Yarger Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Yarger Observatory clear sky chart from 2005-11-05 to

2017-09-12
.

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%
15907
16%
46754
11%
15865
43%
15865
21%
32466

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
17%
900
9%
2506
4%
895
21%
895
12%
2016
January16th to endNight
19%
954
8%
2682
4%
954
23%
954
11%
2189
February1st to 15thNight
19%
701
9%
2169
3%
701
24%
701
12%
1666
February16th to endNight
25%
631
13%
1893
6%
631
31%
631
14%
1439
March1st to 15thNight
29%
720
14%
2138
9%
720
34%
720
19%
1528
March16th to endNight
32%
726
17%
2070
10%
726
39%
726
21%
1453
April1st to 15thNight
31%
539
15%
1797
10%
539
39%
539
20%
1215
April16th to endNight
36%
540
21%
1657
12%
540
45%
540
24%
1091
May1st to 15thNight
37%
540
14%
1620
7%
540
44%
540
22%
1111
May16th to endNight
50%
562
16%
1583
11%
561
54%
561
31%
995
June1st to 15thNight
54%
540
17%
1440
12%
540
59%
540
38%
886
June16th to endNight
60%
540
15%
1440
11%
540
63%
540
36%
895
July1st to 15thNight
66%
510
17%
1360
15%
510
67%
510
42%
798
July16th to endNight
68%
564
21%
1423
17%
531
71%
531
41%
829
August1st to 15thNight
73%
539
23%
1609
19%
536
75%
536
40%
890
August16th to endNight
65%
573
21%
1850
20%
573
69%
573
32%
1075
September1st to 15thNight
63%
596
27%
1833
24%
596
67%
596
37%
1045
September16th to endNight
58%
657
26%
1815
20%
657
61%
657
35%
1106
October1st to 15thNight
50%
660
26%
1834
19%
660
56%
660
31%
1159
October16th to endNight
27%
704
17%
2280
10%
704
36%
704
18%
1567
November1st to 15thNight
34%
700
21%
2276
16%
700
42%
700
23%
1469
November16th to endNight
26%
720
13%
2340
10%
720
30%
720
13%
1767
December1st to 15thNight
16%
831
8%
2451
3%
831
21%
831
10%
2003
December16th to endNight
15%
960
7%
2688
2%
960
20%
960
8%
2274

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%46%5%3445%7%33%
47913
Night
15%9%46%5%34446%34%
46924
Cloud CoverDay
14%8%46%5%35%45%7%33%
47922
Night
15%9%46%5%34446%34%
46929
TransparencyDay
49%311%21%12%1
47601
Night
50%310%21%12%1
46754
SeeingDay
16%6%24%26%18%7%
5910
Night
20%6%26%31%13%1
15911

