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 2018-03-11.

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%
16683
16%
49053
11%
16641
42%
16641
21%
34160

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
16%
975
9%
2716
3%
970
21%
970
11%
2202
January16th to endNight
19%
1033
9%
2905
4%
1033
23%
1033
12%
2352
February1st to 15thNight
18%
761
10%
2354
4%
761
24%
761
12%
1814
February16th to endNight
24%
683
13%
2049
6%
683
30%
683
14%
1566
March1st to 15thNight
29%
764
14%
2270
9%
764
34%
764
19%
1613
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%
609
27%
1869
24%
609
66%
609
36%
1069
September16th to endNight
59%
717
28%
1980
21%
717
63%
717
36%
1189
October1st to 15thNight
49%
720
24%
2001
18%
720
55%
720
29%
1297
October16th to endNight
28%
768
18%
2487
12%
768
37%
768
19%
1707
November1st to 15thNight
33%
760
20%
2471
16%
760
41%
760
22%
1615
November16th to endNight
26%
780
14%
2535
10%
780
31%
780
14%
1885
December1st to 15thNight
17%
900
7%
2655
3%
900
21%
900
10%
2153
December16th to endNight
15%
1040
7%
2912
2%
1040
20%
1040
8%
2460

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%9%46%6%3445%7%33%
49581
Night
15%9%46%5%34446%34%
49223
Cloud CoverDay
14%8%46%6%35%45%7%33%
49590
Night
15%9%46%5%34446%34%
49228
TransparencyDay
49%311%21%12%1
49269
Night
50%310%21%12%1
49053
SeeingDay
17%6%25%25%17%7%
6485
Night
20%6%26%31%13%1
16687

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%9%45%43415%
1552
16th to endDay
13%18%11%11%9%5%5%325%13%
1670
February1st to 15thDay
14%13%7%12%9%5%5%43417%
1836
16th to endDay
17%12%7%12%7%45%445%18%
1710
March1st to 15thDay
16%12%6%8%6%35%45%6%25%
1916
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%47%45%
2079
16th to endDay
11%5%245%25%46%9%41%
1980
October1st to 15thDay
15%6%27%5%35%446%38%
1959
16th to endDay
21%8%36%6%34347%29%
1736
November1st to 15thDay
16%9%345%2436%6%37%
1717
16th to endDay
19%16%5%8%6%33345%23%
1755
December1st to 15thDay
15%18%10%9%7%23335%19%
1631
16th to endDay
20%16%8%12%8%2344413%
1664
January1st to 15thNight
20%14%6%9%8%34445%18%
2716
16th to endNight
14%14%8%10%9%45%445%17%
2905
February1st to 15thNight
17%13%6%9%7%3435%6%22%
2352
16th to endNight
18%10%6%10%6%35%44424%
2049
March1st to 15thNight
16%10%47%434435%34%
2257
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%
1869
16th to endNight
12%5%14424447%49%
1980
October1st to 15thNight
15%6%15%423446%44%
2001
16th to endNight
22%9%36%42333435%
2487
November1st to 15thNight
16%9%36%6%2335%6%37%
2471
16th to endNight
19%15%48%5%24346%25%
2535
December1st to 15thNight
20%16%9%8%7%3334418%
2655
16th to endNight
22%16%7%9%7%35%445%13%
2912

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%9%45%5%4415%
1552
16th to endDay
13%18%10%11%9%5%4325%13%
1670
February1st to 15thDay
14%13%8%12%8%5%5%43417%
1836
16th to endDay
16%12%7%12%7%45%445%18%
1710
March1st to 15thDay
16%11%6%8%5%35%45%6%25%
1926
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%
2079
16th to endDay
11%5%245%3446%9%42%
1980
October1st to 15thDay
14%6%26%5%3445%7%38%
1959
16th to endDay
21%7%36%6%44346%30%
1736
November1st to 15thDay
15%9%445%3435%6%36%
1717
16th to endDay
19%15%6%7%6%34345%23%
1755
December1st to 15thDay
15%18%10%9%6%3343419%
1631
16th to endDay
20%16%8%11%8%2435%412%
1664
January1st to 15thNight
20%13%7%9%8%35%445%18%
2716
16th to endNight
14%13%8%11%8%45%446%17%
2905
February1st to 15thNight
16%13%6%10%7%3435%6%22%
2345
16th to endNight
18%10%6%10%6%34445%24%
2049
March1st to 15thNight
17%10%47%434436%33%
2270
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
11%413423446%52%
1869
16th to endNight
12%5%14324437%49%
1980
October1st to 15thNight
14%6%16%423446%44%
2001
16th to endNight
22%9%36%423335%35%
2487
November1st to 15thNight
16%8%36%5%2335%6%37%
2471
16th to endNight
18%14%5%7%5%34446%25%
2535
December1st to 15thNight
19%16%8%8%8%3433418%
2655
16th to endNight
22%16%6%10%7%45%44413%
2912

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%311%9%3
1553
16th to endDay
74%210%8%3
1670
February1st to 15thDay
69%37%13%5%
1838
16th to endDay
67%39%14%5%
1710
March1st to 15thDay
58%312%16%8%
1926
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
38%211%25%19%2
2079
16th to endDay
37%39%28%19%1
1980
October1st to 15thDay
45%211%24%14%2
1959
16th to endDay
54%212%20%9%
1736
November1st to 15thDay
46%210%23%14%1
1717
16th to endDay
63%210%18%4
1755
December1st to 15thDay
68%18%16%4
1631
16th to endDay
74%311%8%2
1664
January1st to 15thNight
67%39%14%5%
2716
16th to endNight
67%312%13%3
2905
February1st to 15thNight
63%211%16%5%
2354
16th to endNight
62%29%18%5%
2049
March1st to 15thNight
53%311%19%10%1
2270
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
1869
16th to endNight
34%27%30%22%1
1980
October1st to 15thNight
41%37%26%19%1
2001
16th to endNight
52%29%25%10%
2487
November1st to 15thNight
47%210%23%13%2
2471
16th to endNight
60%312%18%5%
2535
December1st to 15thNight
69%28%14%5%
2655
16th to endNight
73%39%11%2
2912

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
24%8%34%21%11%
135
16th to endDay
25%8%40%20%4
144
February1st to 15thDay
25%15%35%17%5%
135
16th to endDay
25%13%39%15%6%
120
March1st to 15thDay
24%18%26%24%5%
142
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%114%25%28%15%
315
16th to endDay
14%5%11%21%33%12%
314
October1st to 15thDay
18%7%20%29%19%4
315
16th to endDay
21%11%33%28%5%
152
November1st to 15thDay
17%7%28%27%13%5%
135
16th to endDay
23%11%41%17%5%
135
December1st to 15thDay
20%21%35%14%7%
135
16th to endDay
22%20%44%10%2
144
January1st to 15thNight
27%10%34%22%4
975
16th to endNight
20%10%35%29%4
1033
February1st to 15thNight
24%8%36%25%4
764
16th to endNight
24%9%32%27%6%
683
March1st to 15thNight
23%8%31%26%8%
764
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%6%
609
16th to endNight
16%215%31%28%5%
717
October1st to 15thNight
19%420%35%18%1
720
16th to endNight
26%9%30%24%8%
768
November1st to 15thNight
22%7%30%27%11%1
760
16th to endNight
27%8%29%27%6%
780
December1st to 15thNight
28%11%32%23%5%
900
16th to endNight
31%9%34%21%4
1040
Page generated at 2018-03-12 13:28:04. Version ac04

Copyright 2018 A. Danko


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