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 2005-11-06 to 2024-01-31.

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
33%
23953
16%
74810
10%
23900
40%
23900
19%
51980

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 10thNight
12%
759
13%
2459
4%
757
23%
757
9%
1928
January11th to 20thNight
11%
760
9%
2470
3%
760
18%
760
8%
2004
January21st to endNight
15%
835
11%
2711
5%
835
21%
835
9%
2162
February1st to 10thNight
12%
720
9%
2340
4%
720
18%
720
10%
1846
February11th to 20thNight
16%
701
12%
2158
5%
700
23%
700
11%
1650
February21st to endNight
12%
592
13%
1776
2%
592
22%
592
10%
1385
March1st to 10thNight
21%
720
15%
2065
7%
720
29%
720
16%
1500
March11th to 20thNight
24%
720
20%
1980
9%
720
33%
720
21%
1368
March21st to endNight
23%
792
17%
2178
8%
792
30%
792
18%
1583
April1st to 10thNight
24%
716
15%
1976
6%
716
30%
716
21%
1371
April11th to 20thNight
29%
533
20%
1609
9%
533
39%
533
22%
1084
April21st to endNight
26%
540
18%
1620
5%
540
36%
540
21%
1094
May1st to 10thNight
30%
540
13%
1620
6%
540
36%
540
19%
1154
May11th to 20thNight
37%
531
17%
1592
10%
531
43%
531
22%
1068
May21st to endNight
53%
582
16%
1745
13%
582
57%
582
32%
1073
June1st to 10thNight
49%
540
14%
1620
11%
540
53%
540
30%
1002
June11th to 20thNight
51%
540
17%
1604
12%
540
57%
540
31%
966
June21st to endNight
50%
540
19%
1440
12%
540
57%
540
35%
913
July1st to 10thNight
61%
525
16%
1468
14%
525
64%
525
34%
922
July11th to 20thNight
62%
522
19%
1566
15%
522
66%
522
35%
900
July21st to endNight
62%
591
20%
1672
17%
558
65%
558
33%
1013
August1st to 10thNight
64%
537
20%
1600
16%
534
66%
534
34%
947
August11th to 20thNight
61%
534
22%
1598
18%
534
64%
534
32%
968
August21st to endNight
63%
594
25%
1782
19%
594
67%
594
38%
1008
September1st to 10thNight
56%
708
23%
1955
16%
708
59%
708
34%
1190
September11th to 20thNight
63%
720
30%
1980
23%
720
66%
720
41%
1136
September21st to endNight
46%
720
25%
1980
17%
720
53%
720
30%
1252
October1st to 10thNight
45%
720
23%
2056
18%
720
52%
720
31%
1265
October11th to 20thNight
31%
720
21%
2160
12%
720
42%
720
22%
1445
October21st to endNight
25%
792
20%
2415
12%
792
35%
792
17%
1699
November1st to 10thNight
33%
740
22%
2406
15%
740
43%
740
24%
1487
November11th to 20thNight
23%
760
19%
2470
9%
760
37%
760
17%
1712
November21st to endNight
22%
760
15%
2482
9%
760
30%
760
14%
1801
December1st to 10thNight
15%
760
10%
2660
4%
760
22%
760
9%
2085
December11th to 20thNight
16%
759
12%
3086
5%
758
24%
758
9%
2290
December21st to endNight
13%
830
6%
4511
4%
817
20%
817
5%
3709

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
15%10%47%6%35%5%5%7%31%
75016
Night
15%10%47%6%3445%7%34%
75088
TransparencyDay
53%411%20%11%1
74738
Night
51%311%21%12%2
74886
SeeingDay
21%15%28%20%11%5%
13929
Night
20%12%28%26%12%2
23965

