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 2017-09-22.

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
38%
15984
18%
46897
11%
15942
45%
15942
24%
31065

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
21%
900
14%
2506
3%
895
30%
895
19%
1821
January16th to endNight
22%
960
13%
2649
4%
960
29%
960
17%
1983
February1st to 15thNight
23%
797
14%
2208
4%
797
30%
797
19%
1564
February16th to endNight
27%
631
19%
1893
8%
631
36%
631
19%
1305
March1st to 15thNight
28%
720
13%
2160
8%
720
32%
720
17%
1513
March16th to endNight
30%
619
15%
2011
11%
619
37%
619
19%
1385
April1st to 15thNight
30%
539
15%
1797
11%
539
40%
539
21%
1192
April16th to endNight
35%
540
19%
1740
11%
540
45%
540
23%
1150
May1st to 15thNight
38%
540
16%
1596
9%
540
45%
540
23%
1100
May16th to endNight
49%
562
18%
1497
10%
561
54%
561
33%
955
June1st to 15thNight
53%
540
16%
1440
11%
540
57%
540
37%
896
June16th to endNight
50%
540
17%
1440
9%
540
55%
540
33%
932
July1st to 15thNight
62%
510
17%
1360
12%
510
65%
510
40%
818
July16th to endNight
70%
564
23%
1417
17%
531
74%
531
44%
820
August1st to 15thNight
77%
539
21%
1580
20%
536
79%
536
43%
870
August16th to endNight
68%
573
22%
1910
22%
573
72%
573
36%
1041
September1st to 15thNight
64%
542
29%
1802
29%
542
69%
542
39%
944
September16th to endNight
58%
685
26%
1892
18%
685
62%
685
36%
1137
October1st to 15thNight
49%
660
27%
1900
20%
660
56%
660
33%
1136
October16th to endNight
31%
704
19%
2236
11%
704
41%
704
22%
1454
November1st to 15thNight
33%
700
24%
2276
17%
700
44%
700
25%
1390
November16th to endNight
27%
759
17%
2379
9%
759
36%
759
19%
1611
December1st to 15thNight
24%
900
13%
2520
5%
900
30%
900
17%
1863
December16th to endNight
18%
960
11%
2688
3%
960
25%
960
11%
2185

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%7%36%5%3445%7%36%
47995
Night
14%7%35%42445%6%40%
47066
Cloud CoverDay
14%7%36%5%3445%7%36%
48004
Night
14%7%35%424446%40%
47071
TransparencyDay
46%5%12%22%12%1
47681
Night
44%412%22%14%2
46898
SeeingDay
15%8%26%26%16%6%
5990
Night
18%7%28%31%13%1
15988

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%12%48%6%35%45%6%26%
1432
16th to endDay
14%14%6%9%7%24445%25%
1573
February1st to 15thDay
14%14%6%6%6%35%435%27%
1653
16th to endDay
17%11%37%5%34346%32%
1580
March1st to 15thDay
16%12%5%7%5%3445%5%29%
1790
16th to endDay
18%9%37%5%35%447%29%
2223
April1st to 15thDay
18%9%47%5%24445%31%
2151
16th to endDay
20%7%345%3445%7%34%
2220
May1st to 15thDay
19%8%35%5%35%5%5%6%29%
2352
16th to endDay
13%5%35%6%345%6%6%38%
2617
June1st to 15thDay
12%5%33435%5%5%7%44%
2520
16th to endDay
9%425%6%35%7%7%9%35%
2520
July1st to 15thDay
7%3246%35%5%6%9%44%
2520
16th to endDay
6%425%5%45%5%7%10%41%
2655
August1st to 15thDay
7%5%25%5%25%5%7%9%41%
2370
16th to endDay
9%4245%345%7%10%41%
2292
September1st to 15thDay
12%324425%446%49%
2145
16th to endDay
8%5%24435%6%5%7%44%
1881
October1st to 15thDay
14%6%25%5%33347%43%
1727
16th to endDay
19%6%25%5%2335%7%36%
1636
November1st to 15thDay
13%8%36%42345%6%41%
1582
16th to endDay
19%8%46%5%23346%35%
1580
December1st to 15thDay
18%11%5%8%6%34445%28%
1440
16th to endDay
22%14%5%7%5%34435%23%
1536
January1st to 15thNight
17%12%37%5%23345%34%
2506
16th to endNight
13%12%7%8%6%34445%29%
2649
February1st to 15thNight
15%13%46%5%23345%35%
2206
16th to endNight
15%9%47%5%2445%5%34%
1893
March1st to 15thNight
16%10%46%5%35%33436%
2147
16th to endNight
17%7%36%5%345%47%33%
2011
April1st to 15thNight
17%8%36%42445%6%36%
1797
16th to endNight
19%7%25%5%23346%38%
1740
May1st to 15thNight
17%6%245%35%5%6%6%36%
1596
16th to endNight
10%4145%345%5%9%44%
1496
June1st to 15thNight
10%5%1442445%6%50%
1440
16th to endNight
9%425%5%36%5%6%10%40%
1440
July1st to 15thNight
6%315%5%245%6%7%51%
1440
16th to endNight
5%3234246%7%9%51%
1513
August1st to 15thNight
431443437%9%53%
1589
16th to endNight
9%31342345%9%52%
1910
September1st to 15thNight
10%313313347%56%
1802
16th to endNight
8%414425%45%7%49%
1892
October1st to 15thNight
12%42432335%6%50%
1900
16th to endNight
20%7%25%423335%41%
2236
November1st to 15thNight
14%7%24423345%46%
2276
16th to endNight
18%9%36%423246%37%
2379
December1st to 15thNight
21%9%38%5%24336%30%
2520
16th to endNight
24%14%5%7%6%3434421%
2688

