Bowie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bowie 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
35%
23603
21%
80083
10%
23503
47%
23503
22%
49551

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
17%
752
24%
4310
7%
737
39%
737
12%
2402
January11th to 20thNight
22%
760
27%
3960
9%
740
38%
740
13%
2236
January21st to endNight
20%
829
16%
4447
8%
814
42%
814
12%
2718
February1st to 10thNight
25%
760
19%
2470
9%
760
39%
760
20%
1569
February11th to 20thNight
13%
743
19%
2324
4%
740
32%
740
17%
1479
February21st to endNight
16%
611
24%
1831
6%
611
37%
611
21%
1171
March1st to 10thNight
22%
720
24%
2044
8%
720
40%
720
26%
1262
March11th to 20thNight
22%
720
21%
1980
8%
720
35%
720
23%
1301
March21st to endNight
20%
792
20%
2124
6%
792
32%
792
23%
1446
April1st to 10thNight
20%
720
19%
1800
3%
720
31%
720
22%
1231
April11th to 20thNight
31%
711
21%
1775
6%
711
39%
711
30%
1163
April21st to endNight
32%
720
21%
1800
6%
720
39%
720
27%
1209
May1st to 10thNight
32%
632
16%
1712
7%
632
39%
632
24%
1163
May11th to 20thNight
36%
386
18%
1447
10%
386
45%
386
19%
929
May21st to endNight
51%
388
15%
1551
15%
388
56%
388
23%
914
June1st to 10thNight
53%
360
20%
1440
21%
360
60%
360
25%
833
June11th to 20thNight
50%
360
16%
1440
16%
360
56%
360
21%
866
June21st to endNight
55%
360
17%
1440
16%
360
62%
360
25%
827
July1st to 10thNight
56%
350
16%
1400
18%
350
61%
350
22%
851
July11th to 20thNight
69%
376
16%
1420
18%
376
69%
376
26%
797
July21st to endNight
61%
591
18%
1672
14%
558
67%
558
33%
1021
August1st to 10thNight
62%
537
16%
1600
12%
534
64%
534
28%
1043
August11th to 20thNight
57%
634
16%
1698
10%
634
59%
634
26%
1171
August21st to endNight
59%
792
18%
1980
10%
792
60%
792
32%
1347
September1st to 10thNight
54%
720
22%
1800
11%
720
58%
720
31%
1225
September11th to 20thNight
60%
720
29%
1800
20%
720
64%
720
37%
1146
September21st to endNight
42%
720
20%
2047
14%
720
49%
720
25%
1383
October1st to 10thNight
44%
720
19%
2160
15%
720
50%
720
26%
1392
October11th to 20thNight
40%
720
26%
2160
17%
720
53%
720
29%
1298
October21st to endNight
32%
792
27%
2376
14%
792
49%
792
27%
1445
November1st to 10thNight
34%
740
26%
2348
14%
740
50%
740
30%
1366
November11th to 20thNight
30%
760
25%
2470
13%
760
46%
760
25%
1447
November21st to endNight
32%
760
24%
2644
13%
760
49%
760
24%
1497
December1st to 10thNight
23%
760
20%
2660
5%
760
41%
760
18%
1656
December11th to 20thNight
23%
760
21%
3165
8%
759
39%
759
17%
1867
December21st to endNight
26%
827
14%
4788
10%
817
41%
817
11%
2880

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
14%6%25%5%35%5%6%7%42%
78457
Night
15%6%25%43445%7%44%
80844
TransparencyDay
39%7%12%23%16%3
78167
Night
39%6%11%23%17%3
80653
SeeingDay
18%13%29%24%12%4
14010
Night
17%12%30%28%11%1
23628

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
17%424423346%49%
2526
11th to 20thDay
16%10%45%4345%5%5%41%
2840
21st to endDay
18%8%37%5%34436%38%
