White Eagle Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the White Eagle Observatory clear sky chart from 2005-11-05 to 2019-06-10.

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
37%
18353
18%
53863
11%
18311
44%
18311
24%
35834

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 15thNight
22%
1050
15%
2926
4%
1045
32%
1045
19%
2112
January16th to endNight
21%
1120
13%
3091
4%
1120
29%
1120
17%
2307
February1st to 15thNight
22%
933
14%
2584
4%
933
29%
933
18%
1873
February16th to endNight
25%
735
18%
2205
8%
735
34%
735
18%
1543
March1st to 15thNight
27%
840
15%
2520
8%
840
33%
840
18%
1745
March16th to endNight
30%
723
16%
2347
11%
723
38%
723
19%
1606
April1st to 15thNight
28%
629
16%
2097
11%
629
38%
629
20%
1412
April16th to endNight
34%
624
17%
2008
10%
624
44%
624
22%
1342
May1st to 15thNight
38%
630
16%
1862
9%
630
45%
630
22%
1293
May16th to endNight
49%
658
16%
1753
9%
657
53%
657
32%
1124
June1st to 15thNight
52%
612
18%
1632
11%
612
57%
612
37%
1014
June16th to endNight
50%
585
17%
1560
9%
585
55%
585
32%
1013
July1st to 15thNight
63%
555
19%
1480
13%
555
66%
555
41%
877
July16th to endNight
69%
612
22%
1545
16%
579
72%
579
44%
895
August1st to 15thNight
76%
575
22%
1681
21%
572
78%
572
43%
928
August16th to endNight
66%
621
21%
2070
21%
621
70%
621
36%
1140
September1st to 15thNight
64%
587
30%
1952
30%
587
69%
587
38%
1030
September16th to endNight
57%
777
26%
2145
19%
777
62%
777
37%
1278
October1st to 15thNight
45%
780
25%
2246
18%
780
52%
780
30%
1401
October16th to endNight
31%
832
20%
2642
12%
832
42%
832
23%
1702
November1st to 15thNight
31%
820
23%
2666
16%
820
42%
820
22%
1677
November16th to endNight
26%
885
18%
2775
9%
885
36%
885
20%
1868
December1st to 15thNight
25%
1050
14%
2940
6%
1050
32%
1050
18%
2147
December16th to endNight
18%
1120
11%
3136
3%
1120
26%
1120
12%
2507

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%8%36%5%3445%7%36%
54658
Night
14%8%36%5%24446%39%
54032
Cloud CoverDay
14%8%36%5%3445%7%36%
54667
Night
14%8%36%424446%40%
54037
TransparencyDay
46%5%12%22%12%1
54344
Night
44%411%22%14%2
53864
SeeingDay
17%10%26%25%14%5%
8256
Night
18%8%28%30%12%1
18357

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 15thDay
16%13%48%6%35%35%5%26%
1672
16th to endDay
13%14%6%9%7%24445%26%
1835
February1st to 15thDay
16%14%6%6%6%45%435%26%
1937
16th to endDay
18%12%38%5%33346%30%
1840
March1st to 15thDay
16%12%47%6%3445%5%29%
2090
16th to endDay
18%8%37%5%35%447%30%
2593
April1st to 15thDay
19%10%47%5%2445%5%30%
2511
16th to endDay
19%7%345%2445%7%35%
2557
May1st to 15thDay
18%8%36%5%35%45%6%30%
2746
16th to endDay
14%5%35%6%345%6%6%38%
3065
June1st to 15thDay
11%5%344345%5%7%44%
2857
16th to endDay
10%425%6%35%6%7%9%36%
2730
July1st to 15thDay
7%3246%35%5%6%9%46%
2730
16th to endDay
6%425%5%45%5%7%9%41%
2879
August1st to 15thDay
6%5%25%5%25%5%7%9%42%
2521
16th to endDay
10%5%145%345%7%10%42%
2484
September1st to 15thDay
12%424434446%49%
2324
16th to endDay
7%5%245%35%5%5%7%46%
2145
October1st to 15thDay
17%7%25%5%33347%40%
2041
16th to endDay
18%7%26%5%2335%7%37%
1934
November1st to 15thDay
16%8%36%42345%5%38%
1852
16th to endDay
18%8%47%5%33346%35%
1843
December1st to 15thDay
16%10%5%8%6%34445%29%
1680
16th to endDay
21%14%5%7%5%34335%23%
1792
January1st to 15thNight
16%12%47%5%23345%34%
2926
16th to endNight
13%11%7%8%6%34445%29%
3091
February1st to 15thNight
16%13%5%6%5%23345%33%
2582
16th to endNight
17%10%47%5%24445%33%
2205
March1st to 15thNight
15%10%46%5%35%34436%
2507
16th to endNight
17%7%36%5%34447%34%
2347
April1st to 15thNight
18%8%36%424447%35%
2097
16th to endNight
18%7%25%5%23346%38%
2008
May1st to 15thNight
16%6%246%35%45%6%36%
1862
16th to endNight
11%5%145%345%5%9%43%
1752
June1st to 15thNight
9%5%1442445%6%49%
1632
16th to endNight
9%425%5%36%5%6%10%40%
1560
July1st to 15thNight
5%3144245%6%8%52%
1560
16th to endNight
5%3224245%7%8%51%
1641
August1st to 15thNight
321434437%9%54%
1690
16th to endNight
9%3144235%48%52%
2070
September1st to 15thNight
10%313313347%56%
1952
16th to endNight
8%4144245%5%7%50%
2145
October1st to 15thNight
14%5%24423346%47%
2246
16th to endNight
19%7%25%423335%42%
2642
November1st to 15thNight
15%8%35%423345%44%
2666
16th to endNight
18%9%36%423246%37%
2775
December1st to 15thNight
20%9%38%5%24336%31%
2940
16th to endNight
22%14%5%8%6%3434423%
3136

