476
March1st to 10thDay
16%11%5%8%8%45%5%45%30%
1805
11th to 20thDay
16%11%5%7%7%46%446%31%
1980
21st to endDay
19%10%35%5%3445%5%37%
2286
April1st to 10thDay
23%9%36%5%34446%33%
2160
11th to 20thDay
22%7%36%5%33445%37%
2134
21st to endDay
22%10%36%6%345%45%32%
2287
May1st to 10thDay
19%7%37%6%35%45%5%35%
2520
11th to 20thDay
15%7%46%6%35%45%6%39%
2478
21st to endDay
16%5%35%6%45%5%6%6%39%
2725
June1st to 10thDay
20%7%46%5%46%5%5%7%30%
2520
11th to 20thDay
14%6%25%5%36%6%6%8%40%
2520
21st to endDay
17%7%35%6%45%6%7%7%32%
2520
July1st to 10thDay
11%5%25%5%36%6%7%9%40%
2520
11th to 20thDay
11%6%35%5%45%5%7%9%40%
2520
21st to endDay
11%5%25%5%36%5%7%10%40%
2744
August1st to 10thDay
10%5%26%5%46%6%6%8%40%
2458
11th to 20thDay
11%5%27%6%46%6%6%8%40%
2285
21st to endDay
13%6%36%5%35%5%6%9%40%
2376
September1st to 10thDay
13%5%35%6%35%5%5%8%42%
2160
11th to 20thDay
12%5%25%5%345%6%9%45%
2160
21st to endDay
15%6%25%5%35%6%6%7%39%
1918
October1st to 10thDay
19%7%46%5%4446%7%35%
1800
11th to 20thDay
22%8%36%6%36%5%5%7%29%
1800
21st to endDay
26%8%47%6%35%446%27%
1845
November1st to 10thDay
15%8%46%6%45%5%6%7%34%
1667
11th to 20thDay
19%11%47%6%46%5%5%6%28%
1520
21st to endDay
20%12%48%8%47%6%5%5%21%
1520
December1st to 10thDay
20%18%5%9%8%45%5%5%6%16%
1520
11th to 20thDay
21%13%5%8%7%35%5%46%24%
1906
21st to endDay
28%15%7%11%6%2422319%
2772
January1st to 10thNight
17%16%6%11%8%45%5%46%18%
2649
11th to 20thNight
17%16%6%10%7%35%44423%
2574
21st to endNight
12%14%6%9%6%35%45%6%30%
2691
February1st to 10thNight
14%14%5%11%9%46%5%5%6%22%
2340
11th to 20thNight
14%12%5%11%8%3445%5%30%
2273
21st to endNight
16%12%48%7%45%46%6%29%
1779
March1st to 10thNight
16%13%5%9%7%45%445%29%
2140
11th to 20thNight
16%11%5%7%7%24345%35%
1979
21st to endNight
17%7%46%6%35%45%5%39%
2069
April1st to 10thNight
20%9%37%6%35%346%34%
1800
11th to 20thNight
19%9%36%6%34446%36%
1775
21st to endNight
20%9%37%6%44447%32%
1688
May1st to 10thNight
21%7%35%5%345%6%7%36%
1440
11th to 20thNight
17%8%35%4345%5%7%40%
1415
21st to endNight
13%6%26%5%335%5%8%45%
1550
June1st to 10thNight
15%6%37%6%35%6%7%8%34%
1440
11th to 20thNight
14%5%26%5%3446%8%43%
1440
21st to endNight
17%8%35%5%35%5%6%8%38%
1440
July1st to 10thNight
10%5%26%5%35%5%5%8%46%
1440
11th to 20thNight
12%5%35%5%35%5%6%9%43%
1440
21st to endNight
9%6%246%46%5%6%9%44%
1574
August1st to 10thNight
8%6%47%6%445%6%9%43%
1476
11th to 20thNight
9%5%35%6%35%5%6%9%46%
1598
21st to endNight
11%5%36%5%35%46%8%45%
1980
September1st to 10thNight
11%5%35%6%35%5%5%6%46%
1800
11th to 20thNight
15%42443435%7%48%
1800
21st to endNight
17%5%26%5%2445%6%43%
2037
October1st to 10thNight
17%7%35%6%35%45%6%37%
2160
11th to 20thNight
22%8%45%6%45%45%7%30%
2160
21st to endNight
23%10%46%5%45%5%46%28%
2510
November1st to 10thNight
19%10%36%5%33446%35%
2407
11th to 20thNight
19%10%47%6%36%5%5%6%29%
2660
21st to endNight
22%12%49%6%45%45%7%23%
2660
December1st to 10thNight