3124
February1st to 10thDay
15%6%25%5%46%46%6%40%
1710
11th to 20thDay
19%7%25%43435%7%42%
1743
21st to endDay
19%9%26%434446%39%
1520
March1st to 10thDay
13%6%244245%46%49%
1912
11th to 20thDay
17%5%26%5%3445%6%43%
1980
21st to endDay
18%6%36%5%35%446%40%
2232
April1st to 10thDay
13%6%35%5%25%5%6%6%45%
2160
11th to 20thDay
13%425%4345%46%48%
2134
21st to endDay
18%6%245%3446%6%41%
2160
May1st to 10thDay
16%6%26%4345%7%8%39%
2262
11th to 20thDay
18%5%25%5%35%6%6%8%37%
2446
21st to endDay
14%5%25%5%35%5%7%8%40%
2725
June1st to 10thDay
12%425%435%6%7%9%42%
2520
11th to 20thDay
11%5%25%5%45%6%6%9%42%
2520
21st to endDay
10%4245%36%6%7%11%42%
2520
July1st to 10thDay
10%425%6%46%6%8%9%40%
2520
11th to 20thDay
5%3145%45%7%9%12%44%
2487
21st to endDay
9%5%25%6%47%6%9%10%36%
2547
August1st to 10thDay
9%6%27%6%46%6%8%9%37%
2327
11th to 20thDay
11%5%35%6%35%6%7%9%39%
2183
21st to endDay
10%5%35%6%36%6%7%9%41%
2376
September1st to 10thDay
14%425%5%35%46%6%45%
2160
11th to 20thDay
12%425%5%3446%9%46%
2160
21st to endDay
19%7%25%5%35%5%5%7%39%
1908
October1st to 10thDay
17%5%2443346%6%46%
1800
11th to 20thDay
18%42332345%6%49%
1800
21st to endDay
14%6%25%424446%48%
1980
November1st to 10thDay
12%5%24333447%53%
1728
11th to 20thDay
14%5%243245%5%6%50%
1710
21st to endDay
15%5%34434446%48%
1535
December1st to 10thDay
17%5%25%44447%7%43%
1520
11th to 20thDay
16%7%25%424446%46%
1910
21st to endDay
17%6%36%5%36%5%5%7%38%
2772
January1st to 10thNight
15%7%25%434446%45%
4415
11th to 20thNight
19%7%2432345%6%45%
4120
21st to endNight
19%9%35%423345%42%
4532
February1st to 10thNight
16%7%345%3446%6%42%
2470
11th to 20thNight
19%7%35%5%24345%44%
2322
21st to endNight
17%8%2443335%6%43%
1831
March1st to 10thNight
13%5%25%424446%50%
2044
11th to 20thNight
17%7%25%43345%7%43%
1980
21st to endNight
15%7%36%5%3445%6%41%
2124
April1st to 10thNight
15%7%25%5%35%5%5%7%41%
1800
11th to 20thNight
14%435%4245%47%48%
1775
21st to endNight
19%5%24425%46%8%43%
1800
May1st to 10thNight
17%6%25%5%35%5%5%8%39%
1712
11th to 20thNight
17%6%36%4345%6%9%38%
1447
21st to endNight
14%5%25%4345%7%11%41%
1550
June1st to 10thNight
12%4245%345%7%10%44%
1440
11th to 20thNight
11%436%5%45%5%6%9%41%
1440
21st to endNight
10%425%6%35%6%7%10%42%
1440
July1st to 10thNight
8%6%36%6%45%5%7%10%40%
1440
11th to 20thNight
6%425%445%7%7%10%46%
1468
21st to endNight
8%4245%46%7%8%12%41%
1771
August1st to 10thNight
8%426%6%46%7%8%9%41%
1611
11th to 20thNight
11%5%36%6%45%6%6%9%39%
1698
21st to endNight
11%5%26%5%35%5%5%9%43%
1980
September1st to 10thNight
14%6%245%35%447%45%
1800
11th to 20thNight
11%5%35%425%45%7%50%
1800
21st to endNight
17%6%345%345%5%7%40%
2047
October1st to 10thNight
19%6%35%433346%44%
2160
11th to 20thNight
16%434433347%50%
2160
21st to endNight
16%425%424447%48%
2376
November1st to 10thNight
12%6%25%424445%53%
2348
11th to 20thNight
15%6%24424446%50%
2470
21st to endNight
13%4245%3447%6%49%
2644
December1st to 10thNight
