Big Cigar Astronomy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Big Cigar Astronomy clear sky chart from 2005-11-06 to 2024-10-24.

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
36%
25517
8%
95477
4%
25296
39%
25296
6%
77559

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
24%
940
7%
4392
2%
926
29%
926
4%
3573
January11th to 20thNight
19%
949
6%
4378
1%
930
23%
930
3%
3764
January21st to endNight
22%
1038
3%
4709
2%
1023
24%
1023
3%
4143
February1st to 10thNight
23%
950
6%
2470
2%
950
26%
950
6%
2225
February11th to 20thNight
26%
773
8%
2252
3%
773
29%
773
6%
1964
February21st to endNight
21%
628
7%
1884
2%
628
26%
628
6%
1643
March1st to 10thNight
26%
757
13%
3687
2%
745
29%
745
3%
2681
March11th to 20thNight
32%
675
15%
3607
4%
660
36%
660
4%
2381
March21st to endNight
28%
625
4%
3434
4%
605
32%
605
3%
2834
April1st to 10thNight
24%
570
6%
1900
3%
570
30%
570
4%
1693
April11th to 20thNight
29%
563
5%
1875
3%
563
32%
563
5%
1659
April21st to endNight
30%
570
5%
1831
3%
570
34%
570
7%
1579
May1st to 10thNight
32%
566
12%
2726
3%
559
34%
559
4%
2018
May11th to 20thNight
38%
550
7%
2456
1%
541
41%
541
4%
1777
May21st to endNight
45%
608
6%
2711
2%
593
48%
593
6%
1901
June1st to 10thNight
54%
570
6%
1520
4%
570
55%
570
10%
1295
June11th to 20thNight
48%
570
5%
1520
3%
570
49%
570
8%
1331
June21st to endNight
50%
570
5%
1520
3%
570
52%
570
9%
1310
July1st to 10thNight
70%
546
7%
2441
5%
535
72%
535
8%
1892
July11th to 20thNight
61%
541
8%
2207
5%
533
63%
533
10%
1472
July21st to endNight
66%
605
9%
2489
7%
569
68%
569
9%
1798
August1st to 10thNight
70%
554
15%
2326
8%
545
71%
545
8%
1646
August11th to 20thNight
66%
553
8%
2785
7%
543
68%
543
6%
2089
August21st to endNight
64%
612
8%
3117
7%
605
67%
605
6%
2217
September1st to 10thNight
59%
570
11%
1900
11%
570
61%
570
10%
1537
September11th to 20thNight
59%
629
11%
1959
12%
629
59%
629
11%
1579
September21st to endNight
48%
760
10%
2090
6%
760
51%
760
9%
1781
October1st to 10thNight
43%
760
9%
2209
5%
760
46%
760
8%
1880
October11th to 20thNight
34%
760
10%
2280
5%
760
38%
760
9%
1894
October21st to endNight
29%
805
6%
2589
3%
805
33%
805
6%
2261
November1st to 10thNight
31%
740
9%
2406
6%
740
36%
740
6%
2043
November11th to 20thNight
25%
760
9%
2470
5%
760
30%
760
6%
2106
November21st to endNight
26%
912
7%
2622
3%
912
29%
912
6%
2304
December1st to 10thNight
21%
950
5%
2660
2%
950
24%
950
5%
2396
December11th to 20thNight
22%
949
7%
3210
2%
948
26%
948
5%
2704
December21st to endNight
16%
1039
3%
4845
1%
1026
20%
1026
3%
4189

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
13%9%38%5%4446%7%37%
101311
Night
14%10%47%44435%6%39%
97529
TransparencyDay
24%49%6%13%7%1
101099
Night
25%49%6%12%7%1
97413
SeeingDay
18%9%28%26%14%5%
15833
Night
18%7%30%32%12%1
25657

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
12%14%10%13%6%45%34425%
2527
11th to 20thDay
12%12%5%16%5%35%8%7%5%19%
