Allan & Kay Poage Memorial Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Allan & Kay Poage Memorial 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
46%
24087
28%
74456
18%
24029
56%
24029
36%
40947

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
34%
948
31%
2458
11%
946
47%
946
39%
1445
January11th to 20thNight
31%
950
29%
2470
10%
950
44%
950
34%
1483
January21st to endNight
33%
1043
31%
2711
11%
1043
44%
1043
34%
1660
February1st to 10thNight
29%
814
26%
2254
9%
814
41%
814
30%
1380
February11th to 20thNight
24%
704
23%
2098
8%
700
36%
700
27%
1280
February21st to endNight
22%
561
28%
1745
8%
561
37%
561
25%
1044
March1st to 10thNight
29%
540
26%
1980
12%
540
45%
540
24%
1153
March11th to 20thNight
29%
540
24%
1980
13%
540
43%
540
24%
1139
March21st to endNight
28%
594
26%
2178
13%
594
47%
594
27%
1196
April1st to 10thNight
29%
540
28%
1980
13%
540
50%
540
30%
1022
April11th to 20thNight
29%
533
25%
1856
15%
533
45%
533
27%
1033
April21st to endNight
33%
540
29%
1679
15%
540
52%
540
34%
933
May1st to 10thNight
35%
540
27%
1620
17%
540
50%
540
32%
957
May11th to 20thNight
38%
531
21%
1594
16%
531
48%
531
33%
948
May21st to endNight
46%
584
23%
1745
17%
582
58%
582
36%
999
June1st to 10thNight
66%
540
23%
1620
24%
540
72%
540
44%
838
June11th to 20thNight
59%
540
27%
1620
24%
540
68%
540
52%
789
June21st to endNight
68%
540
26%
1620
27%
540
73%
540
47%
828
July1st to 10thNight
70%
525
23%
1575
23%
525
75%
525
43%
840
July11th to 20thNight
80%
522
33%
1566
35%
522
86%
522
65%
689
July21st to endNight
82%
591
31%
1673
34%
558
86%
558
55%
809
August1st to 10thNight
86%
537
37%
1601
41%
534
89%
534
68%
671
August11th to 20thNight
76%
534
34%
1600
36%
534
79%
534
47%
831
August21st to endNight
81%
594
29%
2026
33%
594
83%
594
45%
980
September1st to 10thNight
72%
540
25%
1980
29%
540
74%
540
38%
992
September11th to 20thNight
69%
540
26%
1980
29%
540
72%
540
33%
1058
September21st to endNight
70%
540
36%
1980
35%
540
77%
540
46%
898
October1st to 10thNight
61%
573
36%
2013
30%
573
70%
573
45%
942
October11th to 20thNight
49%
720
35%
2160
18%
720
62%
720
42%
1149
October21st to endNight
44%
792
33%
2376
20%
792
54%
792
38%
1313
November1st to 10thNight
47%
740
32%
2220
18%
740
58%
740
40%
1210
November11th to 20thNight
43%
869
31%
2389
15%
869
54%
869
41%
1339
November21st to endNight
34%
950
30%
2470
12%
950
46%
950
34%
1519
December1st to 10thNight
33%
950
33%
2470
12%
950
47%
950
37%
1478
December11th to 20thNight
32%
949
30%
2857
12%
948
43%
948
28%
1744
December21st to endNight
31%
1039
18%
4312
11%
1026
43%
1026
24%
2358

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
12%5%2443445%7%51%
75091
Night
11%424323347%56%
75062
TransparencyDay
33%5%10%24%22%7%
74816
Night
29%49%23%24%11%
74857
SeeingDay
13%8%24%29%20%6%
14058
Night
13%8%29%34%14%1
24096

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
14%6%23422336%55%
