EyeScope Star Shack
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the EyeScope Star Shack clear sky chart from 2005-11-06 to 2024-03-08.

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
30%
24530
10%
81193
7%
24432
34%
24432
13%
62968

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
9%
946
2%
4419
1%
926
11%
926
2%
3938
January11th to 20thNight
12%
947
2%
4439
2%
930
14%
930
3%
4100
January21st to endNight
14%
1034
2%
4884
2%
1023
15%
1023
3%
4461
February1st to 10thNight
15%
849
5%
2559
3%
849
17%
849
6%
2235
February11th to 20thNight
19%
739
8%
2237
3%
739
24%
739
9%
1830
February21st to endNight
19%
628
8%
1884
2%
628
25%
628
10%
1513
March1st to 10thNight
30%
751
16%
2251
10%
751
36%
751
20%
1573
March11th to 20thNight
27%
720
18%
2029
8%
720
35%
720
20%
1475
March21st to endNight
34%
737
17%
2123
11%
737
40%
737
21%
1497
April1st to 10thNight
26%
540
12%
1800
8%
540
32%
540
14%
1325
April11th to 20thNight
33%
533
18%
1670
12%
533
41%
533
19%
1168
April21st to endNight
36%
540
15%
1620
8%
540
43%
540
21%
1133
May1st to 10thNight
40%
540
14%
1620
9%
540
45%
540
21%
1117
May11th to 20thNight
40%
531
15%
1506
11%
531
44%
531
21%
1059
May21st to endNight
52%
583
14%
1552
10%
582
56%
582
32%
990
June1st to 10thNight
47%
388
14%
1288
11%
388
53%
388
25%
806
June11th to 20thNight
53%
360
15%
1260
14%
360
57%
360
26%
764
June21st to endNight
51%
393
15%
1293
12%
393
55%
393
28%
784
July1st to 10thNight
61%
525
16%
1400
11%
525
63%
525
40%
831
July11th to 20thNight
58%
522
17%
1392
12%
522
61%
522
34%
865
July21st to endNight
59%
591
16%
1487
13%
558
61%
558
36%
922
August1st to 10thNight
62%
537
17%
1512
14%
534
64%
534
35%
900
August11th to 20thNight
63%
534
19%
1598
15%
534
66%
534
33%
945
August21st to endNight
52%
594
16%
1864
14%
594
55%
594
26%
1165
September1st to 10thNight
53%
548
17%
1808
15%
548
56%
548
28%
1097
September11th to 20thNight
49%
720
21%
1980
15%
720
53%
720
30%
1290
September21st to endNight
45%
720
16%
1980
12%
720
48%
720
23%
1394
October1st to 10thNight
38%
720
16%
1980
11%
720
43%
720
22%
1404
October11th to 20thNight
23%
720
9%
2258
5%
720
28%
720
11%
1786
October21st to endNight
20%
792
10%
2574
7%
792
25%
792
9%
2108
November1st to 10thNight
23%
740
13%
2406
10%
740
29%
740
13%
1838
November11th to 20thNight
16%
760
9%
2470
6%
760
20%
760
7%
2058
November21st to endNight
11%
810
5%
2643
3%
810
14%
810
5%
2326
December1st to 10thNight
10%
950
2%
2850
1%
950
11%
950
4%
2581
December11th to 20thNight
9%
950
2%
3522
1%
949
11%
949
4%
3143
December21st to endNight
8%
1038
2%
5035
0%
1026
10%
1026
2%
4547

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
15%11%5%8%6%3445%6%32%
78202
Night
16%14%6%11%8%34445%25%
81385
TransparencyDay
55%5%12%19%9%1
77908
Night
62%5%10%15%7%1
81214
SeeingDay
19%12%28%25%12%3
14664
Night
21%11%28%28%11%1
24560

