Eagle's Nest
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eagle's Nest clear sky chart from 2005-11-06 to 2024-01-22.

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
34%
23466
14%
75024
10%
23417
40%
23417
17%
53802

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
12%
758
9%
2459
2%
757
20%
757
8%
1991
January11th to 20thNight
14%
760
7%
2470
4%
760
18%
760
7%
2054
January21st to endNight
17%
800
9%
2599
5%
800
22%
800
9%
2131
February1st to 10thNight
15%
720
8%
2340
4%
720
21%
720
9%
1896
February11th to 20thNight
18%
702
10%
2221
4%
700
24%
700
10%
1750
February21st to endNight
13%
592
11%
1776
3%
592
22%
592
11%
1411
March1st to 10thNight
22%
720
16%
2026
7%
720
29%
720
17%
1499
March11th to 20thNight
29%
720
18%
1980
10%
720
35%
720
20%
1409
March21st to endNight
27%
792
15%
2178
9%
792
31%
792
18%
1623
April1st to 10thNight
26%
720
13%
1944
6%
720
31%
720
19%
1415
April11th to 20thNight
28%
584
17%
1648
7%
584
35%
584
21%
1172
April21st to endNight
32%
540
16%
1620
7%
540
39%
540
22%
1108
May1st to 10thNight
36%
540
11%
1620
7%
540
39%
540
18%
1178
May11th to 20thNight
44%
531
16%
1593
11%
531
48%
531
22%
1084
May21st to endNight
55%
560
15%
1723
12%
560
60%
560
30%
1064
June1st to 10thNight
49%
360
16%
1440
17%
360
56%
360
23%
850
June11th to 20thNight
51%
360
17%
1440
19%
360
59%
360
23%
861
June21st to endNight
54%
380
17%
1460
18%
380
60%
380
23%
862
July1st to 10thNight
65%
525
15%
1575
15%
525
66%
525
31%
979
July11th to 20thNight
64%
522
17%
1566
16%
522
67%
522
34%
942
July21st to endNight
61%
591
17%
1672
15%
558
63%
558
30%
1042
August1st to 10thNight
64%
537
18%
1600
15%
534
65%
534
33%
957
August11th to 20thNight
65%
534
20%
1598
16%
534
66%
534
29%
1001
August21st to endNight
60%
620
22%
1808
16%
620
63%
620
33%
1103
September1st to 10thNight
56%
720
21%
1890
14%
720
59%
720
32%
1238
September11th to 20thNight
64%
720
27%
1980
20%
720
67%
720
37%
1196
September21st to endNight
47%
720
21%
1980
17%
720
52%
720
27%
1319
October1st to 10thNight
48%
720
18%
2101
16%
720
52%
720
28%
1344
October11th to 20thNight
31%
720
16%
2160
11%
720
40%
720
19%
1518
October21st to endNight
27%
792
16%
2376
12%
792
34%
792
16%
1743
November1st to 10thNight
35%
740
19%
2399
15%
740
43%
740
22%
1553
November11th to 20thNight
22%
760
16%
2486
9%
760
32%
760
15%
1808
November21st to endNight
21%
760
12%
2660
8%
760
28%
760
12%
2011
December1st to 10thNight
17%
760
7%
2660
4%
760
21%
760
8%
2143
December11th to 20thNight
16%
759
8%
3267
4%
759
22%
759
7%
2528
December21st to endNight
14%
827
4%
4709
3%
817
20%
817
4%
4019

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
16%10%48%6%45%5%5%7%30%
74680
Night
16%11%5%7%6%345%5%7%32%
75258
TransparencyDay
52%7%11%18%10%1
74401
Night
51%7%11%18%11%1
75056
SeeingDay
20%15%28%20%12%5%
13519
Night
20%11%28%27%12%1
23481

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
18%15%8%11%10%5%5%345%17%
1706
11th to 20thDay
18%18%8%13%9%5%444414%