1707
11th to 20thDay
14%6%24323435%54%
1710
21st to endDay
17%7%24313336%52%
1872
February1st to 10thDay
17%7%36%423435%46%
1722
11th to 20thDay
18%8%25%433345%46%
1749
21st to endDay
23%6%23322235%50%
1509
March1st to 10thDay
19%5%245%2345%6%45%
1980
11th to 20thDay
18%6%34434436%46%
1980
21st to endDay
15%6%34444346%48%
2178
April1st to 10thDay
13%5%26%33445%7%47%
1980
11th to 20thDay
14%6%25%5%3445%7%45%
2052
21st to endDay
14%5%2442445%7%48%
2276
May1st to 10thDay
15%43443445%7%46%
2340
11th to 20thDay
13%5%25%6%35%5%5%8%43%
2302
21st to endDay
13%6%35%6%36%6%7%9%37%
2531
June1st to 10thDay
6%3145%35%6%7%8%52%
2340
11th to 20thDay
6%325%5%35%5%6%8%54%
2340
21st to endDay
5%3245%25%46%9%55%
2340
July1st to 10thDay
7%435%6%36%6%8%9%44%
2340
11th to 20thDay
3212335%6%6%8%61%
2340
21st to endDay
33145%35%6%6%11%52%
2546
August1st to 10thDay
21133245%6%10%63%
2328
11th to 20thDay
7%3145%35%5%7%9%51%
2301
21st to endDay
43245%35%6%7%11%51%
2322
September1st to 10thDay
9%42342446%7%55%
1980
11th to 20thDay
11%425%435%5%5%7%48%
1980
21st to endDay
8%31443345%7%57%
1980
October1st to 10thDay
6%323335%35%7%60%
1926
11th to 20thDay
13%413223345%59%
1800
21st to endDay
15%42432323459%
1980
November1st to 10thDay
14%424323336%57%
1858
11th to 20thDay
8%424423446%59%
1786
21st to endDay
16%6%34322345%53%
1710
December1st to 10thDay
15%5%24324446%50%
1710
11th to 20thDay
17%6%25%5%2444446%
2161
21st to endDay
19%7%23323345%49%
3135
January1st to 10thNight
12%5%24323346%58%
2458
11th to 20thNight
16%5%23322345%56%
2470
21st to endNight
15%5%3332334455%
2711
February1st to 10thNight
16%5%24323335%53%
2254
11th to 20thNight
17%7%24424245%50%
2098
21st to endNight
20%5%24322345%51%
1745
March1st to 10thNight
17%5%25%42336%7%46%
1980
11th to 20thNight
15%6%24325%447%49%
1980
21st to endNight
12%5%245%24446%54%
2178
April1st to 10thNight
10%42342345%9%54%
1980
11th to 20thNight
14%5%24414446%51%
1856
21st to endNight
12%5%2332335%7%55%
1679
May1st to 10thNight
10%5%25%325%5%5%8%50%
1620
11th to 20thNight
11%4245%35%45%9%49%
1593
21st to endNight
10%424435%37%10%49%
1745
June1st to 10thNight
5%21343447%10%58%
1620
11th to 20thNight
421333335%10%62%
1620
21st to endNight
421342446%10%59%
1620
July1st to 10thNight
43244345%6%11%54%
1620
11th to 20thNight
3112222348%72%
1620
21st to endNight
12133345%7%12%60%
1772
August1st to 10thNight
211112236%9%72%
1611
11th to 20thNight
5%41342445%9%59%
1600
21st to endNight
43133345%7%10%57%
2026
September1st to 10thNight
8%32432436%7%57%
1980
11th to 20thNight
12%5%1333445%7%53%
1980
21st to endNight
6%312323447%64%
1980
October1st to 10thNight
7%21332435%6%63%
2013
11th to 20thNight
12%423213235%63%
2160
21st to endNight
16%5%2321223361%
2376
November1st to 10thNight
10%5%25%32333461%
2220
11th to 20thNight
7%42432345%6%59%
2389
21st to endNight
16%5%24322345%53%
2470
December1st to 10thNight
13%5%24323336%55%
2470