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
12%25%16%20%8%342225%
2527
11th to 20thDay
13%18%10%18%19%7%42324
2530
21st to endDay
16%22%11%15%9%45%3338%
2783
February1st to 10thDay
10%17%9%14%15%6%5%345%13%
1620
11th to 20thDay
13%13%8%14%11%45%44419%
1826
21st to endDay
13%14%7%11%10%45%5%45%23%
1570
March1st to 10thDay
12%10%5%8%8%5%45%47%31%
1868
11th to 20thDay
10%11%6%7%6%45%446%36%
1930
21st to endDay
17%10%5%7%6%34447%33%
2250
April1st to 10thDay
20%12%48%5%34446%29%
2160
11th to 20thDay
20%11%45%43345%5%36%
2238
21st to endDay
16%10%47%5%35%5%5%6%34%
2340
May1st to 10thDay
15%8%35%5%3445%6%41%
2340
11th to 20thDay
14%7%35%5%345%47%42%
2387
21st to endDay
12%5%244345%6%9%46%
2725
June1st to 10thDay
13%5%25%5%245%6%9%45%
2668
11th to 20thDay
12%5%25%5%35%5%6%9%43%
2700
21st to endDay
14%7%245%3445%8%43%
2661
July1st to 10thDay
8%42342446%9%54%
2520
11th to 20thDay
11%42433446%8%50%
2520
21st to endDay
9%5%24425%46%9%50%
2743
August1st to 10thDay
10%5%245%346%7%9%46%
2415
11th to 20thDay
12%5%25%5%35%5%6%8%47%
2303
21st to endDay
14%6%25%4345%5%7%46%
2489
September1st to 10thDay
16%6%245%3445%7%44%
2134
11th to 20thDay
15%5%26%5%3345%7%45%
1980
21st to endDay
18%7%35%5%35%5%6%9%35%
1980
October1st to 10thDay
21%9%37%5%4335%7%33%
1980
11th to 20thDay
26%15%5%9%7%44435%18%
1696
21st to endDay
25%18%5%8%8%44445%16%
1782
November1st to 10thDay
18%19%5%8%434446%25%
1672
11th to 20thDay
15%24%9%12%7%35%445%14%
1710
21st to endDay
19%24%10%13%6%3333313%
1532
December1st to 10thDay
15%24%16%17%6%332338%
1330
11th to 20thDay
16%22%10%17%10%433338%
1671
21st to endDay
21%22%11%15%9%333347%
2622
January1st to 10thNight
13%23%10%21%10%332239%
4428
11th to 20thNight
12%17%8%21%20%5%33228%
4440
21st to endNight
16%23%10%16%11%443337%
4884
February1st to 10thNight
11%17%8%15%16%46%33313%
2559
11th to 20thNight
12%13%7%15%11%5%5%445%18%
2237
21st to endNight
15%17%6%11%8%45%445%21%
1884
March1st to 10thNight
13%10%5%8%7%44445%36%
2240
11th to 20thNight
13%10%5%10%7%345%6%434%
2029
21st to endNight
16%9%46%7%35%5%5%6%34%
2123
April1st to 10thNight
21%10%5%8%6%35%5%45%28%
1800
11th to 20thNight
19%9%47%6%3445%5%35%
1670
21st to endNight
18%9%37%6%25%446%36%
1620
May1st to 10thNight
14%9%38%6%36%5%5%7%34%
1620
11th to 20thNight
14%10%46%7%46%45%6%35%
1506
21st to endNight
12%5%35%5%35%46%9%44%
1551
June1st to 10thNight
14%6%25%6%35%45%8%41%
1288
11th to 20thNight
11%5%26%5%35%6%6%8%41%
1260
21st to endNight
12%6%25%7%34448%46%
1293
July1st to 10thNight
10%424415%5%7%9%50%
1440
11th to 20thNight
8%6%35%6%35%5%5%7%48%
1440
21st to endNight
8%5%25%435%5%6%9%49%
1575
August1st to 10thNight
7%5%25%6%345%6%9%49%
1521
11th to 20thNight
10%415%5%35%46%8%48%
1598
21st to endNight
14%6%25%5%336%46%45%
1864
September1st to 10thNight
13%5%35%5%3445%6%47%
1808
11th to 20thNight
17%6%25%43445%7%44%
1980
21st to endNight
20%6%36%5%3446%7%35%
1980
October1st to 10thNight
19%10%46%444445%36%
1980
11th to 20thNight
25%13%48%7%35%445%22%
2258
21st to endNight
29%15%48%7%3443419%
2574
November1st to 10thNight
19%17%5%8%6%33346%25%
2406
11th to 20thNight
17%23%7%10%8%34335%17%
2470
21st to endNight
18%24%10%12%7%3443312%
2643
December1st to 10thNight
15%26%14%16%7%243239%
2850
11th to 20thNight
15%20%10%20%9%4333311%
3526
21st to endNight
22%21%11%14%7%334349%
5040