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
18%18%6%9%8%45%43416%
1432
16th to endDay
12%18%12%12%10%5%5%22412%
1541
February1st to 15thDay
13%14%8%12%9%5%6%445%17%
1691
16th to endDay
16%12%7%12%7%45%445%18%
1580
March1st to 15thDay
17%12%6%8%6%35%45%6%25%
1811
16th to endDay
19%9%36%6%34446%31%
2163
April1st to 15thDay
20%12%35%433346%32%
2151
16th to endDay
17%8%25%42435%6%38%
2302
May1st to 15thDay
21%7%36%5%3445%7%31%
2331
16th to endDay
12%5%25%6%35%5%5%7%40%
2530
June1st to 15thDay
10%5%26%5%3445%7%43%
2520
16th to endDay
9%4245%36%6%8%8%39%
2520
July1st to 15thDay
7%5%245%346%5%9%45%
2520
16th to endDay
7%4245%35%6%7%10%42%
2648
August1st to 15thDay
6%4245%45%6%7%9%43%
2340
16th to endDay
11%425%5%345%5%8%42%
2351
September1st to 15thDay
13%4244245%48%45%
2035
16th to endDay
12%5%245%35%47%9%40%
1815
October1st to 15thDay
14%6%27%5%34446%39%
1796
16th to endDay
22%8%36%6%34347%30%
1592
November1st to 15thDay
14%9%345%2436%6%38%
1582
16th to endDay
20%16%6%8%6%34445%21%
1620
December1st to 15thDay
16%18%11%9%6%2333419%
1506
16th to endDay
21%16%8%12%7%2344413%
1536
January1st to 15thNight
20%14%6%9%6%34445%19%
2506
16th to endNight
15%14%8%10%9%45%445%16%
2682
February1st to 15thNight
17%12%6%10%7%3435%6%22%
2167
16th to endNight
16%10%6%11%6%35%5%5%424%
1893
March1st to 15thNight
16%10%47%434436%33%
2125
16th to endNight
17%6%46%6%25%446%34%
2070
April1st to 15thNight
19%8%345%35%448%33%
1797
16th to endNight
18%6%15%425%45%5%39%
1657
May1st to 15thNight
19%8%25%5%3445%7%34%
1620
16th to endNight
12%6%2432445%7%44%
1581
June1st to 15thNight
10%42443345%8%47%
1440
16th to endNight
8%5%235%245%7%10%43%
1440
July1st to 15thNight
5%315%425%5%5%8%52%
1440
16th to endNight
6%31342445%9%53%
1519
August1st to 15thNight
6%3134345%7%7%52%
1620
16th to endNight
10%325%425%447%49%
1850
September1st to 15thNight
12%31433235%6%52%
1833
16th to endNight
12%5%24424446%48%
1815
October1st to 15thNight
14%6%14423446%46%
1834
16th to endNight
23%9%35%423335%35%
2280
November1st to 15thNight
15%8%35%5%2335%6%39%
2276
16th to endNight
20%15%48%5%2435%6%23%
2340
December1st to 15thNight
21%16%9%8%7%3334418%
2451
16th to endNight
23%16%7%9%7%35%445%13%
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
18%18%5%9%8%445%4415%
1432
16th to endDay
13%17%11%12%10%5%5%325%12%
1541
February1st to 15thDay
13%13%8%12%8%6%6%43417%
1691
16th to endDay
15%12%8%12%7%45%445%17%
1580
March1st to 15thDay
17%11%6%8%5%35%45%6%25%
1821
16th to endDay
18%9%36%6%34446%30%
2162
April1st to 15thDay
20%11%45%433346%32%
2151
16th to endDay
17%8%25%42435%6%38%
2302
May1st to 15thDay
20%8%26%44445%7%31%
2331
16th to endDay
12%5%25%5%35%5%6%7%40%
2530
June1st to 15thDay
10%5%26%4345%6%8%43%
2520
16th to endDay
9%425%5%46%5%7%9%39%
2520
July1st to 15thDay
6%425%5%35%6%5%9%45%
2520
16th to endDay
6%4245%36%5%7%10%42%
2648
August1st to 15thDay
6%4245%45%6%6%9%43%
2340
16th to endDay
11%425%5%25%5%6%7%42%
2351
September1st to 15thDay
12%5%24424447%45%
2035
16th to endDay
12%5%245%3446%8%40%
1815
October1st to 15thDay
14%6%26%5%34447%39%
1796
16th to endDay
22%7%36%5%44346%30%
1592
November1st to 15thDay
14%9%345%3435%6%38%
1582
16th to endDay
20%15%6%7%6%34345%21%
1620
December1st to 15thDay
16%18%10%9%6%2343419%
1506
16th to endDay
21%16%8%11%7%2445%413%
1536
January1st to 15thNight
20%14%7%9%6%34445%19%
2506
16th to endNight
14%14%8%11%9%45%446%16%
2682
February1st to 15thNight
16%12%6%10%7%3435%7%22%
2160
16th to endNight
16%10%6%10%6%345%5%5%24%
1893
March1st to 15thNight
17%10%47%434436%33%
2138
16th to endNight
17%6%47%6%35%446%34%
2070
April1st to 15thNight
19%8%346%245%48%32%
1797
16th to endNight
18%7%15%425%45%6%39%
1657
May1st to 15thNight
18%8%26%43445%7%33%
1619
16th to endNight
12%5%24425%5%5%8%43%
1581
June1st to 15thNight
10%42443435%9%46%
1440
16th to endNight
7%5%235%345%6%10%43%
1440
July1st to 15thNight
5%315%425%45%9%52%
1440
16th to endNight
5%3135%3435%9%53%
1519
August1st to 15thNight
5%3144345%6%9%51%
1620
16th to endNight
10%325%424448%48%
1850
September1st to 15thNight
12%313322446%52%
1833
16th to endNight
12%5%24424437%48%
1815