11th to 20thNight
13%6%35%433345%51%
3036
21st to endNight
17%5%24323235%53%
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
32%38%20%30%7%
1708
11th to 20thDay
34%37%24%27%6%
1710
21st to endDay
36%35%18%28%10%
1872
February1st to 10thDay
43%35%19%20%10%
1722
11th to 20thDay
44%27%19%20%8%
1759
21st to endDay
40%3417%22%14%
1509
March1st to 10thDay
41%36%17%21%12%
1980
11th to 20thDay
41%48%18%23%6%
1980
21st to endDay
38%49%20%21%8%
2178
April1st to 10thDay
37%410%21%18%10%
1980
11th to 20thDay
38%5%9%18%21%8%
2052
21st to endDay
36%5%9%21%24%5%
2276
May1st to 10thDay
38%5%8%23%19%7%
2340
11th to 20thDay
40%6%12%22%18%2
2306
21st to endDay
41%8%12%22%14%2
2531
June1st to 10thDay
27%8%16%29%17%3
2340
11th to 20thDay
28%5%12%31%18%5%
2340
21st to endDay
26%6%12%29%24%4
2340
July1st to 10thDay
33%7%17%28%14%1
2276
11th to 20thDay
19%7%13%36%21%4
2271
21st to endDay
23%7%18%38%14%1
2405
August1st to 10thDay
16%6%15%35%25%3
2314
11th to 20thDay
28%7%14%29%19%3
2301
21st to endDay
25%8%14%31%18%4
2322
September1st to 10thDay
27%5%10%25%23%10%
1980
11th to 20thDay
36%6%10%20%22%7%
1980
21st to endDay
26%47%24%27%12%
1980
October1st to 10thDay
24%410%24%21%16%
1926
11th to 20thDay
28%36%18%28%17%
1800
21st to endDay
32%36%17%26%16%
1980
November1st to 10thDay
31%39%23%25%9%
1858
11th to 20thDay
27%39%20%30%11%
1786
21st to endDay
36%35%21%25%10%
1710
December1st to 10thDay
36%38%22%24%7%
1710
11th to 20thDay
41%36%15%26%8%
2159
21st to endDay
38%35%23%22%8%
3135
January1st to 10thNight
30%27%20%28%12%
2458
11th to 20thNight
32%37%21%27%10%
2470
21st to endNight
35%2417%28%14%
2711
February1st to 10thNight
36%47%17%22%13%
2254
11th to 20thNight
39%36%17%25%10%
2098
21st to endNight
38%37%15%20%17%
1745
March1st to 10thNight
38%47%17%20%14%
1980
11th to 20thNight
36%5%9%14%26%9%
1980
21st to endNight
33%410%21%24%8%
2178
April1st to 10thNight
28%5%11%23%20%13%
1980
11th to 20thNight
35%38%21%18%15%
1856
21st to endNight
31%49%23%28%5%
1679
May1st to 10thNight
33%6%9%23%21%9%
1620
11th to 20thNight
33%6%15%25%19%3
1594
21st to endNight
30%6%18%27%18%3
1746
June1st to 10thNight
21%7%16%32%20%5%
1620
11th to 20thNight
19%413%36%21%8%
1620
21st to endNight
20%7%13%28%27%6%
1620
July1st to 10thNight
24%7%17%34%16%3
1575
11th to 20thNight
12%414%37%27%6%
1566
21st to endNight
15%7%19%38%20%2
1673
August1st to 10thNight
10%314%38%31%5%
1601
11th to 20thNight
22%5%14%30%23%6%
1600
21st to endNight
21%6%14%33%23%4
2026
September1st to 10thNight
26%5%11%23%24%10%
1980
11th to 20thNight
30%5%12%21%22%11%
1980
21st to endNight
21%38%23%28%16%
1980
October1st to 10thNight
21%49%26%20%19%
2013
11th to 20thNight
27%36%16%26%22%
2160
21st to endNight
30%3417%26%20%
2376
November1st to 10thNight
28%36%21%27%14%
2220
11th to 20thNight
27%37%20%28%15%
2389
21st to endNight
35%37%17%28%11%
2470
December1st to 10thNight
32%38%22%24%11%
2470
11th to 20thNight