By Month

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 10thDay
17%15%8%10%9%45%45%6%18%
1706
11th to 20thDay
17%18%10%11%9%45%335%15%
1710
21st to endDay
16%18%10%13%8%4443415%
1872
February1st to 10thDay
19%17%6%9%8%5%3335%21%
1620
11th to 20thDay
15%14%6%13%8%45%5%5%5%22%
1687
21st to endDay
17%15%6%10%6%34346%27%
1480
March1st to 10thDay
18%11%6%8%7%34446%28%
1894
11th to 20thDay
17%14%5%8%6%245%5%7%27%
1980
21st to endDay
23%11%48%6%34446%27%
2178
April1st to 10thDay
14%13%5%7%6%4445%7%31%
1999
11th to 20thDay
17%11%47%5%3445%6%34%
2298
21st to endDay
21%9%27%6%45%5%47%32%
2340
May1st to 10thDay
18%9%37%8%45%6%5%6%30%
2340
11th to 20thDay
20%8%36%6%345%6%8%30%
2301
21st to endDay
10%5%37%6%47%7%7%9%35%
2531
June1st to 10thDay
13%6%36%6%36%5%7%8%36%
2340
11th to 20thDay
11%8%35%7%46%6%6%9%35%
2345
21st to endDay
11%5%26%6%46%6%7%9%37%
2520
July1st to 10thDay
11%7%36%6%46%5%6%9%38%
2440
11th to 20thDay
10%426%6%45%6%6%10%41%
2340
21st to endDay
10%6%26%7%46%6%7%10%37%
2547
August1st to 10thDay
9%5%26%6%46%6%7%9%38%
2327
11th to 20thDay
10%5%36%6%46%8%7%10%35%
2303
21st to endDay
9%5%36%6%46%6%7%10%40%
2566
September1st to 10thDay
14%5%36%5%445%5%7%43%
1990
11th to 20thDay
10%6%36%6%346%6%8%41%
1980
21st to endDay
18%7%35%5%34346%42%
1980
October1st to 10thDay
15%8%26%5%345%6%8%40%
1904
11th to 20thDay
16%10%36%5%345%5%7%37%
1800
21st to endDay
20%12%36%6%3345%6%30%
1940
November1st to 10thDay
11%8%46%5%35%46%7%43%
1672
11th to 20thDay
17%13%5%7%6%34436%32%
1710
21st to endDay
18%14%6%8%5%34445%27%
1690
December1st to 10thDay
18%16%9%12%7%34445%19%
1520
11th to 20thDay
17%16%7%11%7%34447%20%
2042
21st to endDay
23%24%9%9%6%3334412%
3124
January1st to 10thNight
17%16%7%10%7%35%45%421%
2459
11th to 20thNight
17%17%7%11%9%4434419%
2470
21st to endNight
16%17%7%10%9%3444420%
2711
February1st to 10thNight
20%14%6%10%8%3445%5%22%
2340
11th to 20thNight
16%13%6%9%8%35%45%6%24%
2156
21st to endNight
19%14%6%10%6%44445%24%
1776
March1st to 10thNight
16%11%5%8%7%35%445%32%
2065
11th to 20thNight
15%9%47%5%35%45%8%35%
1980
21st to endNight
19%10%47%6%34445%33%
2178
April1st to 10thNight
15%10%46%5%35%45%8%34%
1976
11th to 20thNight
15%7%36%6%45%45%8%36%
1609
21st to endNight
15%10%35%6%45%45%8%35%
1620
May1st to 10thNight
17%9%36%7%45%5%6%7%31%
1620
11th to 20thNight
18%8%37%43435%7%38%
1592
21st to endNight
8%5%26%5%35%7%7%12%41%
1744
June1st to 10thNight
8%6%35%7%445%5%8%45%
1620
11th to 20thNight
8%5%35%5%35%6%8%10%42%
1604
21st to endNight
10%426%5%35%6%6%9%45%
1440
July1st to 10thNight
8%6%35%5%35%46%9%46%
1512
11th to 20thNight
6%4245%36%6%7%10%47%
1620
21st to endNight
7%5%35%5%35%7%6%10%43%
1771
August1st to 10thNight
6%425%5%35%7%7%11%44%
1611
11th to 20thNight
8%6%35%5%346%7%9%45%
1598
21st to endNight
7%424425%5%7%9%51%
1782
September1st to 10thNight
12%5%244345%5%6%50%
1955
11th to 20thNight
10%415%3245%5%7%55%
1980
21st to endNight
14%7%25%5%3346%7%45%
1980
October1st to 10thNight
11%6%245%345%5%7%47%
2056
11th to 20thNight
16%9%36%6%2445%7%39%
2160
21st to endNight
22%9%36%5%34446%34%
2415
November1st to 10thNight
13%8%35%5%2445%7%43%
2406
11th to 20thNight
16%12%47%6%3445%7%34%
2470
21st to endNight
19%12%5%8%5%3445%6%28%
2482
December1st to 10thNight
20%15%7%10%6%345%45%21%
2660
11th to 20thNight
17%14%7%10%6%35%45%6%24%
3138
21st to endNight
22%19%10%9%6%3434414%
4532