2530
21st to endDay
16%18%10%12%5%43345%20%
2915
February1st to 10thDay
11%15%5%8%5%5%6%46%6%28%
1710
11th to 20thDay
14%10%37%6%6%4346%37%
1814
21st to endDay
13%13%5%9%6%4435%6%32%
1570
March1st to 10thDay
13%9%47%44435%6%41%
3120
11th to 20thDay
11%6%38%5%4446%7%42%
3320
21st to endDay
21%13%410%5%5%435%5%24%
4148
April1st to 10thDay
19%12%48%5%43446%30%
2280
11th to 20thDay
17%10%37%5%3435%7%34%
2254
21st to endDay
20%9%47%5%4345%6%32%
2347
May1st to 10thDay
17%7%38%5%4445%6%36%
4141
11th to 20thDay
15%7%25%44435%7%44%
4399
21st to endDay
13%6%26%445%47%8%39%
4824
June1st to 10thDay
11%5%26%4445%6%8%44%
2660
11th to 20thDay
11%6%25%45%446%8%44%
2660
21st to endDay
12%6%36%5%45%5%8%9%38%
2660
July1st to 10thDay
12%8%28%45%5%5%8%10%33%
4440
11th to 20thDay
6%425%445%46%9%51%
4440
21st to endDay
9%6%27%5%6%5%46%9%42%
4813
August1st to 10thDay
10%5%26%45%6%47%9%41%
4366
11th to 20thDay
12%5%26%34446%9%45%
3762
21st to endDay
10%6%26%44445%8%47%
4180
September1st to 10thDay
12%5%25%44435%8%47%
2280
11th to 20thDay
12%41443336%8%51%
2201
21st to endDay
12%7%28%5%4435%7%44%
2090
October1st to 10thDay
14%6%25%433346%48%
1969
11th to 20thDay
20%10%26%443346%36%
1900
21st to endDay
20%10%37%433345%37%
1833
November1st to 10thDay
12%9%35%43445%5%45%
1672
11th to 20thDay
14%12%49%5%35%45%6%33%
1710
21st to endDay
17%13%49%5%32346%36%
1555
December1st to 10thDay
14%14%310%5%5%5%346%29%
1520
11th to 20thDay
13%15%5%10%5%45%45%6%28%
1918
21st to endDay
19%20%9%14%6%4433314%
2783
January1st to 10thNight
12%14%9%12%6%4324431%
4428
11th to 20thNight
13%16%8%14%6%446%6%420%
4440
21st to endNight
17%18%8%12%5%5%4245%20%
4750
February1st to 10thNight
13%14%49%5%5%4345%33%
2470
11th to 20thNight
12%11%38%5%44346%39%
2251
21st to endNight
17%12%48%333346%36%
1884
March1st to 10thNight
18%9%35%443345%42%
3733
11th to 20thNight
9%7%26%5%5%445%8%46%
3655
21st to endNight
24%11%49%434235%29%
3481
April1st to 10thNight
18%9%36%5%44346%38%
1900
11th to 20thNight
19%9%37%444345%38%
1875
21st to endNight
18%8%27%44445%7%38%
1831
May1st to 10thNight
17%6%36%44446%8%37%
2752
11th to 20thNight
14%6%26%445%5%6%7%40%
2506
21st to endNight
11%8%26%44445%7%43%
2743
June1st to 10thNight
9%415%5%45%47%8%46%
1520
11th to 20thNight
11%5%25%34436%10%47%
1520
21st to endNight
11%7%26%43446%7%46%
1520
July1st to 10thNight
15%7%26%445%45%8%40%
2530
11th to 20thNight
5%424445%46%8%55%
2530
21st to endNight
7%5%25%5%5%5%5%6%8%46%
2750
August1st to 10thNight
8%425%44445%8%52%
2570
11th to 20thNight
10%6%26%34436%7%50%
3066
21st to endNight
9%5%2443435%9%51%
3476
September1st to 10thNight
9%5%35%434246%55%
1900
11th to 20thNight
11%425%34435%8%53%
1959
21st to endNight
11%6%25%44435%7%50%
2090
October1st to 10thNight
12%6%26%434346%51%
2209
11th to 20thNight
18%8%26%343246%44%
2280
21st to endNight
20%9%26%43435%6%38%
2589
November1st to 10thNight
12%8%26%33335%6%48%
2406
11th to 20thNight