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%12%48%6%35%446%25%
1432
16th to endDay
14%15%7%8%8%24445%25%
1573
February1st to 15thDay
14%14%6%6%6%35%435%27%
1653
16th to endDay
17%11%37%5%33446%32%
1580
March1st to 15thDay
16%12%5%6%5%3445%6%29%
1800
16th to endDay
18%8%36%6%35%447%30%
2222
April1st to 15thDay
19%9%5%7%424445%31%
2151
16th to endDay
20%7%345%2435%7%34%
2220
May1st to 15thDay
20%8%36%5%35%5%5%7%29%
2352
16th to endDay
14%5%35%6%35%5%6%6%38%
2617
June1st to 15thDay
12%5%244345%5%7%44%
2520
16th to endDay
10%5%26%5%46%7%7%9%36%
2520
July1st to 15thDay
8%3246%35%5%6%9%44%
2520
16th to endDay
6%415%5%45%6%7%10%41%
2655
August1st to 15thDay
7%5%25%5%25%5%7%9%41%
2370
16th to endDay
10%4245%345%7%10%41%
2292
September1st to 15thDay
12%32443445%6%49%
2145
16th to endDay
8%5%24435%5%5%7%44%
1881
October1st to 15thDay
15%5%25%5%24347%44%
1727
16th to endDay
19%7%25%5%23347%36%
1636
November1st to 15thDay
14%8%36%42335%6%41%
1582
16th to endDay
19%8%47%5%23346%35%
1580
December1st to 15thDay
18%11%5%8%5%35%435%28%
1440
16th to endDay
22%14%5%7%6%23435%23%
1536
January1st to 15thNight
17%11%47%5%23345%34%
2506
16th to endNight
13%12%7%8%6%34445%29%
2649
February1st to 15thNight
15%12%46%5%23345%35%
2199
16th to endNight
16%10%46%5%2445%5%34%
1893
March1st to 15thNight
17%10%46%425%43435%
2160
16th to endNight
17%7%36%5%35%45%7%33%
2011
April1st to 15thNight
17%7%46%424447%36%
1797
16th to endNight
19%7%26%422346%39%
1740
May1st to 15thNight
17%6%15%435%5%6%7%35%
1595
16th to endNight
10%4145%345%5%9%44%
1496
June1st to 15thNight
10%5%1443345%6%50%
1440
16th to endNight
9%4245%37%47%10%40%
1440
July1st to 15thNight
6%3145%245%6%7%52%
1440
16th to endNight
5%3234246%7%9%51%
1513
August1st to 15thNight
421443437%8%54%
1589
16th to endNight
9%31342345%9%52%
1910
September1st to 15thNight
10%31331335%7%56%
1802
16th to endNight
8%5%145%25%5%5%7%49%
1892
October1st to 15thNight
12%424323347%50%
1900
16th to endNight
20%7%25%323335%41%
2236
November1st to 15thNight
14%6%24433335%46%
2276
16th to endNight
18%8%46%423246%37%
2379
December1st to 15thNight
21%9%48%424336%30%
2520
16th to endNight
24%14%5%8%5%3433421%
2688