1710
21st to endDay
16%18%8%13%10%35%445%13%
1791
February1st to 10thDay
18%16%6%12%9%44345%19%
1620
11th to 20thDay
16%13%6%13%8%45%5%5%5%20%
1623
21st to endDay
18%15%410%8%35%46%5%24%
1480
March1st to 10thDay
19%10%6%8%6%4445%6%27%
1934
11th to 20thDay
16%14%5%9%6%35%45%5%29%
1980
21st to endDay
22%11%6%8%6%3445%6%26%
2178
April1st to 10thDay
14%11%5%6%5%46%5%5%7%32%
2016
11th to 20thDay
18%10%47%6%35%5%5%7%31%
2276
21st to endDay
20%10%47%5%35%446%32%
2340
May1st to 10thDay
17%9%47%6%46%5%5%7%30%
2340
11th to 20thDay
18%8%37%6%345%7%7%31%
2301
21st to endDay
11%6%26%7%36%6%7%9%38%
2549
June1st to 10thDay
14%6%36%6%45%7%6%8%37%
2520
11th to 20thDay
13%7%47%6%35%6%6%9%36%
2520
21st to endDay
12%5%25%6%46%6%7%10%39%
2494
July1st to 10thDay
11%6%36%5%35%6%6%9%39%
2340
11th to 20thDay
11%6%25%6%46%6%6%9%38%
2340
21st to endDay
11%5%35%6%5%6%6%7%10%36%
2547
August1st to 10thDay
9%7%27%6%5%5%6%6%10%37%
2327
11th to 20thDay
11%7%36%7%5%6%7%7%10%33%
2303
21st to endDay
10%6%35%5%46%6%8%10%37%
2530
September1st to 10thDay
14%6%346%35%5%5%7%42%
2066
11th to 20thDay
11%5%36%6%345%6%9%42%
1980
21st to endDay
18%8%35%43445%7%39%
1980
October1st to 10thDay
15%7%35%6%35%46%8%37%
1859
11th to 20thDay
20%10%36%5%3446%5%34%
1800
21st to endDay
23%11%37%6%44447%27%
1980
November1st to 10thDay
12%9%37%5%45%447%39%
1677
11th to 20thDay
18%13%5%8%5%245%5%5%30%
1691
21st to endDay
18%15%8%8%6%35%5%5%7%21%
1520
December1st to 10thDay
19%17%8%12%7%3445%417%
1520
11th to 20thDay
18%16%7%15%6%35%446%16%
1910
21st to endDay
25%22%8%10%7%3333410%
2932
January1st to 10thNight
18%15%7%12%8%44445%20%
2459
11th to 20thNight
19%18%6%12%7%44445%17%
2470
21st to endNight
17%17%7%12%8%45%43419%
2599
February1st to 10thNight
22%14%6%10%7%44445%20%
2340
11th to 20thNight
17%14%5%10%7%46%5%45%22%
2219
21st to endNight
22%12%6%9%8%3444424%
1776
March1st to 10thNight
18%10%6%8%6%34446%32%
2026
11th to 20thNight
18%9%47%4335%6%7%34%
1980
21st to endNight
18%11%5%7%7%245%45%32%
2178
April1st to 10thNight
15%11%5%7%6%345%5%7%32%
1944
11th to 20thNight
15%10%36%5%445%5%6%35%
1648
21st to endNight
15%8%46%6%4447%7%36%
1620
May1st to 10thNight
16%9%47%6%45%5%5%7%31%
1620
11th to 20thNight
14%9%36%4345%5%8%38%
1592
21st to endNight
9%5%35%5%445%7%11%43%
1722
June1st to 10thNight
8%6%36%6%46%46%7%44%
1440
11th to 20thNight
11%6%25%5%36%5%7%8%42%
1440
21st to endNight
11%4345%45%6%7%11%41%
1460
July1st to 10thNight
8%5%36%6%445%5%8%47%
1620
11th to 20thNight
8%425%6%35%5%6%10%47%
1620
21st to endNight
8%5%35%6%35%5%7%9%43%
1771
August1st to 10thNight
7%5%25%6%445%6%9%48%
1611
11th to 20thNight
10%6%35%435%6%5%9%44%
1598
21st to endNight
9%425%5%35%6%5%7%48%
1808
September1st to 10thNight
13%5%25%5%345%5%7%46%
1890
11th to 20thNight
9%4245%3446%7%52%
1980
21st to endNight
14%7%35%6%3445%7%42%
1980
October1st to 10thNight
13%6%25%5%35%5%7%7%43%
2101
11th to 20thNight
18%8%47%5%345%5%6%35%
2160
21st to endNight
23%10%37%5%345%5%6%30%
2376
