Warren Rupp Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Warren Rupp Observatory clear sky chart from 2005-11-05 to 2018-02-22.

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%
16154
16%
48907
10%
16114
40%
16114
20%
33806

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
12%
779
11%
2522
3%
776
21%
776
9%
1984
January16th to endNight
14%
832
12%
2704
5%
832
21%
832
10%
2106
February1st to 15thNight
14%
762
10%
2463
4%
761
20%
761
10%
1903
February16th to endNight
15%
659
11%
1977
3%
659
23%
659
11%
1535
March1st to 15thNight
23%
720
14%
2037
7%
720
30%
720
16%
1511
March16th to endNight
25%
768
16%
2112
9%
768
31%
768
20%
1501
April1st to 15thNight
24%
656
14%
1861
5%
656
31%
656
21%
1315
April16th to endNight
32%
540
20%
1620
7%
540
43%
540
24%
1082
May1st to 15thNight
35%
540
14%
1620
8%
540
41%
540
20%
1140
May16th to endNight
47%
561
17%
1684
13%
561
51%
561
28%
1072
June1st to 15thNight
51%
540
14%
1620
10%
540
56%
540
33%
961
June16th to endNight
52%
540
15%
1489
10%
540
57%
540
33%
940
July1st to 15thNight
59%
510
16%
1459
14%
510
61%
510
33%
919
July16th to endNight
65%
564
19%
1595
15%
531
69%
531
38%
902
August1st to 15thNight
65%
539
21%
1609
18%
536
66%
536
34%
951
August16th to endNight
66%
573
24%
1719
19%
573
70%
573
38%
970
September1st to 15thNight
58%
714
26%
1966
18%
714
62%
714
36%
1178
September16th to endNight
56%
717
27%
1980
21%
717
60%
717
33%
1214
October1st to 15thNight
45%
720
22%
2091
19%
720
51%
720
28%
1320
October16th to endNight
25%
768
21%
2331
12%
768
36%
768
20%
1599
November1st to 15thNight
34%
760
21%
2471
15%
760
43%
760
24%
1556
November16th to endNight
21%
780
16%
2543
9%
780
31%
780
15%
1828
December1st to 15thNight
16%
780
9%
2730
4%
780
23%
780
10%
2123
December16th to endNight
13%
832
9%
2704
3%
832
20%
832
8%
2196

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%9%47%6%3445%6%31%
49314
Night
14%9%46%5%3445%6%34%
49099
Cloud CoverDay
15%9%47%6%3445%7%31%
49324
Night
14%9%46%5%3445%6%34%
49103
TransparencyDay
52%310%19%11%1
49024
Night
49%311%20%12%1
48907
SeeingDay
20%11%25%20%14%7%
6021
Night
19%11%28%25%13%1
16159

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
19%14%7%10%8%34335%17%
1746
16th to endDay
14%18%8%12%8%5%433416%
1872
February1st to 15thDay
16%16%6%10%8%4433420%
1728
16th to endDay
16%15%6%10%6%24445%23%
1643
March1st to 15thDay
20%13%5%8%6%23345%24%
1912
16th to endDay
21%10%46%5%25%446%29%
2112
April1st to 15thDay
19%11%45%5%34346%30%
2095
16th to endDay
18%8%26%5%34437%35%
2340
May1st to 15thDay
21%7%36%6%35%5%45%29%
2331
16th to endDay
12%6%26%6%45%5%6%8%35%
2431
June1st to 15thDay
13%6%247%35%5%5%8%36%
2340
16th to endDay
12%5%25%6%45%6%6%9%34%
2464
July1st to 15thDay
12%7%37%5%36%45%8%35%
2406
16th to endDay
11%425%6%45%6%6%10%36%
2465
August1st to 15thDay
8%5%25%6%46%6%7%9%36%
2340
16th to endDay
9%6%26%5%35%6%6%8%39%
2477
September1st to 15thDay
14%5%35%5%3445%7%40%
1986
16th to endDay
16%6%25%5%23446%40%
1980
October1st to 15thDay
16%7%25%42345%7%37%
1869
16th to endDay
21%10%35%5%23345%34%
1892
November1st to 15thDay
13%10%36%5%2435%6%38%
1717
16th to endDay
19%13%5%6%6%24445%28%
1742
December1st to 15thDay
19%15%8%11%6%34335%19%
1560
16th to endDay
20%17%8%10%7%3324417%
1866
January1st to 15thNight
19%15%7%8%7%2434421%
2522
16th to endNight
14%16%6%8%7%45%44422%
2704
February1st to 15thNight
17%13%6%10%6%24345%23%
2461
16th to endNight
16%14%6%9%7%35%445%23%
1977
March1st to 15thNight
17%10%48%6%34445%29%
2025
16th to endNight
15%9%47%5%34446%33%
2112
April1st to 15thNight
16%8%46%5%35%45%7%32%
1861
16th to endNight
12%8%35%5%44447%38%
1620
May1st to 15thNight
17%7%36%6%35%46%7%32%
1620
16th to endNight
11%5%27%425%46%8%41%
1682
June1st to 15thNight
6%5%145%25%5%6%8%45%
1620
16th to endNight
10%424435%6%7%9%41%
1489
July1st to 15thNight
8%4245%35%47%8%45%
1548
16th to endNight
6%3235%25%5%7%10%48%
1703
August1st to 15thNight
7%4145%25%6%7%9%45%
1620
16th to endNight
8%3244245%5%8%51%
1719
September1st to 15thNight
13%424323346%51%
1966
16th to endNight
12%5%23423446%48%
1980
October1st to 15thNight
14%7%245%23446%45%
2091
16th to endNight
20%7%35%5%34446%35%
2331
November1st to 15thNight
14%8%2442445%7%40%
2471
16th to endNight
20%10%46%6%2445%6%29%
2543
December1st to 15thNight
19%16%5%9%5%24445%22%
2730
16th to endNight
19%15%8%8%6%34345%18%
2704