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
58%413%14%9%
1433
16th to endDay
61%312%15%6%
1573
February1st to 15thDay
58%411%15%8%1
1655
16th to endDay
53%412%21%6%1
1580
March1st to 15thDay
55%313%19%6%
1800
16th to endDay
53%5%13%20%6%
2223
April1st to 15thDay
53%49%20%11%
2151
16th to endDay
49%414%16%11%3
2220
May1st to 15thDay
52%6%12%22%6%
2352
16th to endDay
43%5%11%21%14%2
2621
June1st to 15thDay
38%5%11%25%18%1
2520
16th to endDay
40%6%13%21%14%2
2520
July1st to 15thDay
34%6%13%27%14%2
2371
16th to endDay
35%6%17%23%14%2
2488
August1st to 15thDay
35%6%13%27%14%1
2355
16th to endDay
36%6%12%25%16%2
2292
September1st to 15thDay
34%5%10%26%19%4
2145
16th to endDay
35%5%9%29%17%2
1881
October1st to 15thDay
40%411%26%15%1
1727
16th to endDay
47%413%23%9%2
1636
November1st to 15thDay
42%5%10%23%15%2
1582
16th to endDay
51%312%23%7%
1580
December1st to 15thDay
58%412%17%6%
1440
16th to endDay
64%49%12%7%
1536
January1st to 15thNight
53%312%19%10%
2506
16th to endNight
57%313%16%8%
2649
February1st to 15thNight
51%312%21%9%
2208
16th to endNight
50%312%22%9%1
1893
March1st to 15thNight
52%312%18%10%2
2160
16th to endNight
50%413%20%9%1
2011
April1st to 15thNight
47%310%22%13%1
1797
16th to endNight
46%310%22%12%4
1740
May1st to 15thNight
46%5%11%24%11%
1596
16th to endNight
34%7%15%20%18%3
1498
June1st to 15thNight
33%5%12%25%19%3
1440
16th to endNight
37%5%13%21%18%2
1440
July1st to 15thNight
30%5%12%28%19%2
1360
16th to endNight
25%6%16%27%19%4
1417
August1st to 15thNight
25%5%16%30%18%2
1580
16th to endNight
28%5%13%27%18%5%
1910
September1st to 15thNight
28%310%28%26%3
1802
16th to endNight
32%5%11%29%18%2
1892
October1st to 15thNight
33%49%28%21%1
1900
16th to endNight
44%310%25%13%1
2236
November1st to 15thNight
40%39%24%18%4
2276
16th to endNight
49%312%22%11%
2379
December1st to 15thNight
55%311%20%8%
2520
16th to endNight
67%38%13%5%
2688

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
27%11%33%24%3
90
16th to endDay
15%13%34%27%8%1
96
February1st to 15thDay
18%27%38%13%1
90
16th to endDay
23%13%34%17%8%2
81
March1st to 15thDay
40%15%24%15%4
90
16th to endDay
30%8%29%20%8%2
240
April1st to 15thDay
22%13%29%22%10%1
270
16th to endDay
20%10%25%27%10%5%
270
May1st to 15thDay
23%9%30%21%11%3
309
16th to endDay
16%11%29%22%15%4
517
June1st to 15thDay
12%5%29%31%15%4
495
16th to endDay
12%7%33%26%13%5%
495
July1st to 15thDay
9%5%26%29%17%11%
475
16th to endDay
7%226%30%21%11%
515
August1st to 15thDay
8%215%33%26%14%
403
16th to endDay
9%5%14%28%29%13%
332
September1st to 15thDay
10%5%15%32%26%9%
315
16th to endDay
9%417%29%29%9%
278
October1st to 15thDay
13%6%22%31%19%5%
167
16th to endDay
22%16%35%22%2
96
November1st to 15thDay
11%12%24%32%12%7%
90
16th to endDay
35%11%33%12%7%
90
December1st to 15thDay
22%22%33%13%7%1
90
16th to endDay
27%25%42%32
96
January1st to 15thNight
21%12%37%22%5%
900
16th to endNight
19%11%34%31%3
960
February1st to 15thNight
21%10%35%25%6%
800
16th to endNight
20%11%34%26%6%
631
March1st to 15thNight
22%11%31%27%6%
720
16th to endNight
19%9%34%26%9%1
619
April1st to 15thNight
20%11%31%28%7%
539
16th to endNight
22%5%33%28%9%
540
May1st to 15thNight
21%428%32%11%1
540
16th to endNight
12%5%26%37%17%
563
June1st to 15thNight
12%424%44%13%
540
16th to endNight
10%327%38%18%
540
July1st to 15thNight
8%217%44%25%1
510
16th to endNight
5%15%45%29%3
564
August1st to 15thNight
418%49%31%5%
539
16th to endNight
9%113%38%32%4
573
September1st to 15thNight
11%215%36%29%4
542
16th to endNight
11%5%17%34%27%3
685
October1st to 15thNight
15%5%24%32%18%2
660
16th to endNight
24%10%30%25%10%
704
November1st to 15thNight
17%10%34%26%10%1
700
16th to endNight
21%11%32%25%8%
759
December1st to 15thNight
27%10%30%26%5%
900
16th to endNight
30%11%31%22%4
960
Page generated at 2017-09-23 05:43:46. Version ac04

Copyright 2017 A. Danko


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