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 15thDay
16%13%49%6%35%445%26%
1672
16th to endDay
14%14%6%8%7%23445%26%
1835
February1st to 15thDay
16%14%5%6%6%35%435%26%
1937
16th to endDay
18%12%38%5%33446%30%
1840
March1st to 15thDay
16%12%47%6%3435%5%29%
2100
16th to endDay
18%8%36%6%35%446%30%
2592
April1st to 15thDay
19%9%47%5%24445%30%
2511
16th to endDay
19%7%345%2435%7%35%
2557
May1st to 15thDay
19%8%36%5%35%45%7%30%
2746
16th to endDay
14%5%35%6%345%6%6%38%
3065
June1st to 15thDay
12%5%244345%5%7%44%
2857
16th to endDay
10%426%5%46%6%7%8%36%
2730
July1st to 15thDay
7%3245%35%5%6%9%46%
2730
16th to endDay
6%416%6%45%5%7%9%41%
2879
August1st to 15thDay
7%5%25%425%5%7%9%41%
2521
16th to endDay
10%4245%345%6%9%42%
2484
September1st to 15thDay
12%42443445%6%49%
2324
16th to endDay
8%5%24435%5%5%7%46%
2145
October1st to 15thDay
17%6%25%5%24347%40%
2041
16th to endDay
18%7%25%5%23347%37%
1934
November1st to 15thDay
16%8%36%42335%5%39%
1852
16th to endDay
18%8%47%5%23346%35%
1843
December1st to 15thDay
17%11%5%8%6%35%445%29%
1680
16th to endDay
21%14%5%7%6%34335%23%
1792
January1st to 15thNight
16%11%47%5%23345%34%
2926
16th to endNight
13%12%7%8%6%34445%29%
3091
February1st to 15thNight
16%13%5%6%5%23345%33%
2575
16th to endNight
17%10%46%5%24445%33%
2205
March1st to 15thNight
16%10%46%5%2443436%
2520
16th to endNight
17%8%36%5%35%45%6%34%
2347
April1st to 15thNight
18%7%46%424447%35%
2097
16th to endNight
18%7%25%5%23446%38%
2008
May1st to 15thNight
17%6%25%5%35%5%5%6%36%
1861
16th to endNight
11%4145%3445%9%43%
1752
June1st to 15thNight
9%5%1443346%6%49%
1632
16th to endNight
9%425%5%36%46%10%40%
1560
July1st to 15thNight
5%3144245%6%7%53%
1560
16th to endNight
5%3234246%7%9%51%
1641
August1st to 15thNight
321444437%8%54%
1690
16th to endNight
9%31442345%8%52%
2070
September1st to 15thNight
10%313313346%56%
1952
16th to endNight
8%4144245%5%7%50%
2145
October1st to 15thNight
14%424433346%47%
2246
16th to endNight
19%7%25%323335%42%
2642
November1st to 15thNight
15%8%25%324335%44%
2666
16th to endNight
18%8%36%423246%37%
2775
December1st to 15thNight
20%9%38%5%24336%31%
2940
16th to endNight
22%14%48%6%3434423%
3136