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
88%3341
2528
11th to 20thDay
87%4441
2530
21st to endDay
82%6%7%41
2783
February1st to 10thDay
75%5%8%10%2
1620
11th to 20thDay
69%5%10%10%5%
1836
21st to endDay
65%410%17%4
1570
March1st to 10thDay
55%5%13%18%9%1
1870
11th to 20thDay
52%412%23%6%2
1930
21st to endDay
53%5%11%20%9%1
2250
April1st to 10thDay
58%411%17%9%
2160
11th to 20thDay
52%310%21%14%1
2238
21st to endDay
51%5%11%16%14%3
2340
May1st to 10thDay
45%412%24%13%3
2340
11th to 20thDay
44%5%11%23%15%3
2391
21st to endDay
37%5%15%27%14%2
2725
June1st to 10thDay
37%5%14%27%15%2
2668
11th to 20thDay
39%5%14%25%17%1
2700
21st to endDay
41%415%25%14%1
2661
July1st to 10thDay
28%5%16%31%19%2
2451
11th to 20thDay
33%5%14%31%16%2
2445
21st to endDay
34%5%15%29%17%1
2591
August1st to 10thDay
36%6%18%28%11%1
2400
11th to 20thDay
36%6%16%29%12%1
2303
21st to endDay
39%5%15%26%13%1
2489
September1st to 10thDay
40%5%13%25%16%1
2134
11th to 20thDay
39%5%16%30%9%1
1980
21st to endDay
46%6%15%24%9%
1980
October1st to 10thDay
52%5%11%23%8%1
1980
11th to 20thDay
69%5%10%13%3
1696
21st to endDay
71%5%11%10%2
1782
November1st to 10thDay
61%410%19%6%
1672
11th to 20thDay
74%411%8%4
1710
21st to endDay
77%410%7%1
1532
December1st to 10thDay
84%35%6%1
1330
11th to 20thDay
82%6%6%5%1
1671
21st to endDay
84%47%42
2622
January1st to 10thNight
82%47%6%1
4428
11th to 20thNight
84%5%5%41
4440
21st to endNight
83%5%7%41
4884
February1st to 10thNight
77%46%9%31
2559
11th to 20thNight
69%5%10%14%3
2238
21st to endNight
65%5%10%14%6%
1884
March1st to 10thNight
51%413%22%10%
2251
11th to 20thNight
52%5%10%20%11%2
2030
21st to endNight
50%411%21%13%1
2123
April1st to 10thNight
58%5%8%18%11%1
1800
11th to 20thNight
52%38%21%13%3
1670
21st to endNight
50%5%9%19%15%2
1620
May1st to 10thNight
49%5%11%20%12%4
1620
11th to 20thNight
50%49%20%15%2
1507
21st to endNight
38%5%14%26%14%4
1552
June1st to 10thNight
41%5%11%26%16%1
1288
11th to 20thNight
37%7%13%25%15%3
1260
21st to endNight
39%5%14%25%16%2
1293
July1st to 10thNight
30%5%15%30%17%3
1400
11th to 20thNight
34%6%14%26%19%1
1392
21st to endNight
33%6%18%26%16%1
1487
August1st to 10thNight
33%6%20%30%11%1
1512
11th to 20thNight
33%6%17%29%15%1
1598
21st to endNight
40%6%14%24%15%1
1864
September1st to 10thNight
37%6%13%24%19%1
1808
11th to 20thNight
39%6%16%30%10%1
1980
21st to endNight
48%5%16%23%8%
1980
October1st to 10thNight
49%5%11%23%11%1
1980
11th to 20thNight
63%6%10%15%5%
2258
21st to endNight
69%5%8%14%4
2574
November1st to 10thNight
60%6%11%17%6%1
2406
11th to 20thNight
71%410%10%41
2470
21st to endNight
77%6%10%7%1
2643
December1st to 10thNight
83%37%6%1
2850
11th to 20thNight
80%6%9%42
3525
21st to endNight
81%7%8%41
5040