21%16%5%9%7%46%5%5%6%17%
2660
11th to 20thNight
21%14%5%9%6%3443426%
3288
21st to endNight
31%17%410%5%3433418%
4884

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
64%6%10%14%6%
1518
11th to 20thDay
64%5%8%12%10%1
1464
21st to endDay
60%5%13%13%8%1
1662
February1st to 10thDay
61%6%9%17%42
1620
11th to 20thDay
56%5%11%17%9%1
1582
21st to endDay
59%6%9%14%10%1
1476
March1st to 10thDay
56%6%10%17%10%1
1808
11th to 20thDay
54%412%15%12%3
1980
21st to endDay
49%5%9%18%14%5%
2286
April1st to 10thDay
53%47%19%13%3
2160
11th to 20thDay
50%47%21%16%2
2134
21st to endDay
54%5%8%14%14%4
2287
May1st to 10thDay
50%5%7%19%15%4
2520
11th to 20thDay
45%6%8%22%17%3
2482
21st to endDay
45%7%12%21%13%3
2725
June1st to 10thDay
52%7%9%18%12%1
2520
11th to 20thDay
41%8%11%24%13%3
2520
21st to endDay
49%8%13%20%11%1
2520
July1st to 10thDay
37%8%13%28%14%1
2450
11th to 20thDay
37%8%15%27%11%
2445
21st to endDay
39%8%15%27%11%
2591
August1st to 10thDay
39%9%16%25%10%
2444
11th to 20thDay
40%9%15%26%9%1
2285
21st to endDay
39%8%14%27%12%1
2376
September1st to 10thDay
40%6%14%28%12%
2160
11th to 20thDay
36%6%13%32%12%1
2160
21st to endDay
44%7%14%27%9%
1918
October1st to 10thDay
48%7%12%22%10%1
1800
11th to 20thDay
55%7%15%16%7%1
1800
21st to endDay
59%5%12%15%8%1
1845
November1st to 10thDay
48%6%16%22%7%1
1667
11th to 20thDay
57%6%13%14%9%1
1520
21st to endDay
64%7%12%10%7%1
1520
December1st to 10thDay
68%6%11%10%31
1520
11th to 20thDay
62%6%13%14%5%
1906
21st to endDay
72%37%15%3
2772
January1st to 10thNight
67%6%9%12%5%
2649
11th to 20thNight
66%5%9%11%8%1
2574
21st to endNight
55%5%10%18%11%1
2691
February1st to 10thNight
62%6%10%15%7%1
2340
11th to 20thNight
57%5%10%19%8%1
2275
21st to endNight
56%5%9%19%10%1
1779
March1st to 10thNight
57%410%16%11%2
2150
11th to 20thNight
53%410%19%12%3
1980
21st to endNight
48%49%19%16%5%
2069
April1st to 10thNight
52%48%19%15%2
1800
11th to 20thNight
49%5%7%21%16%1
1775
21st to endNight
52%6%7%16%16%3
1688
May1st to 10thNight
47%5%7%20%15%5%
1440
11th to 20thNight
43%5%8%23%18%3
1416
21st to endNight
38%6%15%20%18%3
1551
June1st to 10thNight
46%8%13%22%10%1
1440
11th to 20thNight
40%6%10%25%17%2
1440
21st to endNight
44%8%13%20%14%1
1440
July1st to 10thNight
36%6%12%27%18%2
1400
11th to 20thNight
37%7%12%30%13%
1392
21st to endNight
36%8%15%26%14%
1486
August1st to 10thNight
38%9%16%24%13%1
1466
11th to 20thNight
35%7%17%29%12%
1598
21st to endNight
36%8%14%29%12%
1980
September1st to 10thNight
37%7%11%29%14%1
1800
11th to 20thNight
35%7%13%35%9%2
1800
21st to endNight
41%6%11%31%10%
2037
October1st to 10thNight
47%7%10%22%13%1
2160
11th to 20thNight
53%6%11%21%8%
2160
21st to endNight
57%6%12%16%8%
2510
November1st to 10thNight
50%5%14%21%9%1
2407
11th to 20thNight
54%7%11%18%9%1
2660
21st to endNight
60%7%13%15%5%
2660
December1st to 10thNight
67%7%10%12%4
2660
11th to 20thNight
61%6%9%16%7%1
3288
21st to endNight
72%47%12%4