November1st to 10thNight
15%8%35%5%3445%7%40%
2399
11th to 20thNight
17%12%6%8%5%35%446%30%
2486
21st to endNight
20%14%5%7%6%35%45%6%25%
2660
December1st to 10thNight
21%17%9%8%6%34445%20%
2660
11th to 20thNight
16%18%7%11%6%3445%6%21%
3285
21st to endNight
26%20%8%9%6%34445%12%
4720

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
71%5%10%10%4
1707
11th to 20thDay
74%5%11%8%2
1710
21st to endDay
74%6%8%9%31
1791
February1st to 10thDay
70%49%12%5%1
1620
11th to 20thDay
67%6%8%12%6%
1632
21st to endDay
63%5%10%13%7%1
1480
March1st to 10thDay
57%5%12%20%6%
1934
11th to 20thDay
57%6%10%16%10%1
1980
21st to endDay
59%5%8%17%10%1
2178
April1st to 10thDay
52%6%11%18%12%1
2016
11th to 20thDay
52%6%12%15%12%2
2276
21st to endDay
52%6%11%19%10%2
2340
May1st to 10thDay
53%7%11%18%9%2
2340
11th to 20thDay
50%8%11%15%13%2
2305
21st to endDay
40%9%15%22%12%1
2549
June1st to 10thDay
43%8%12%23%13%1
2520
11th to 20thDay
43%9%14%20%13%1
2520
21st to endDay
38%9%13%23%15%2
2494
July1st to 10thDay
40%8%11%24%15%2
2275
11th to 20thDay
39%8%14%23%14%2
2271
21st to endDay
39%9%14%23%14%2
2405
August1st to 10thDay
41%10%12%25%11%1
2314
11th to 20thDay
42%11%15%22%9%2
2303
21st to endDay
39%10%13%21%13%4
2530
September1st to 10thDay
40%7%14%20%15%3
2066
11th to 20thDay
37%8%15%24%15%1
1980
21st to endDay
44%7%10%23%15%1
1980
October1st to 10thDay
43%7%12%22%14%1
1859
11th to 20thDay
51%6%11%21%10%1
1800
21st to endDay
57%6%12%15%10%1
1980
November1st to 10thDay
46%6%11%21%14%1
1677
11th to 20thDay
55%5%10%19%7%3
1691
21st to endDay
62%8%9%14%6%
1520
December1st to 10thDay
71%6%8%12%3
1520
11th to 20thDay
69%6%8%13%3
1906
21st to endDay
78%6%8%6%2
2932
January1st to 10thNight
67%6%9%12%6%
2459
11th to 20thNight
70%6%10%11%3
2470
21st to endNight
69%5%9%13%41
2599
February1st to 10thNight
67%5%9%13%5%
2340
11th to 20thNight
63%6%10%14%7%
2221
21st to endNight
64%5%8%14%8%1
1776
March1st to 10thNight
54%6%8%22%9%1
2026
11th to 20thNight
48%7%12%20%11%3
1980
21st to endNight
55%6%8%18%12%2
2178
April1st to 10thNight
50%7%10%18%14%1
1944
11th to 20thNight
48%6%12%16%15%3
1648
21st to endNight
46%6%13%17%15%2
1620
May1st to 10thNight
51%8%10%16%12%3
1620
11th to 20thNight
45%7%12%17%15%4
1593
21st to endNight
34%8%16%25%15%1
1723
June1st to 10thNight
38%7%11%25%15%3
1440
11th to 20thNight
38%8%14%21%17%2
1440
21st to endNight
35%11%13%23%17%2
1460
July1st to 10thNight
35%7%13%23%18%4
1575
11th to 20thNight
30%9%15%25%18%2
1566
21st to endNight
35%8%15%23%16%3
1672
August1st to 10thNight
32%8%15%27%18%1
1600
11th to 20thNight
35%8%15%27%12%2
1598
21st to endNight
32%9%14%24%18%4
1808
September1st to 10thNight
36%8%11%24%17%4
1890
11th to 20thNight
31%7%13%25%22%2
1980
21st to endNight
40%8%11%22%18%1
1980
October1st to 10thNight
37%8%14%21%19%1
2101
11th to 20thNight
48%7%10%21%12%1
2160
21st to endNight
54%6%11%19%9%2
2376
November1st to 10thNight
43%6%12%21%15%3
2399
11th to 20thNight
55%6%10%17%11%2
2486
21st to endNight
