Trapshoot
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Trapshoot 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
62%
23278
28%
74674
24%
23242
68%
23242
39%
39415

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
49%
757
18%
2646
15%
756
55%
756
25%
1570
January11th to 20thNight
54%
736
21%
2540
18%
736
62%
736
26%
1464
January21st to endNight
56%
792
26%
2574
24%
792
61%
792
30%
1527
February1st to 10thNight
55%
720
25%
2340
23%
720
62%
720
33%
1288
February11th to 20thNight
54%
700
27%
2127
22%
700
63%
700
35%
1174
February21st to endNight
50%
592
25%
1776
21%
592
59%
592
31%
1031
March1st to 10thNight
47%
720
18%
2160
15%
720
54%
720
27%
1346
March11th to 20thNight
52%
720
22%
1995
19%
720
57%
720
32%
1216
March21st to endNight
45%
792
17%
2048
9%
792
51%
792
31%
1278
April1st to 10thNight
51%
720
23%
1800
12%
720
55%
720
35%
1114
April11th to 20thNight
54%
711
26%
1779
13%
711
58%
711
40%
1048
April21st to endNight
57%
720
23%
1800
11%
720
61%
720
45%
1024
May1st to 10thNight
53%
606
27%
1686
17%
606
58%
606
40%
939
May11th to 20thNight
65%
354
27%
1416
29%
354
70%
354
36%
660
May21st to endNight
66%
388
21%
1552
24%
388
71%
388
33%
777
June1st to 10thNight
70%
360
25%
1440
30%
360
76%
360
39%
656
June11th to 20thNight
71%
360
32%
1440
39%
360
80%
360
54%
536
June21st to endNight
79%
360
32%
1440
43%
360
85%
360
54%
541
July1st to 10thNight
84%
350
35%
1400
44%
350
90%
350
68%
457
July11th to 20thNight
85%
348
39%
1392
48%
348
90%
348
70%
445
July21st to endNight
84%
444
40%
1536
45%
420
86%
420
60%
582
August1st to 10thNight
83%
537
35%
1602
29%
534
85%
534
57%
745
August11th to 20thNight
78%
703
37%
1771
23%
703
80%
703
70%
855
August21st to endNight
80%
792
44%
1980
27%
792
81%
792
79%
896
September1st to 10thNight
79%
720
44%
1800
28%
720
82%
720
76%
831
September11th to 20thNight
77%
720
44%
1815
32%
720
81%
720
67%
883
September21st to endNight
76%
720
41%
1980
34%
720
82%
720
63%
922
October1st to 10thNight
68%
720
32%
2150
28%
720
77%
720
52%
1037
October11th to 20thNight
74%
720
38%
2160
38%
720
80%
720
56%
981
October21st to endNight
69%
792
37%
2419
36%
792
75%
792
53%
1120
November1st to 10thNight
60%
740
28%
2405
28%
740
66%
740
36%
1277
November11th to 20thNight
61%
760
27%
2470
25%
760
68%
760
39%
1280
November21st to endNight
58%
760
28%
2574
25%
760
66%
760
36%
1349
December1st to 10thNight
55%
760
23%
2660
22%
760
62%
760
28%
1499
December11th to 20thNight
53%
760
19%
3207
20%
759
58%
759
19%
2096
December21st to endNight
44%
824
13%
4794
18%
817
51%
817
12%
2971

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
342442445%7%60%
74789
Night
45%2443445%8%57%
74997
TransparencyDay
23%6%9%21%24%18%
74497
Night
24%6%11%23%22%13%
74811
SeeingDay
10%15%26%26%17%5%
13877
Night
7%8%17%39%25%4
23298

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
47%37%6%36%7%8%9%40%
1519
11th to 20thDay
46%25%5%45%6%7%9%48%