37%36%16%27%12%
3037
21st to endNight
35%36%18%26%12%
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
20%12%41%23%4
270
11th to 20thDay
21%20%37%16%5%1
270
21st to endDay
22%16%39%18%5%
294
February1st to 10thDay
23%18%36%20%2
240
11th to 20thDay
27%20%41%10%3
240
21st to endDay
38%18%34%8%3
198
March1st to 10thDay
29%15%39%15%2
240
11th to 20thDay
32%16%36%14%3
240
21st to endDay
19%21%41%15%4
264
April1st to 10thDay
20%18%39%18%5%
240
11th to 20thDay
21%17%33%22%7%
330
21st to endDay
18%17%36%21%6%1
536
May1st to 10thDay
15%12%39%27%5%1
603
11th to 20thDay
16%434%31%12%2
625
21st to endDay
14%5%30%33%15%3
679
June1st to 10thDay
6%317%41%25%8%
630
11th to 20thDay
7%320%41%22%7%
630
21st to endDay
5%316%38%27%10%
630
July1st to 10thDay
8%111%35%32%13%
621
11th to 20thDay
27%37%42%11%
618
21st to endDay
315%33%46%13%
684
August1st to 10thDay
318%37%42%10%
626
11th to 20thDay
8%16%37%39%9%
615
21st to endDay
5%17%29%42%16%
441
September1st to 10thDay
7%6%27%43%17%
270
11th to 20thDay
419%30%43%14%
270
21st to endDay
12%310%32%30%14%
270
October1st to 10thDay
3226%36%27%6%
270
11th to 20thDay
14%7%30%30%16%3
270
21st to endDay
27%9%24%23%16%1
297
November1st to 10thDay
21%7%34%26%8%3
270
11th to 20thDay
14%11%33%29%11%2
270
21st to endDay
20%15%36%23%5%
270
December1st to 10thDay
23%10%36%22%7%3
270
11th to 20thDay
23%13%39%19%6%
270
21st to endDay
22%14%40%19%5%
297
January1st to 10thNight
15%10%37%30%8%
950
11th to 20thNight
20%13%31%30%5%
950
21st to endNight
18%13%33%31%6%
1043
February1st to 10thNight
21%13%34%27%5%
814
11th to 20thNight
21%14%38%24%3
704
21st to endNight
23%17%37%21%3
561
March1st to 10thNight
20%11%36%27%6%
540
11th to 20thNight
20%11%38%28%4
540
21st to endNight
14%14%42%25%5%
594
April1st to 10thNight
11%15%42%28%41
540
11th to 20thNight
18%13%38%26%6%
533
21st to endNight
15%10%40%26%8%1
540
May1st to 10thNight
11%8%41%33%6%1
540
11th to 20thNight
12%440%30%13%1
531
21st to endNight
10%5%33%37%14%1
584
June1st to 10thNight
6%219%47%23%3
540
11th to 20thNight
5%130%47%16%
540
21st to endNight
4121%45%26%3
540
July1st to 10thNight
4117%42%31%5%
525
11th to 20thNight
313%49%33%2
522
21st to endNight
119%51%34%4
591
August1st to 10thNight
218%53%32%4
537
11th to 20thNight
7%19%46%31%6%
534
21st to endNight
416%42%41%6%
594
September1st to 10thNight
9%110%40%34%5%
540
11th to 20thNight
13%18%41%35%2
540
21st to endNight
7%117%40%30%4
540
October1st to 10thNight
7%224%37%27%3
573
11th to 20thNight
14%6%27%36%15%1
720
21st to endNight
20%7%27%31%14%1
792
November1st to 10thNight
12%433%36%14%1
740
11th to 20thNight
10%10%34%33%12%1
869
21st to endNight
19%11%33%27%10%1
950
December1st to 10thNight
17%9%37%30%7%
950
11th to 20thNight
20%9%33%31%6%
950
21st to endNight
19%10%35%30%6%
1045
Page generated at 2024-01-28 04:26:32. Version ac07

Copyright 2024 Attilla Danko


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