October1st to 15thNight
14%6%15%423446%46%
1834
16th to endNight
23%8%26%423335%35%
2280
November1st to 15thNight
15%8%35%5%23346%38%
2276
16th to endNight
19%14%5%7%5%3445%5%24%
2340
December1st to 15thNight
20%16%9%7%7%3433418%
2451
16th to endNight
23%16%6%9%6%45%44413%
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
71%312%9%3
1433
16th to endDay
75%29%8%3
1541
February1st to 15thDay
68%37%13%5%1
1693
16th to endDay
67%39%14%5%
1580
March1st to 15thDay
59%312%16%7%
1821
16th to endDay
55%212%22%6%
2163
April1st to 15thDay
53%39%20%13%
2151
16th to endDay
46%213%20%13%3
2302
May1st to 15thDay
52%311%22%9%
2331
16th to endDay
41%411%27%13%1
2534
June1st to 15thDay
38%310%27%18%1
2520
16th to endDay
38%5%13%22%17%2
2520
July1st to 15thDay
36%410%25%20%3
2371
16th to endDay
33%414%27%17%2
2481
August1st to 15thDay
34%414%27%17%2
2327
16th to endDay
39%311%25%16%3
2351
September1st to 15thDay
37%211%25%19%2
2035
16th to endDay
39%38%28%18%
1815
October1st to 15thDay
44%211%25%15%1
1796
16th to endDay
53%212%20%9%
1592
November1st to 15thDay
45%210%23%15%1
1582
16th to endDay
65%210%18%3
1620
December1st to 15thDay
68%18%15%3
1506
16th to endDay
73%311%9%2
1536
January1st to 15thNight
66%29%14%5%
2506
16th to endNight
68%311%13%2
2682
February1st to 15thNight
62%211%16%5%1
2169
16th to endNight
61%210%19%5%
1893
March1st to 15thNight
53%311%18%10%1
2138
16th to endNight
51%312%23%8%1
2070
April1st to 15thNight
50%29%21%15%
1797
16th to endNight
46%28%21%16%3
1657
May1st to 15thNight
49%311%22%11%1
1620
16th to endNight
39%314%25%14%2
1583
June1st to 15thNight
34%311%30%18%1
1440
16th to endNight
35%419%22%16%2
1440
July1st to 15thNight
29%314%28%20%3
1360
16th to endNight
28%5%15%25%21%3
1423
August1st to 15thNight
28%412%29%22%2
1609
16th to endNight
35%39%24%22%4
1850
September1st to 15thNight
32%39%28%23%3
1833
16th to endNight
36%26%29%22%1
1815
October1st to 15thNight
39%38%27%20%1
1834
16th to endNight
52%19%24%10%
2280
November1st to 15thNight
46%29%23%14%2
2276
16th to endNight
61%312%17%5%
2340
December1st to 15thNight
70%28%14%4
2451
16th to endNight
73%39%11%2
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
22%11%40%16%10%
90
16th to endDay
25%6%39%22%5%1
96
February1st to 15thDay
20%16%40%15%7%
90
16th to endDay
18%11%39%19%9%1
81
March1st to 15thDay
28%18%24%25%3
111
16th to endDay
30%5%29%22%10%1
288
April1st to 15thDay
27%6%28%26%8%2
270
16th to endDay
20%7%31%20%14%4
270
May1st to 15thDay
26%6%24%23%12%5%
288
16th to endDay
16%6%26%27%15%7%
430
June1st to 15thDay
11%426%32%18%6%
495
16th to endDay
11%5%31%27%17%7%
495
July1st to 15thDay
10%224%26%23%12%
475
16th to endDay
7%216%34%26%12%
508
August1st to 15thDay
7%112%26%31%19%
313
16th to endDay
12%312%26%28%15%
332
September1st to 15thDay
14%115%25%28%14%
299
16th to endDay
16%5%11%23%31%11%
254
October1st to 15thDay
16%8%20%29%19%5%
255
16th to endDay
21%8%37%26%5%
104
November1st to 15thDay
7%7%28%32%15%7%
90
16th to endDay
24%10%45%14%5%
90
December1st to 15thDay
23%22%34%14%5%
90
16th to endDay
23%23%44%5%2
96
January1st to 15thNight
27%11%34%21%4
900
16th to endNight
20%10%34%29%4
954
February1st to 15thNight
24%9%36%25%4
704
16th to endNight
22%9%32%29%6%
631
March1st to 15thNight
24%8%31%26%8%
720
16th to endNight
21%7%29%32%7%
726
April1st to 15thNight
23%7%30%30%7%
539
16th to endNight
22%5%31%30%8%1
540
May1st to 15thNight
23%325%34%11%
540
16th to endNight
16%222%38%17%1
563
June1st to 15thNight
12%122%44%17%
540
16th to endNight
9%120%43%23%1
540
July1st to 15thNight
9%14%46%26%2
510
16th to endNight
7%112%39%35%3
564
August1st to 15thNight
7%19%47%29%5%
539
16th to endNight
11%111%32%36%6%
573
September1st to 15thNight
15%113%34%29%5%
596
16th to endNight
17%215%31%28%4
657
October1st to 15thNight
18%421%35%19%1
660
16th to endNight
26%9%31%24%8%
704
November1st to 15thNight
22%7%30%27%11%1
700
16th to endNight
28%8%28%26%7%
720
December1st to 15thNight
29%10%31%23%4
831
16th to endNight
31%9%33%20%4
960
Page generated at 2017-09-13 07:39:18. Version ac04

Copyright 2017 A. Danko


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