1504
21st to endDay
49%26%5%46%7%8%9%41%
1782
February1st to 10thDay
46%35%5%36%47%7%51%
1620
11th to 20thDay
36%46%5%36%46%8%50%
1720
21st to endDay
17%25%6%35%6%6%9%49%
1480
March1st to 10thDay
47%37%7%46%5%7%10%38%
1800
11th to 20thDay
5%8%36%425%5%7%9%44%
1962
21st to endDay
28%36%5%35%5%6%9%46%
2308
April1st to 10thDay
46%46%7%346%7%9%44%
2160
11th to 20thDay
45%26%435%5%5%8%54%
2129
21st to endDay
5%6%24435%447%56%
2160
May1st to 10thDay
3425%42345%7%60%
2271
11th to 20thDay
5%42443345%7%59%
2477
21st to endDay
6%6%26%5%345%6%6%50%
2723
June1st to 10thDay
43245%3345%8%59%
2520
11th to 20thDay
2212222335%75%
2520
21st to endDay
221222224476%
2520
July1st to 10thDay
11221333480%
2520
11th to 20thDay
111111233483%
2520
21st to endDay
2212223345%74%
2687
August1st to 10thDay
2212323345%74%
2328
11th to 20thDay
21121223482%
2131
21st to endDay
11111222386%
2376
September1st to 10thDay
21111223483%
2160
11th to 20thDay
3212213335%74%
2144
21st to endDay
4213312337%73%
1980
October1st to 10thDay
3423323346%67%
1805
11th to 20thDay
2313323347%68%
1800
21st to endDay
33233235%5%6%65%
1936
November1st to 10thDay
5%5%245%25%447%57%
1674
11th to 20thDay
35%24436%6%6%10%52%
1710
21st to endDay
26%34335%5%7%8%53%
1601
December1st to 10thDay
6%6%26%5%35%5%8%9%45%
1520
11th to 20thDay
10%8%37%6%6%7%7%7%10%30%
1928
21st to endDay
37%38%7%47%6%7%12%36%
2794
January1st to 10thNight
5%8%36%6%46%6%8%11%39%
2646
11th to 20thNight
37%36%5%36%6%7%10%45%
2540
21st to endNight
5%8%36%5%36%5%7%8%44%
2574
February1st to 10thNight
35%35%5%346%6%9%52%
2340
11th to 20thNight
26%35%5%346%7%10%49%
2126
21st to endNight
26%35%5%5%5%5%6%9%50%
1776
March1st to 10thNight
38%36%5%36%6%6%9%44%
2160
11th to 20thNight
38%26%435%6%7%9%46%
1995
21st to endNight
35%36%6%45%6%6%8%49%
2048
April1st to 10thNight
36%35%5%36%5%6%10%48%
1800
11th to 20thNight
342443446%8%56%
1779
21st to endNight
442442346%8%60%
1800
May1st to 10thNight
6%5%25%423436%61%
1686
11th to 20thNight
5%423425%45%7%58%
1416
21st to endNight
45%244345%6%8%54%
1552
June1st to 10thNight
5%32442345%8%60%
1440
11th to 20thNight
2212223245%75%
1440
21st to endNight
221232323376%
1440
July1st to 10thNight
11121234481%
1440
11th to 20thNight
111111133482%
1440
21st to endNight
321231222477%
1626
August1st to 10thNight
321332335%472%
1611
11th to 20thNight
2212211345%78%
1771
21st to endNight
21111123484%
1980
September1st to 10thNight
211221222483%
1800
11th to 20thNight
3212212235%77%
1815
21st to endNight
2312323235%75%
1980
October1st to 10thNight
4322323335%70%
2150
11th to 20thNight
3312223347%71%
2160
21st to endNight
4412223337%69%
2419
November1st to 10thNight
46%25%4245%6%8%55%
2405
11th to 20thNight
24245%345%6%9%55%
2470
21st to endNight
2425%5%3446%9%55%
2574
December1st to 10thNight
5%7%245%35%5%7%9%48%
2660
11th to 20thNight
11%8%37%7%45%6%8%11%31%
3276
21st to endNight
5%8%48%7%5%7%7%7%9%32%