18%6%25%5%3346%7%41%
2660
11th to 20thNight
17%5%2443445%7%44%
3285
21st to endNight
16%6%35%5%36%6%6%7%38%
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
36%48%31%16%4
2527
11th to 20thDay
45%5%10%20%16%4
2840
21st to endDay
46%7%11%23%11%2
3124
February1st to 10thDay
43%6%12%24%13%2
1710
11th to 20thDay
43%49%25%16%3
1752
21st to endDay
47%412%19%14%4
1520
March1st to 10thDay
36%5%12%25%20%3
1912
11th to 20thDay
41%7%10%18%18%6%
1980
21st to endDay
46%5%9%19%17%3
2232
April1st to 10thDay
38%7%12%21%18%5%
2160
11th to 20thDay
36%6%9%22%21%6%
2134
21st to endDay
42%6%11%21%17%4
2160
May1st to 10thDay
40%8%14%21%15%3
2262
11th to 20thDay
43%9%14%19%14%2
2450
21st to endDay
40%9%14%24%12%2
2725
June1st to 10thDay
35%10%15%24%15%1
2520
11th to 20thDay
37%10%13%21%16%2
2520
21st to endDay
33%10%15%23%17%1
2520
July1st to 10thDay
36%11%14%20%16%3
2450
11th to 20thDay
29%10%18%27%14%3
2412
21st to endDay
38%10%15%20%16%1
2405
August1st to 10thDay
38%11%15%24%12%1
2314
11th to 20thDay
38%10%14%22%14%1
2183
21st to endDay
36%10%14%24%13%4
2376
September1st to 10thDay
38%7%13%21%17%4
2160
11th to 20thDay
34%6%11%24%21%4
2160
21st to endDay
44%6%9%20%18%3
1908
October1st to 10thDay
37%6%11%24%19%3
1800
11th to 20thDay
36%5%10%25%21%3
1800
21st to endDay
37%48%26%22%2
1980
November1st to 10thDay
32%5%11%28%19%4
1728
11th to 20thDay
34%5%10%24%22%4
1710
21st to endDay
38%49%28%18%3
1535
December1st to 10thDay
40%6%15%24%12%3
1520
11th to 20thDay
39%5%10%32%12%3
1906
21st to endDay
44%7%13%24%12%1
2772
January1st to 10thNight
39%6%8%26%16%4
4415
11th to 20thNight
40%5%9%25%18%3
4120
21st to endNight
45%47%26%16%1
4532
February1st to 10thNight
41%6%12%25%14%2
2470
11th to 20thNight
44%39%21%18%5%
2324
21st to endNight
42%410%23%17%5%
1831
March1st to 10thNight
36%410%26%20%3
2044
11th to 20thNight
41%5%11%21%18%4
1980
21st to endNight
43%6%10%19%16%6%
2124
April1st to 10thNight
42%6%10%19%20%5%
1800
11th to 20thNight
36%6%12%21%20%6%
1775
21st to endNight
40%6%10%23%16%5%
1800
May1st to 10thNight
42%7%13%21%13%4
1712
11th to 20thNight
43%9%11%18%17%3
1448
21st to endNight
36%9%19%20%13%2
1551
June1st to 10thNight
35%8%12%25%18%2
1440
11th to 20thNight
38%9%14%23%13%3
1440
21st to endNight
35%8%16%21%18%3
1440
July1st to 10thNight
38%9%18%19%12%3
1400
11th to 20thNight
31%10%16%25%15%2
1420
21st to endNight
31%10%16%27%15%1
1672
August1st to 10thNight
36%11%17%21%15%1
1600
11th to 20thNight
40%10%14%21%12%2
1698
21st to endNight
38%8%14%23%14%4
1980
September1st to 10thNight
39%7%10%22%16%5%
1800
11th to 20thNight
33%6%10%25%22%4
1800
21st to endNight
41%8%11%18%18%3
2047
October1st to 10thNight
41%6%10%22%18%3
2160
11th to 20thNight
36%49%27%20%3
2160
21st to endNight
36%6%8%25%21%4
2376
November1st to 10thNight
34%5%10%25%21%6%
2348
11th to 20thNight
36%410%22%22%6%
2470
21st to endNight
34%5%12%25%21%3
2644
December1st to 10thNight
43%5%12%24%15%3
2660
11th to 20thNight
40%411%23%19%3