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
21%16%40%17%5%1
270
11th to 20thDay
23%18%36%17%41
270
21st to endDay
24%15%34%21%5%
297
February1st to 10thDay
21%26%35%11%5%1
270
11th to 20thDay
18%26%35%18%31
270
21st to endDay
21%26%41%11%2
225
March1st to 10thDay
18%23%37%18%4
261
11th to 20thDay
20%14%34%23%9%1
370
21st to endDay
27%12%27%24%9%1
462
April1st to 10thDay
26%12%31%22%7%2
420
11th to 20thDay
28%16%25%18%12%1
412
21st to endDay
20%14%28%24%11%2
420
May1st to 10thDay
21%17%26%22%12%3
423
11th to 20thDay
16%9%36%27%8%4
533
21st to endDay
14%10%27%30%15%3
679
June1st to 10thDay
14%8%30%31%14%2
630
11th to 20thDay
16%7%27%33%14%3
630
21st to endDay
17%6%27%33%16%3
630
July1st to 10thDay
9%6%26%33%19%6%
621
11th to 20thDay
12%8%24%34%16%6%
618
21st to endDay
11%6%26%34%18%4
684
August1st to 10thDay
10%422%32%23%8%
534
11th to 20thDay
13%5%18%34%19%10%
439
21st to endDay
18%8%19%31%19%5%
495
September1st to 10thDay
18%9%24%23%20%6%
450
11th to 20thDay
13%8%22%30%20%6%
450
21st to endDay
18%12%20%27%18%5%
450
October1st to 10thDay
25%13%26%20%14%2
450
11th to 20thDay
32%16%28%19%41
342
21st to endDay
32%18%29%16%41
297
November1st to 10thDay
29%15%31%19%6%
270
11th to 20thDay
21%25%33%17%3
270
21st to endDay
25%30%28%13%4
210
December1st to 10thDay
31%19%30%14%5%1
180
11th to 20thDay
24%27%34%12%21
180
21st to endDay
31%28%32%8%21
252
January1st to 10thNight
22%17%33%21%6%1
950
11th to 20thNight
23%17%31%23%6%
950
21st to endNight
21%12%33%27%6%
1045
February1st to 10thNight
19%17%33%24%5%1
849
11th to 20thNight
19%17%32%26%6%
743
21st to endNight
24%15%32%24%4
628
March1st to 10thNight
17%10%35%27%10%1
751
11th to 20thNight
19%11%35%28%7%
720
21st to endNight
20%9%29%33%9%1
737
April1st to 10thNight
25%10%30%28%6%1
540
11th to 20thNight
24%8%29%28%10%1
533
21st to endNight
20%9%29%33%9%1
540
May1st to 10thNight
16%7%29%36%11%1
540
11th to 20thNight
18%8%27%35%11%1
531
21st to endNight
15%423%36%20%1
584
June1st to 10thNight
16%425%39%15%1
388
11th to 20thNight
11%424%43%18%1
360
21st to endNight
13%5%22%39%19%1
393
July1st to 10thNight
12%218%45%20%3
525
11th to 20thNight
11%419%37%26%3
522
21st to endNight
10%221%39%25%2
591
August1st to 10thNight
10%318%42%26%1
537
11th to 20thNight
10%5%15%36%31%3
534
21st to endNight
17%6%18%36%22%2
594
September1st to 10thNight
14%324%33%22%3
548
11th to 20thNight
19%421%31%21%4
720
21st to endNight
23%7%19%31%16%3
720
October1st to 10thNight
24%10%23%29%13%1
720
11th to 20thNight
32%12%27%22%7%1
720
21st to endNight
35%14%25%21%5%1
792
November1st to 10thNight
28%14%29%22%6%1
740
11th to 20thNight
27%18%31%20%4
760
21st to endNight
30%18%30%18%4
810
December1st to 10thNight
26%21%32%18%3
950
11th to 20thNight
23%21%35%16%41
950
21st to endNight
30%15%34%18%3
1045
Page generated at 2024-03-05 07:24:02. Version ac07

Copyright © 2024 Attilla Danko.


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