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
34%11%15%26%12%1
1519
11th to 20thDay
30%8%17%23%16%6%
1504
21st to endDay
36%8%12%25%18%2
1782
February1st to 10thDay
32%5%14%25%19%5%
1620
11th to 20thDay
31%5%14%28%19%4
1730
21st to endDay
29%8%16%26%17%4
1480
March1st to 10thDay
40%6%14%23%15%2
1800
11th to 20thDay
34%7%15%21%19%4
1962
21st to endDay
32%9%21%23%12%3
2308
April1st to 10thDay
33%8%15%24%16%4
2160
11th to 20thDay
27%6%12%29%21%5%
2132
21st to endDay
28%5%12%28%23%4
2160
May1st to 10thDay
23%5%9%29%29%5%
2271
11th to 20thDay
25%5%9%27%28%7%
2480
21st to endDay
32%7%11%25%22%3
2724
June1st to 10thDay
23%5%8%24%30%10%
2520
11th to 20thDay
13%35%22%36%21%
2520
21st to endDay
12%3314%35%33%
2520
July1st to 10thDay
8%438%25%51%
2451
11th to 20thDay
7%3210%28%50%
2445
21st to endDay
13%437%23%49%
2538
August1st to 10thDay
13%3411%25%43%
2312
11th to 20thDay
9%2210%30%47%
2131
21st to endDay
7%219%34%46%
2376
September1st to 10thDay
8%2211%29%50%
2160
11th to 20thDay
13%45%17%35%26%
2144
21st to endDay
14%35%20%36%23%
1980
October1st to 10thDay
20%47%20%31%19%
1805
11th to 20thDay
15%49%24%31%17%
1800
21st to endDay
18%5%9%27%26%15%
1936
November1st to 10thDay
27%5%11%22%25%9%
1674
11th to 20thDay
24%8%15%27%22%4
1710
21st to endDay
26%6%11%27%24%5%
1601
December1st to 10thDay
32%8%11%26%18%4
1520
11th to 20thDay
46%10%9%22%12%2
1928
21st to endDay
36%11%16%24%12%1
2794
January1st to 10thNight
35%8%16%28%12%1
2646
11th to 20thNight
31%9%15%24%14%6%
2540
21st to endNight
35%6%13%24%20%3
2574
February1st to 10thNight
29%7%12%28%20%5%
2340
11th to 20thNight
28%6%13%32%19%2
2127
21st to endNight
28%9%15%28%15%5%
1776
March1st to 10thNight
34%9%15%25%14%3
2160
11th to 20thNight
30%8%14%23%20%4
1995
21st to endNight
29%10%21%24%14%2
2048
April1st to 10thNight
29%9%17%27%15%4
1800
11th to 20thNight
25%7%17%29%18%5%
1779
21st to endNight
22%7%17%33%18%4
1800
May1st to 10thNight
25%5%10%27%29%4
1686
11th to 20thNight
24%5%15%29%20%7%
1416
21st to endNight
25%8%15%30%19%3
1552
June1st to 10thNight
22%5%12%24%28%8%
1440
11th to 20thNight
13%39%22%34%18%
1440
21st to endNight
15%2417%32%30%
1440
July1st to 10thNight
8%249%29%48%
1400
11th to 20thNight
7%2211%28%50%
1392
21st to endNight
12%3410%23%49%
1536
August1st to 10thNight
15%4312%27%37%
1602
11th to 20thNight
10%4211%29%44%
1771
21st to endNight
7%2210%34%45%
1980
September1st to 10thNight
9%236%33%48%
1800
11th to 20thNight
13%3420%36%25%
1815
21st to endNight
13%35%21%34%24%
1980
October1st to 10thNight
19%37%21%30%19%
2150
11th to 20thNight
14%47%25%32%18%
2160
21st to endNight
17%49%28%29%13%
2419
November1st to 10thNight
25%7%11%25%21%10%
2405
11th to 20thNight
24%7%13%28%24%4
2470
21st to endNight
26%6%11%26%23%7%
2574
December1st to 10thNight
30%9%12%24%20%4
2660
11th to 20thNight
40%11%12%20%16%2
3276
21st to endNight
40%12%15%19%12%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