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 10thDay
69%38%15%5%
1707
11th to 20thDay
73%311%10%3
1710
21st to endDay
74%37%11%41
1872
February1st to 10thDay
69%28%14%5%1
1620
11th to 20thDay
65%47%15%7%1
1696
21st to endDay
60%111%18%7%2
1480
March1st to 10thDay
59%210%21%7%
1894
11th to 20thDay
58%39%19%10%2
1980
21st to endDay
61%28%21%8%1
2178
April1st to 10thDay
54%312%18%12%1
1999
11th to 20thDay
52%311%17%14%2
2298
21st to endDay
54%39%21%12%2
2340
May1st to 10thDay
54%312%19%10%1
2340
11th to 20thDay
53%5%12%17%12%1
2305
21st to endDay
43%7%12%24%13%1
2531
June1st to 10thDay
44%411%26%14%1
2340
11th to 20thDay
46%413%22%13%1
2345
21st to endDay
42%414%23%15%2
2520
July1st to 10thDay
43%6%11%23%15%2
2375
11th to 20thDay
38%5%12%27%15%2
2271
21st to endDay
40%6%13%25%13%3
2405
August1st to 10thDay
40%6%13%26%14%1
2314
11th to 20thDay
43%5%14%25%11%2
2303
21st to endDay
39%5%12%23%16%5%
2566
September1st to 10thDay
41%5%12%22%17%4
1990
11th to 20thDay
39%312%26%17%3
1980
21st to endDay
44%39%23%20%1
1980
October1st to 10thDay
43%410%25%17%1
1904
11th to 20thDay
47%310%23%15%1
1800
21st to endDay
56%212%19%10%1
1940
November1st to 10thDay
41%212%26%17%2
1672
11th to 20thDay
56%38%21%10%2
1710
21st to endDay
60%39%18%8%1
1690
December1st to 10thDay
70%29%15%4
1520
11th to 20thDay
67%37%18%5%
2039
21st to endDay
79%19%7%3
3124
January1st to 10thNight
67%37%17%7%
2459
11th to 20thNight
70%210%13%4
2470
21st to endNight
68%38%15%6%1
2711
February1st to 10thNight
66%39%15%6%1
2340
11th to 20thNight
62%49%17%8%1
2158
21st to endNight
64%38%15%9%2
1776
March1st to 10thNight
55%310%21%11%1
2065
11th to 20thNight
48%411%24%11%3
1980
21st to endNight
55%37%21%12%2
2178
April1st to 10thNight
49%411%20%15%2
1976
11th to 20thNight
47%311%18%18%3
1609
21st to endNight
47%410%22%15%2
1620
May1st to 10thNight
53%410%19%12%2
1620
11th to 20thNight
47%411%20%16%3
1593
21st to endNight
35%6%17%25%15%2
1745
June1st to 10thNight
38%5%12%25%18%2
1620
11th to 20thNight
36%5%16%25%17%2
1604
21st to endNight
35%5%14%26%17%3
1440
July1st to 10thNight
36%5%11%24%19%5%
1468
11th to 20thNight
31%6%14%29%18%2
1566
21st to endNight
35%5%14%28%15%4
1672
August1st to 10thNight
33%6%15%29%17%1
1600
11th to 20thNight
36%5%15%28%16%1
1598
21st to endNight
29%6%15%26%20%4
1782
September1st to 10thNight
35%412%26%17%6%
1955
11th to 20thNight
30%411%29%25%2
1980
21st to endNight
39%410%23%22%2
1980
October1st to 10thNight
37%411%25%21%2
2056
11th to 20thNight
47%38%26%15%1
2160
21st to endNight
53%38%23%11%2
2415
November1st to 10thNight
42%311%24%17%3
2406
11th to 20thNight
53%38%22%13%2
2470
21st to endNight
58%212%20%7%1
2482
December1st to 10thNight
67%39%15%6%1
2660
11th to 20thNight
62%310%20%5%
3140
21st to endNight
75%29%11%3
4532