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
19%14%8%10%9%34335%17%
1746
16th to endDay
14%17%8%12%8%4434415%
1872
February1st to 15thDay
16%16%6%10%7%4433420%
1728
16th to endDay
16%15%6%10%6%34445%24%
1643
March1st to 15thDay
21%12%5%8%6%24346%24%
1923
16th to endDay
20%10%46%5%24436%29%
2111
April1st to 15thDay
19%11%46%5%34446%30%
2095
16th to endDay
18%8%26%5%34437%35%
2340
May1st to 15thDay
20%7%36%7%345%46%29%
2331
16th to endDay
12%5%35%6%35%5%6%9%34%
2431
June1st to 15thDay
13%6%25%6%35%5%5%8%36%
2340
16th to endDay
12%5%25%6%36%6%6%9%33%
2464
July1st to 15thDay
11%7%37%6%35%45%8%35%
2406
16th to endDay
10%5%25%6%36%6%7%10%35%
2465
August1st to 15thDay
8%426%6%46%7%6%9%36%
2340
16th to endDay
9%5%36%5%35%5%6%9%39%
2477
September1st to 15thDay
14%6%25%5%345%5%6%40%
1986
16th to endDay
16%7%35%5%24446%40%
1980
October1st to 15thDay
16%8%25%4335%6%7%37%
1869
16th to endDay
20%11%35%423345%34%
1892
November1st to 15thDay
13%9%46%5%24446%38%
1717
16th to endDay
19%13%5%7%6%24445%27%
1742
December1st to 15thDay
19%15%8%11%6%34335%18%
1560
16th to endDay
20%17%8%10%7%2333416%
1866
January1st to 15thNight
19%15%7%8%7%2444321%
2522
16th to endNight
14%15%6%8%8%34445%22%
2704
February1st to 15thNight
17%13%5%10%7%34345%24%
2454
16th to endNight
16%14%6%9%6%35%345%23%
1977
March1st to 15thNight
17%10%48%6%34346%28%
2037
16th to endNight
16%8%37%6%345%46%33%
2112
April1st to 15thNight
16%9%36%5%35%45%7%32%
1861
16th to endNight
12%9%35%6%35%45%7%38%
1620
May1st to 15thNight
17%8%36%5%45%45%7%32%
1619
16th to endNight
11%437%425%5%6%9%40%
1682
June1st to 15thNight
5%5%245%35%5%7%9%45%
1620
16th to endNight
9%424435%5%7%9%41%
1489
July1st to 15thNight
7%4245%35%5%6%8%44%
1548
16th to endNight
5%3245%25%5%7%10%48%
1703
August1st to 15thNight
6%4145%35%6%7%9%45%
1620
16th to endNight
7%4244145%5%8%50%
1719
September1st to 15thNight
12%424323346%51%
1966
16th to endNight
12%5%2442345%7%48%
1980
October1st to 15thNight
13%7%25%5%23446%45%
2091
16th to endNight
19%8%25%5%34346%35%
2331
November1st to 15thNight
14%7%25%424447%40%
2471
16th to endNight
20%10%46%6%3335%6%29%
2543
December1st to 15thNight
20%15%6%9%6%24445%21%
2730
16th to endNight
19%15%8%9%6%34445%17%
2704