14%11%47%45%436%5%36%
2470
21st to endNight
17%11%47%43335%6%37%
2622
December1st to 10thNight
15%13%49%5%5%5%35%6%31%
2660
11th to 20thNight
15%15%49%5%45%45%5%30%
3279
21st to endNight
22%18%6%10%5%4445%5%18%
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
43%38%6%9%3
2528
11th to 20thDay
38%40%9%8%6%
2530
21st to endDay
44%40%5%9%2
2915
February1st to 10thDay
19%64%5%5%6%
1710
11th to 20thDay
18%63%211%5%1
1824
21st to endDay
18%65%39%41
1570
March1st to 10thDay
24%43%5%18%8%3
3120
11th to 20thDay
22%43%6%22%8%
3320
21st to endDay
38%44%7%8%2
4148
April1st to 10thDay
22%65%37%3
2280
11th to 20thDay
18%65%47%5%1
2254
21st to endDay
17%65%46%7%1
2347
May1st to 10thDay
26%43%6%13%11%
4179
11th to 20thDay
23%42%6%20%9%
4403
21st to endDay
20%43%9%14%11%3
4837
June1st to 10thDay
11%65%5%12%7%1
2660
11th to 20thDay
16%65%5%8%5%1
2660
21st to endDay
15%64%6%10%5%1
2660
July1st to 10thDay
33%39%8%15%5%1
4371
11th to 20thDay
17%38%11%23%11%
4365
21st to endDay
25%38%9%11%15%2
4662
August1st to 10thDay
25%39%10%18%8%
4351
11th to 20thDay
22%40%8%23%7%
3798
21st to endDay
24%38%9%18%11%
4179
September1st to 10thDay
16%61%5%11%7%
2280
11th to 20thDay
11%60%5%14%9%2
2201
21st to endDay
18%59%411%7%1
2090
October1st to 10thDay
18%60%412%5%
1969
11th to 20thDay
18%60%311%8%
1900
21st to endDay
22%61%47%5%1
1833
November1st to 10thDay
20%59%5%8%7%1
1672
11th to 20thDay
20%60%49%6%1
1710
21st to endDay
24%59%5%9%3
1555
December1st to 10thDay
23%60%6%6%41
1520
11th to 20thDay
26%49%9%9%5%2
1915
21st to endDay
54%37%343
2783
January1st to 10thNight
38%38%6%12%6%1
4428
11th to 20thNight
44%38%5%7%5%
4440
21st to endNight
44%40%48%3
4750
February1st to 10thNight
19%65%45%6%1
2470
11th to 20thNight
17%63%311%6%
2252
21st to endNight
16%64%29%43
1884
March1st to 10thNight
27%42%5%16%6%4
3733
11th to 20thNight
19%42%5%21%11%1
3655
21st to endNight
38%41%411%6%1
3481
April1st to 10thNight
19%65%38%41
1900
11th to 20thNight
18%65%26%8%1
1875
21st to endNight
15%64%49%7%1
1831
May1st to 10thNight
26%43%7%10%12%2
2779
11th to 20thNight
23%45%8%17%6%1
2507
21st to endNight
21%44%7%10%13%4
2751
June1st to 10thNight
10%66%5%10%8%1
1520
11th to 20thNight
14%66%310%6%1
1520
21st to endNight
14%64%5%10%7%1
1520
July1st to 10thNight
33%37%10%12%6%3
2490
11th to 20thNight
15%38%11%25%11%
2482
21st to endNight
22%39%9%12%16%2
2662
August1st to 10thNight
21%38%9%18%14%
2561
11th to 20thNight
24%39%7%21%9%
3096
21st to endNight
20%39%9%20%10%1
3476
September1st to 10thNight
12%61%6%12%9%
1900
11th to 20thNight
12%60%5%14%7%3
1959
21st to endNight
16%60%412%8%
2090
October1st to 10thNight
18%59%411%7%1
2209
11th to 20thNight
16%59%412%9%1
2280
21st to endNight
20%62%49%5%
2589
November1st to 10thNight
20%58%49%7%1
2406
11th to 20thNight
19%60%310%7%1
2470
21st to endNight
22%59%5%9%41
2622
December1st to 10thNight
24%60%47%41
2660
11th to 20thNight
27%50%6%10%6%1
3281
21st to endNight