59%6%12%17%6%
2660
December1st to 10thNight
67%6%11%11%5%
2660
11th to 20thNight
63%7%13%14%3
3288
21st to endNight
74%7%10%8%2
4720

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
29%25%31%10%41
270
11th to 20thDay
29%23%36%9%31
270
21st to endDay
23%33%29%11%3
267
February1st to 10thDay
32%24%37%7%
240
11th to 20thDay
28%32%32%8%1
240
21st to endDay
29%31%32%8%
198
March1st to 10thDay
25%22%32%17%4
374
11th to 20thDay
29%17%32%15%6%1
420
21st to endDay
31%20%27%17%41
462
April1st to 10thDay
22%21%31%17%8%1
420
11th to 20thDay
26%20%26%15%9%4
412
21st to endDay
27%17%32%16%7%2
420
May1st to 10thDay
26%17%29%17%8%3
423
11th to 20thDay
20%13%33%22%9%4
447
21st to endDay
16%8%26%26%19%6%
485
June1st to 10thDay
14%9%30%30%13%3
450
11th to 20thDay
19%8%23%30%14%5%
450
21st to endDay
14%9%29%29%14%5%
450
July1st to 10thDay
11%5%19%30%21%13%
445
11th to 20thDay
14%6%22%29%22%8%
444
21st to endDay
12%5%25%26%22%10%
488
August1st to 10thDay
13%6%22%24%25%10%
446
11th to 20thDay
16%7%20%26%21%11%
439
21st to endDay
11%6%21%28%23%13%
495
September1st to 10thDay
16%7%20%25%20%11%
450
11th to 20thDay
10%5%19%27%27%12%
450
21st to endDay
22%10%22%23%16%6%
450
October1st to 10thDay
12%11%29%24%20%4
450
11th to 20thDay
22%16%36%18%7%1
450
21st to endDay
30%17%30%19%4
495
November1st to 10thDay
17%25%30%15%11%2
275
11th to 20thDay
28%25%27%15%41
261
21st to endDay
23%25%40%11%1
180
December1st to 10thDay
26%24%33%12%32
180
11th to 20thDay
23%28%36%12%2
180
21st to endDay
33%22%33%11%1
243
January1st to 10thNight
26%19%35%15%4
760
11th to 20thNight
32%17%31%16%3
760
21st to endNight
25%18%32%22%3
800
February1st to 10thNight
29%17%33%19%2
720
11th to 20thNight
26%17%36%19%2
703
21st to endNight
29%17%36%16%2
592
March1st to 10thNight
22%16%37%21%5%
720
11th to 20thNight
22%14%32%25%6%1
720
21st to endNight
24%10%33%24%7%1
792
April1st to 10thNight
21%13%34%25%5%1
720
11th to 20thNight
22%12%34%21%10%1
584
21st to endNight
18%9%36%30%6%1
540
May1st to 10thNight
21%8%28%32%11%1
540
11th to 20thNight
20%6%24%38%10%2
531
21st to endNight
12%322%38%22%3
562
June1st to 10thNight
8%431%39%17%1
360
11th to 20thNight
13%425%43%15%1
360
21st to endNight
12%324%41%19%1
380
July1st to 10thNight
8%313%43%29%4
525
11th to 20thNight
9%218%41%25%4
522
21st to endNight
10%315%44%27%2
591
August1st to 10thNight
9%215%42%28%3
537
11th to 20thNight
11%215%39%29%4
534
21st to endNight
10%321%32%31%4
620
September1st to 10thNight
14%5%17%33%26%5%
720
11th to 20thNight
10%315%37%31%4
720
21st to endNight
17%7%22%31%19%4
720
October1st to 10thNight
16%7%25%30%20%3
720
11th to 20thNight
23%10%30%27%9%1
720
21st to endNight
26%14%27%27%6%
792
November1st to 10thNight
20%11%28%28%12%1
740
11th to 20thNight
23%17%31%20%7%1
760
21st to endNight
28%16%31%18%7%
760
December1st to 10thNight
31%16%31%18%4
760
11th to 20thNight
25%19%33%20%3
760
21st to endNight
28%16%34%20%2
836
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