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 10thDay
30%27%29%9%4
270
11th to 20thDay
30%27%33%7%2
270
21st to endDay
31%29%29%9%1
294
February1st to 10thDay
40%23%26%11%
240
11th to 20thDay
32%32%28%7%
240
21st to endDay
29%37%28%5%1
198
March1st to 10thDay
29%26%31%13%2
334
11th to 20thDay
29%20%33%13%5%1
420
21st to endDay
34%18%27%17%4
462
April1st to 10thDay
25%19%32%15%7%2
420
11th to 20thDay
25%23%25%16%7%4
412
21st to endDay
30%16%32%15%5%3
420
May1st to 10thDay
26%16%32%16%7%4
423
11th to 20thDay
25%11%31%18%11%4
447
21st to endDay
13%11%26%28%15%8%
485
June1st to 10thDay
15%7%33%29%11%5%
450
11th to 20thDay
18%10%26%27%16%3
455
21st to endDay
14%10%32%27%14%4
630
July1st to 10thDay
15%419%28%21%13%
545
11th to 20thDay
13%426%28%20%10%
444
21st to endDay
10%423%33%21%9%
488
August1st to 10thDay
12%5%20%30%21%13%
446
11th to 20thDay
14%426%27%19%10%
439
21st to endDay
10%6%22%31%21%11%
495
September1st to 10thDay
14%6%23%24%22%10%
450
11th to 20thDay
11%417%30%26%12%
450
21st to endDay
23%10%21%25%15%7%
450
October1st to 10thDay
13%12%29%23%18%5%
450
11th to 20thDay
22%18%28%22%9%2
450
21st to endDay
29%18%30%18%5%
455
November1st to 10thDay
17%23%35%14%10%1
270
11th to 20thDay
29%20%30%16%6%1
270
21st to endDay
29%24%35%11%1
260
December1st to 10thDay
24%32%29%9%42
180
11th to 20thDay
25%28%35%9%4
220
21st to endDay
35%22%31%11%1
297
January1st to 10thNight
27%23%32%15%2
760
11th to 20thNight
28%24%31%14%3
760
21st to endNight
25%23%31%18%3
835
February1st to 10thNight
28%19%35%16%2
720
11th to 20thNight
26%22%32%17%2
703
21st to endNight
29%20%35%15%2
592
March1st to 10thNight
24%19%32%21%4
720
11th to 20thNight
22%18%33%20%6%1
720
21st to endNight
27%13%32%21%7%1
792
April1st to 10thNight
22%16%34%23%5%
716
11th to 20thNight
21%12%36%20%9%2
533
21st to endNight
20%10%39%24%6%1
540
May1st to 10thNight
22%9%32%27%9%1
540
11th to 20thNight
23%6%29%27%14%1
531
21st to endNight
11%425%34%24%3
584
June1st to 10thNight
12%328%39%17%1
540
11th to 20thNight
13%425%39%18%2
540
21st to endNight
11%426%37%19%2
540
July1st to 10thNight
11%217%40%24%6%
525
11th to 20thNight
7%221%38%27%5%
522
21st to endNight
9%416%42%27%3
591
August1st to 10thNight
9%313%45%26%5%
537
11th to 20thNight
10%216%39%28%4
534
21st to endNight
9%318%35%30%6%
594
September1st to 10thNight
15%5%19%31%27%5%
708
11th to 20thNight
11%315%36%30%5%
720
21st to endNight
18%8%21%30%19%4
720
October1st to 10thNight
15%6%26%31%18%3
720
11th to 20thNight
21%14%30%24%10%1
720
21st to endNight
26%15%30%23%6%
792
November1st to 10thNight
18%14%30%24%12%1
740
11th to 20thNight
25%17%30%21%7%1
760
21st to endNight
26%18%30%20%5%1
760
December1st to 10thNight
31%17%32%17%3
760
11th to 20thNight
26%19%33%19%3
760
21st to endNight
29%18%33%17%3
836
Page generated at 2024-01-28 05:26:37. Version ac07

Copyright 2024 Attilla Danko


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