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 15thDay
59%312%15%8%
1673
16th to endDay
59%312%15%7%
1835
February1st to 15thDay
60%410%15%7%1
1939
16th to endDay
56%410%20%6%1
1840
March1st to 15thDay
56%311%20%6%
2100
16th to endDay
53%5%12%21%6%
2593
April1st to 15thDay
54%49%19%10%
2511
16th to endDay
48%413%16%12%4
2557
May1st to 15thDay
52%5%12%21%6%
2746
16th to endDay
44%5%11%22%14%2
3069
June1st to 15thDay
38%5%11%25%16%1
2857
16th to endDay
40%6%13%23%13%2
2730
July1st to 15thDay
33%6%13%27%15%3
2581
16th to endDay
35%6%16%23%14%2
2712
August1st to 15thDay
34%6%13%28%14%1
2506
16th to endDay
36%6%12%25%16%2
2484
September1st to 15thDay
35%5%10%25%18%5%
2324
16th to endDay
34%5%9%27%19%2
2145
October1st to 15thDay
44%411%23%13%2
2041
16th to endDay
46%412%22%12%2
1934
November1st to 15thDay
46%410%22%14%2
1852
16th to endDay
51%312%23%7%
1843
December1st to 15thDay
57%412%18%7%
1680
16th to endDay
63%410%14%6%
1792
January1st to 15thNight
52%311%19%12%
2926
16th to endNight
56%313%17%9%
3091
February1st to 15thNight
53%311%19%10%
2584
16th to endNight
52%311%21%9%1
2205
March1st to 15thNight
51%311%20%11%2
2520
16th to endNight
49%412%20%11%2
2347
April1st to 15thNight
48%310%22%12%1
2097
16th to endNight
46%410%20%12%5%
2008
May1st to 15thNight
46%5%12%23%10%
1862
16th to endNight
35%6%16%20%17%2
1754
June1st to 15thNight
33%5%12%26%19%2
1632
16th to endNight
38%5%13%22%17%2
1560
July1st to 15thNight
29%5%13%28%19%4
1480
16th to endNight
25%6%15%28%18%4
1545
August1st to 15thNight
25%5%16%30%19%2
1681
16th to endNight
29%5%13%28%18%4
2070
September1st to 15thNight
28%310%27%25%4
1952
16th to endNight
31%410%29%20%2
2145
October1st to 15thNight
37%49%26%19%2
2246
16th to endNight
44%310%25%15%1
2642
November1st to 15thNight
43%38%23%17%3
2666
16th to endNight
48%312%23%10%
2775
December1st to 15thNight
54%310%21%8%
2940
16th to endNight
65%39%14%6%
3136

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 15thDay
31%10%30%25%2
180
16th to endDay
18%17%33%22%5%1
192
February1st to 15thDay
30%22%34%11%1
180
16th to endDay
30%15%33%14%41
159
March1st to 15thDay
33%21%27%14%3
180
16th to endDay
26%9%31%22%7%2
360
April1st to 15thDay
24%16%28%20%8%1
390
16th to endDay
21%12%24%26%11%3
379
May1st to 15thDay
22%10%30%21%11%3
433
16th to endDay
17%12%28%21%15%4
677
June1st to 15thDay
13%5%30%31%15%4
616
16th to endDay
13%7%30%29%13%5%
570
July1st to 15thDay
8%424%29%20%11%
550
16th to endDay
7%327%31%20%10%
595
August1st to 15thDay
7%216%32%25%15%
455
16th to endDay
10%5%15%26%29%11%
396
September1st to 15thDay
12%414%31%25%11%
375
16th to endDay
8%6%19%30%27%8%
374
October1st to 15thDay
23%9%22%28%12%3
271
16th to endDay
21%18%35%18%5%
192
November1st to 15thDay
24%14%22%22%10%6%
180
16th to endDay
27%15%34%16%6%
180
December1st to 15thDay
17%24%33%14%8%
180
16th to endDay
25%21%43%6%2
192
January1st to 15thNight
21%12%36%22%6%
1050
16th to endNight
19%12%35%29%2
1120
February1st to 15thNight
23%11%33%25%5%
936
16th to endNight
22%11%34%25%5%
735
March1st to 15thNight
21%12%32%26%6%
840
16th to endNight
19%8%34%26%10%
723
April1st to 15thNight
21%12%32%26%6%
629
16th to endNight
21%7%32%27%9%
624
May1st to 15thNight
21%429%31%11%1
630
16th to endNight
12%6%25%36%18%
659
June1st to 15thNight
11%425%44%13%
612
16th to endNight
11%327%40%17%1
585
July1st to 15thNight
7%216%43%27%2
555
16th to endNight
5%115%45%29%3
612
August1st to 15thNight
418%48%31%4
575
16th to endNight
10%114%37%31%4
621
September1st to 15thNight
11%315%35%28%5%
587
16th to endNight
11%5%19%33%27%3
777
October1st to 15thNight
16%7%25%31%16%2
780
16th to endNight
23%10%30%24%10%
832
November1st to 15thNight
20%10%33%25%9%1
820
16th to endNight
21%11%34%24%7%
885
December1st to 15thNight
25%10%31%26%5%
1050
16th to endNight
29%11%32%22%4
1120
Page generated at 2019-06-10 18:29:47. Version ac04

Copyright 2019 A. Danko


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