24%13%26%21%13%3
180
11th to 20thDay
16%18%24%24%15%5%
200
21st to endDay
11%14%29%23%19%4
374
February1st to 10thDay
16%16%25%26%14%3
340
11th to 20thDay
15%16%26%30%12%1
403
21st to endDay
14%18%25%32%10%1
346
March1st to 10thDay
19%22%27%22%9%2
420
11th to 20thDay
20%17%26%19%15%2
420
21st to endDay
17%24%28%20%10%
462
April1st to 10thDay
15%24%28%23%9%2
420
11th to 20thDay
18%25%24%21%11%2
412
21st to endDay
16%20%22%24%15%3
420
May1st to 10thDay
14%22%26%23%12%3
423
11th to 20thDay
14%19%32%17%11%7%
448
21st to endDay
14%16%23%24%16%8%
485
June1st to 10thDay
9%18%25%24%16%9%
450
11th to 20thDay
10%17%33%24%13%4
450
21st to endDay
213%30%28%18%8%
450
July1st to 10thDay
39%35%24%22%8%
446
11th to 20thDay
110%30%29%20%10%
444
21st to endDay
37%26%32%23%9%
487
August1st to 10thDay
48%30%24%24%11%
447
11th to 20thDay
211%25%28%21%12%
437
21st to endDay
210%28%31%23%6%
495
September1st to 10thDay
46%28%31%24%7%
450
11th to 20thDay
6%14%24%30%22%4
450
21st to endDay
6%13%28%29%20%3
450
October1st to 10thDay
7%14%27%26%20%6%
450
11th to 20thDay
9%16%18%29%23%5%
450
21st to endDay
9%17%20%29%21%5%
451
November1st to 10thDay
14%13%16%28%23%7%
270
11th to 20thDay
8%10%24%26%22%10%
270
21st to endDay
10%15%21%31%17%6%
219
December1st to 10thDay
13%13%21%26%17%9%
180
11th to 20thDay
12%13%26%25%18%7%
180
21st to endDay
19%11%21%30%17%3
198
January1st to 10thNight
11%9%22%33%21%5%
760
11th to 20thNight
8%11%18%41%19%3
736
21st to endNight
10%5%22%38%20%4
792
February1st to 10thNight
10%8%19%39%21%2
720
11th to 20thNight
8%10%20%39%18%5%
704
21st to endNight
10%14%19%40%15%2
592
March1st to 10thNight
8%13%24%36%16%3
720
11th to 20thNight
11%12%18%33%23%3
720
21st to endNight
9%16%24%32%17%2
792
April1st to 10thNight
8%12%23%37%19%1
720
11th to 20thNight
12%12%19%35%19%3
711
21st to endNight
8%10%22%35%22%3
720
May1st to 10thNight
10%10%21%37%20%2
606
11th to 20thNight
7%419%41%27%3
354
21st to endNight
8%414%40%32%2
389
June1st to 10thNight
5%317%41%31%3
360
11th to 20thNight
3419%45%28%2
360
21st to endNight
4211%50%31%3
360
July1st to 10thNight
1110%49%36%2
350
11th to 20thNight
1111%52%35%
348
21st to endNight
317%44%41%5%
444
August1st to 10thNight
415%45%40%5%
537
11th to 20thNight
2214%40%37%5%
703
21st to endNight
2213%46%34%3
792
September1st to 10thNight
2214%41%36%5%
720
11th to 20thNight
4411%37%38%7%
720
21st to endNight
35%12%41%30%9%
720
October1st to 10thNight
6%5%16%39%28%7%
720
11th to 20thNight
6%6%11%40%32%5%
720
21st to endNight
7%7%14%34%28%9%
792
November1st to 10thNight
8%9%18%33%27%6%
740
11th to 20thNight
6%7%19%43%20%5%
760
21st to endNight
8%9%17%38%25%4
760
December1st to 10thNight
10%10%17%41%17%4
760
11th to 20thNight
11%11%16%40%18%4
760
21st to endNight
13%11%21%39%15%1
836
Page generated at 2024-01-11 19:33:48. Version ac07

Copyright 2024 Attilla Danko


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