3288
21st to endNight
43%7%14%23%11%1
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
26%24%31%14%41
184
11th to 20thDay
24%28%33%13%2
270
21st to endDay
20%25%36%16%11
297
February1st to 10thDay
23%24%36%13%3
270
11th to 20thDay
32%23%36%7%2
350
21st to endDay
29%21%34%13%2
362
March1st to 10thDay
21%26%32%19%2
420
11th to 20thDay
27%20%33%14%41
420
21st to endDay
23%21%34%16%5%1
462
April1st to 10thDay
19%24%36%16%41
420
11th to 20thDay
16%19%34%20%8%2
412
21st to endDay
25%14%36%18%5%1
420
May1st to 10thDay
23%17%31%19%8%2
423
11th to 20thDay
20%11%34%24%9%2
447
21st to endDay
20%6%22%30%17%4
485
June1st to 10thDay
13%7%30%27%19%4
450
11th to 20thDay
14%8%28%31%14%5%
450
21st to endDay
11%6%27%34%17%5%
450
July1st to 10thDay
10%220%36%24%8%
445
11th to 20thDay
3118%42%28%7%
444
21st to endDay
11%223%36%24%5%
488
August1st to 10thDay
10%5%20%34%24%7%
446
11th to 20thDay
13%317%35%24%9%
439
21st to endDay
9%322%32%23%11%
495
September1st to 10thDay
18%5%18%28%20%12%
450
11th to 20thDay
13%325%31%20%8%
450
21st to endDay
22%11%27%27%10%4
450
October1st to 10thDay
23%7%22%25%18%5%
450
11th to 20thDay
18%12%29%25%14%2
450
21st to endDay
18%13%36%23%8%2
495
November1st to 10thDay
16%13%35%22%10%4
393
11th to 20thDay
17%19%33%21%8%2
370
21st to endDay
22%19%29%20%11%
195
December1st to 10thDay
19%26%36%14%5%1
180
11th to 20thDay
22%23%31%19%5%
180
21st to endDay
23%17%33%21%6%
198
January1st to 10thNight
19%20%39%19%3
760
11th to 20thNight
23%17%34%22%5%
760
21st to endNight
19%20%38%22%2
836
February1st to 10thNight
19%18%35%25%3
760
11th to 20thNight
24%24%35%16%1
743
21st to endNight
23%19%38%17%2
611
March1st to 10thNight
18%18%38%23%3
720
11th to 20thNight
22%18%36%19%5%1
720
21st to endNight
19%15%41%20%41
792
April1st to 10thNight
20%22%36%18%5%
720
11th to 20thNight
14%16%35%28%7%
711
21st to endNight
22%11%32%27%8%
720
May1st to 10thNight
20%10%33%26%10%1
632
11th to 20thNight
17%10%32%30%11%
386
21st to endNight
16%423%37%19%2
389
June1st to 10thNight
13%227%38%19%1
360
11th to 20thNight
9%6%28%39%16%1
360
21st to endNight
10%326%46%14%1
360
July1st to 10thNight
8%223%38%27%2
350
11th to 20thNight
6%115%45%30%3
376
21st to endNight
7%221%41%25%4
591
August1st to 10thNight
9%315%46%26%2
537
11th to 20thNight
11%318%39%26%2
634
21st to endNight
13%316%37%26%5%
792
September1st to 10thNight
17%319%33%24%4
720
11th to 20thNight
13%416%38%25%4
720
21st to endNight
21%5%25%32%17%1
720
October1st to 10thNight
19%8%23%28%18%5%
720
11th to 20thNight
17%11%27%31%13%1
720
21st to endNight
19%13%33%24%11%1
792
November1st to 10thNight
15%10%35%27%11%2
740
11th to 20thNight
18%18%30%25%9%
760
21st to endNight
16%17%33%26%8%1
760
December1st to 10thNight
21%18%33%19%8%1
760
11th to 20thNight
18%15%39%22%6%
760
21st to endNight
19%17%33%29%3
836
Page generated at 2024-02-22 06:05:48. Version ac07

Copyright 2024 Attilla Danko


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