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
70%38%12%5%
1747
16th to endDay
71%311%10%3
1872
February1st to 15thDay
68%37%13%6%
1730
16th to endDay
62%211%17%5%
1643
March1st to 15thDay
62%210%17%5%
1923
16th to endDay
56%210%23%7%
2112
April1st to 15thDay
55%212%16%11%
2095
16th to endDay
50%39%19%13%3
2340
May1st to 15thDay
55%311%18%9%1
2331
16th to endDay
45%6%11%22%12%1
2435
June1st to 15thDay
44%411%25%13%
2340
16th to endDay
45%5%13%19%14%1
2464
July1st to 15thDay
47%410%20%15%2
2266
16th to endDay
40%7%14%25%11%1
2310
August1st to 15thDay
40%6%11%24%14%1
2327
16th to endDay
40%412%23%14%4
2477
September1st to 15thDay
42%410%23%16%2
1986
16th to endDay
45%28%20%22%1
1980
October1st to 15thDay
45%49%22%16%
1869
16th to endDay
52%213%21%10%
1892
November1st to 15thDay
46%210%23%12%4
1717
16th to endDay
60%29%18%8%
1742
December1st to 15thDay
70%19%13%4
1560
16th to endDay
72%28%12%3
1866
January1st to 15thNight
67%28%14%6%
2522
16th to endNight
64%310%15%5%
2704
February1st to 15thNight
62%410%15%6%
2463
16th to endNight
63%38%18%6%
1977
March1st to 15thNight
56%311%19%7%1
2037
16th to endNight
51%311%22%9%1
2112
April1st to 15thNight
49%312%17%15%1
1861
16th to endNight
45%39%20%17%4
1620
May1st to 15thNight
51%410%21%11%1
1620
16th to endNight
39%5%13%23%15%2
1684
June1st to 15thNight
34%5%14%26%17%1
1620
16th to endNight
36%5%16%22%15%3
1489
July1st to 15thNight
36%5%11%23%19%3
1459
16th to endNight
29%5%16%30%15%3
1595
August1st to 15thNight
33%5%13%27%19%
1609
16th to endNight
29%5%15%26%20%3
1719
September1st to 15thNight
33%410%26%20%4
1966
16th to endNight
36%37%25%25%1
1980
October1st to 15thNight
40%310%23%19%2
2091
16th to endNight
50%29%25%10%1
2331
November1st to 15thNight
43%311%23%14%4
2471
16th to endNight
56%210%20%8%
2543
December1st to 15thNight
65%210%14%6%
2730
16th to endNight
68%311%12%2
2704

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%25%32%6%6%
135
16th to endDay
28%30%31%6%2
144
February1st to 15thDay
28%31%31%7%
135
16th to endDay
29%23%39%8%1
100
March1st to 15thDay
28%18%32%15%4
213
16th to endDay
26%14%31%17%9%
288
April1st to 15thDay
26%14%30%18%9%1
270
16th to endDay
25%10%34%12%10%7%
270
May1st to 15thDay
26%9%31%16%10%5%
288
16th to endDay
19%8%28%22%11%9%
331
June1st to 15thDay
15%6%26%28%17%5%
315
16th to endDay
17%10%27%27%13%5%
439
July1st to 15thDay
19%422%25%18%9%
370
16th to endDay
10%215%31%26%14%
326
August1st to 15thDay
12%218%29%22%16%
313
16th to endDay
12%416%27%24%15%
332
September1st to 15thDay
14%5%17%23%22%16%
315
16th to endDay
19%413%19%27%15%
314
October1st to 15thDay
16%10%23%24%20%5%
315
16th to endDay
25%13%31%21%8%
308
November1st to 15thDay
20%17%22%20%17%1
135
16th to endDay
21%23%39%12%3
132
December1st to 15thDay
15%38%28%7%5%3
90
16th to endDay
32%27%32%7%
143
January1st to 15thNight
28%21%33%13%3
780
16th to endNight
23%21%34%17%2
832
February1st to 15thNight
25%21%34%16%2
764
16th to endNight
23%18%35%18%2
659
March1st to 15thNight
24%16%31%23%4
720
16th to endNight
21%13%35%20%8%
768
April1st to 15thNight
22%14%34%21%6%
656
16th to endNight
16%9%37%24%10%2
540
May1st to 15thNight
22%7%27%30%11%1
540
16th to endNight
14%5%26%26%23%3
563
June1st to 15thNight
10%229%39%18%
540
16th to endNight
12%224%39%18%2
540
July1st to 15thNight
10%121%40%23%2
510
16th to endNight
7%117%39%29%4
564
August1st to 15thNight
9%113%43%26%6%
539
16th to endNight
9%213%34%33%6%
573
September1st to 15thNight
15%317%29%28%5%
714
16th to endNight
15%6%14%29%27%6%
717
October1st to 15thNight
18%6%23%30%19%2
720
16th to endNight
22%14%33%20%8%
768
November1st to 15thNight
19%13%29%24%11%1
760
16th to endNight
26%17%29%18%7%
780
December1st to 15thNight
29%16%31%17%4
780
16th to endNight
27%18%34%16%2
832
Page generated at 2018-02-23 11:21:38. Version ac04

Copyright 2018 A. Danko


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