4884

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%21%34%18%41
180
11th to 20thDay
28%20%30%18%4
166
21st to endDay
21%18%37%20%4
212
February1st to 10thDay
31%26%33%11%
240
11th to 20thDay
26%29%36%8%1
240
21st to endDay
31%23%29%15%3
342
March1st to 10thDay
26%18%33%19%4
420
11th to 20thDay
26%20%33%17%31
420
21st to endDay
32%18%26%15%7%1
462
April1st to 10thDay
30%19%30%14%6%1
420
11th to 20thDay
33%16%23%16%10%2
412
21st to endDay
30%19%28%15%7%2
420
May1st to 10thDay
25%14%32%20%7%3
423
11th to 20thDay
19%18%32%20%8%3
447
21st to endDay
19%14%32%22%12%1
485
June1st to 10thDay
24%12%31%21%9%2
450
11th to 20thDay
16%14%30%25%12%3
450
21st to endDay
18%14%30%24%11%4
450
July1st to 10thDay
11%7%27%35%16%3
445
11th to 20thDay
13%8%30%30%15%5%
444
21st to endDay
14%8%30%28%15%4
488
August1st to 10thDay
13%8%28%28%19%4
446
11th to 20thDay
12%5%26%29%19%9%
439
21st to endDay
15%11%27%23%14%9%
495
September1st to 10thDay
15%12%29%19%17%9%
450
11th to 20thDay
12%9%28%24%19%9%
450
21st to endDay
17%12%29%21%16%5%
450
October1st to 10thDay
24%13%26%19%13%5%
450
11th to 20thDay
26%20%27%19%6%1
450
21st to endDay
29%19%26%20%6%
427
November1st to 10thDay
24%19%30%18%8%1
361
11th to 20thDay
28%19%33%12%6%1
180
21st to endDay
28%19%35%12%41
180
December1st to 10thDay
32%13%38%15%21
180
11th to 20thDay
27%27%32%10%3
180
21st to endDay
32%20%32%12%31
198
January1st to 10thNight
27%15%34%20%4
760
11th to 20thNight
28%17%27%21%6%1
736
21st to endNight
18%12%37%27%6%
792
February1st to 10thNight
23%16%36%21%4
720
11th to 20thNight
23%16%39%18%4
703
21st to endNight
25%18%29%24%4
592
March1st to 10thNight
24%14%34%25%3
720
11th to 20thNight
23%18%32%21%6%
720
21st to endNight
24%15%27%26%8%
792
April1st to 10thNight
27%13%31%24%5%
720
11th to 20thNight
23%19%27%23%8%
711
21st to endNight
25%12%28%26%7%1
608
May1st to 10thNight
24%8%28%30%10%1
360
11th to 20thNight
21%12%28%30%9%
354
21st to endNight
14%6%38%28%13%
389
June1st to 10thNight
18%6%32%35%10%
360
11th to 20thNight
17%8%27%33%14%1
360
21st to endNight
19%6%29%31%14%1
360
July1st to 10thNight
9%5%28%43%15%1
350
11th to 20thNight
13%5%24%43%15%1
348
21st to endNight
10%5%24%45%15%2
394
August1st to 10thNight
10%422%42%22%
402
11th to 20thNight
11%219%39%26%2
534
21st to endNight
12%7%25%35%19%2
792
September1st to 10thNight
13%5%30%31%18%2
720
11th to 20thNight
16%7%21%32%20%4
720
21st to endNight
18%9%25%26%20%3
720
October1st to 10thNight
20%13%25%26%15%2
720
11th to 20thNight
25%12%30%24%8%1
720
21st to endNight
27%15%26%26%6%
792
November1st to 10thNight
27%12%27%24%9%
740
11th to 20thNight
23%17%32%18%9%1
760
21st to endNight
30%15%26%23%6%
760
December1st to 10thNight
30%15%29%21%4
760
11th to 20thNight
28%16%29%21%5%1
760
21st to endNight
33%15%29%19%4
836
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Copyright 2024 Attilla Danko


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