44%39%6%8%3
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
20%11%30%28%10%1
270
11th to 20thDay
21%13%36%25%41
270
21st to endDay
23%9%34%27%5%1
297
February1st to 10thDay
17%16%40%21%5%1
270
11th to 20thDay
18%19%37%21%41
270
21st to endDay
23%17%41%16%3
225
March1st to 10thDay
15%21%40%17%7%
270
11th to 20thDay
25%16%33%18%7%1
270
21st to endDay
29%12%29%22%5%3
489
April1st to 10thDay
28%11%34%22%5%
460
11th to 20thDay
24%17%28%19%10%2
452
21st to endDay
25%11%28%23%11%2
460
May1st to 10thDay
22%12%30%24%9%2
496
11th to 20thDay
23%6%30%25%12%3
675
21st to endDay
17%8%27%26%15%6%
734
June1st to 10thDay
11%6%29%30%17%5%
680
11th to 20thDay
12%7%29%30%17%5%
680
21st to endDay
15%6%28%29%16%5%
680
July1st to 10thDay
10%317%32%24%14%
671
11th to 20thDay
9%427%29%20%10%
668
21st to endDay
8%323%35%22%9%
739
August1st to 10thDay
9%318%33%24%12%
676
11th to 20thDay
11%317%27%25%15%
500
21st to endDay
12%416%34%24%9%
539
September1st to 10thDay
15%5%22%26%24%7%
490
11th to 20thDay
12%219%31%24%11%
490
21st to endDay
15%10%25%26%17%7%
490
October1st to 10thDay
18%7%27%26%18%4
369
11th to 20thDay
27%14%32%20%7%1
300
21st to endDay
30%12%30%21%6%1
306
November1st to 10thDay
18%14%37%20%9%2
270
11th to 20thDay
22%14%37%20%6%1
270
21st to endDay
28%7%37%21%6%
270
December1st to 10thDay
20%16%37%18%7%2
270
11th to 20thDay
20%9%40%21%10%1
270
21st to endDay
28%13%38%19%2
297
January1st to 10thNight
18%11%36%27%7%
950
11th to 20thNight
22%11%35%25%6%1
950
21st to endNight
21%9%34%30%7%
1045
February1st to 10thNight
21%9%36%27%6%
950
11th to 20thNight
19%12%35%29%5%
776
21st to endNight
24%12%37%22%4
628
March1st to 10thNight
21%10%35%26%7%
760
11th to 20thNight
16%11%33%31%9%
680
21st to endNight
25%8%30%29%6%1
627
April1st to 10thNight
23%10%37%25%4
570
11th to 20thNight
23%10%32%29%6%
563
21st to endNight
23%7%32%28%9%1
570
May1st to 10thNight
19%8%33%33%7%1
570
11th to 20thNight
20%428%36%12%
561
21st to endNight
15%5%25%39%15%1
617
June1st to 10thNight
10%326%46%15%1
570
11th to 20thNight
13%231%41%12%1
570
21st to endNight
13%425%42%17%1
570
July1st to 10thNight
9%112%44%31%2
555
11th to 20thNight
9%120%42%25%3
552
21st to endNight
8%116%50%24%2
624
August1st to 10thNight
6%113%50%27%4
567
11th to 20thNight
9%215%39%31%5%
564
21st to endNight
10%115%44%26%3
627
September1st to 10thNight
10%320%38%24%5%
570
11th to 20thNight
12%220%36%26%3
629
21st to endNight
13%6%26%32%21%2
760
October1st to 10thNight
14%5%30%33%16%2
760
11th to 20thNight
22%10%28%31%9%1
760
21st to endNight
25%8%32%26%8%
805
November1st to 10thNight
16%9%37%25%11%1
740
11th to 20thNight
21%13%35%25%7%
760
21st to endNight
23%10%33%27%7%
912
December1st to 10thNight
23%11%36%24%6%
950
11th to 20thNight
24%9%34%26%7%1
950
21st to endNight
30%9%34%23%3
1045
Page generated at 2024-10-21 01:20:05. Version ac07

Copyright © 2024 Attilla Danko.


Big Cigar Astronomy Clear Sky Chart |Charts Home