STACEE
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the STACEE clear sky chart from 2005-11-06 to 2024-03-18.

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
58%
24356
31%
79939
22%
24260
68%
24260
41%
40272

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
54%
754
29%
4017
25%
736
68%
736
27%
1974
January11th to 20thNight
53%
756
40%
3937
26%
740
65%
740
34%
1543
January21st to endNight
53%
824
22%
4325
25%
814
67%
814
24%
2291
February1st to 10thNight
50%
760
32%
2459
23%
760
64%
760
45%
1190
February11th to 20thNight
45%
743
31%
2218
19%
740
59%
740
40%
1186
February21st to endNight
39%
628
36%
1884
18%
628
58%
628
44%
964
March1st to 10thNight
46%
760
35%
2138
19%
760
59%
760
44%
1122
March11th to 20thNight
48%
752
32%
2068
17%
752
58%
752
43%
1135
March21st to endNight
45%
743
34%
2129
15%
743
61%
743
43%
1126
April1st to 10thNight
41%
540
35%
1800
19%
540
62%
540
44%
812
April11th to 20thNight
42%
533
34%
1777
21%
533
60%
533
40%
859
April21st to endNight
40%
540
35%
1800
19%
540
64%
540
42%
842
May1st to 10thNight
48%
540
31%
1800
22%
540
64%
540
47%
826
May11th to 20thNight
52%
531
26%
1700
20%
531
62%
531
38%
883
May21st to endNight
53%
584
34%
1604
19%
582
67%
582
54%
793
June1st to 10thNight
64%
540
29%
1440
22%
540
69%
540
48%
775
June11th to 20thNight
67%
540
35%
1440
25%
540
74%
540
63%
690
June21st to endNight
66%
540
25%
1440
19%
540
68%
540
44%
824
July1st to 10thNight
69%
525
17%
1526
15%
525
70%
525
33%
921
July11th to 20thNight
77%
522
18%
1566
16%
522
78%
522
36%
903
July21st to endNight
73%
591
16%
1674
16%
558
73%
558
28%
1068
August1st to 10thNight
77%
537
17%
1649
17%
534
77%
534
35%
940
August11th to 20thNight
74%
534
21%
1778
22%
534
76%
534
31%
1015
August21st to endNight
80%
594
26%
1980
28%
594
83%
594
38%
1046
September1st to 10thNight
71%
540
28%
1800
28%
540
75%
540
37%
981
September11th to 20thNight
73%
540
36%
1800
33%
540
79%
540
42%
891
September21st to endNight
70%
616
35%
2014
28%
616
77%
616
51%
925
October1st to 10thNight
62%
720
32%
2160
23%
720
69%
720
45%
1132
October11th to 20thNight
67%
720
41%
2160
25%
720
77%
720
60%
951
October21st to endNight
62%
792
41%
2376
24%
792
73%
792
54%
1110
November1st to 10thNight
67%
740
44%
2220
28%
740
79%
740
65%
946
November11th to 20thNight
64%
920
39%
2440
24%
920
72%
920
62%
1184
November21st to endNight
55%
950
36%
2470
21%
950
63%
950
47%
1358
December1st to 10thNight
57%
950
36%
2622
22%
950
66%
950
51%
1341
December11th to 20thNight
52%
948
31%
3122
20%
948
60%
948
38%
1640
December21st to endNight
50%
1009
21%
4606
21%
998
60%
998
31%
2085

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
34134245%5%7%61%
78871
Night
442443445%7%59%
80970
TransparencyDay
21%5%9%21%28%17%
78597
Night
23%49%20%27%16%
80765
SeeingDay
7%9%24%31%23%6%
14050
Night
6%7%24%40%21%2
24389

By Month

Percentage Cloud Cover SW (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
211%35%32445%6%56%
2858
11th to 20thDay
35%13323447%65%
2860
21st to endDay
49%25%5%445%46%50%
3146
February1st to 10thDay
37%2442335%6%61%
1719
11th to 20thDay
4415%42345%6%61%
1849
21st to endDay
26%14424446%63%
1570
March1st to 10thDay
3425%425%45%7%58%
2038
11th to 20thDay
37%25%323346%61%
2058
21st to endDay
5%4234245%6%8%59%
2226
April1st to 10thDay
231332445%7%66%
2160
11th to 20thDay
4314424345%65%
2131
21st to endDay
331332345%7%67%
2160
May1st to 10thDay
2214323448%68%
2160
11th to 20thDay
332343445%7%61%
2192
21st to endDay
221232445%6%70%
2667
June1st to 10thDay
22124245%6%9%63%
2520
11th to 20thDay
211232335%5%72%
2520
21st to endDay
4413425%5%5%8%60%
2520
July1st to 10thDay
32245%46%7%8%11%47%
2383
11th to 20thDay
3323436%7%10%12%48%
2340
21st to endDay
4325%6%47%7%10%12%40%
2545
August1st to 10thDay
3314447%7%8%10%49%
2280
11th to 20thDay
42135%36%7%8%12%49%
2123
21st to endDay
4213435%7%8%11%51%
2376
September1st to 10thDay
43245%36%6%7%9%52%
2160
11th to 20thDay
5%2133246%5%7%62%
2160
21st to endDay
2312323446%71%
1941
October1st to 10thDay
5%41342346%5%63%
1800
11th to 20thDay
221222233477%
1800
21st to endDay
321232323474%
1980
November1st to 10thDay
2213323347%71%
1859
11th to 20thDay
2214323335%71%
1718
21st to endDay
4423334336%65%
1710
December1st to 10thDay
45%14313347%64%
1554
11th to 20thDay
45%26%4345%6%7%54%
1926
21st to endDay
45%24313347%62%
2862
January1st to 10thNight
211%5%5%434445%54%
4097
11th to 20thNight
5%41432334467%
4110
21st to endNight
5%9%35%435%5%5%8%49%
4521
February1st to 10thNight
36%23323335%65%
2459
11th to 20thNight
6%6%25%32435%6%58%
2218
21st to endNight
5%6%23423345%64%
1884
March1st to 10thNight
5%5%23324447%60%
2138
11th to 20thNight
6%6%24324445%60%
2068
21st to endNight
6%5%2332345%6%60%
2129
April1st to 10thNight
432432335%7%66%
1800
11th to 20thNight
45%24433346%62%
1777
21st to endNight
5%414323346%65%
1800
May1st to 10thNight
332432335%7%65%
1800
11th to 20thNight
5%323435%6%6%8%55%
1700
21st to endNight
4213323345%69%
1604
June1st to 10thNight
2214435%5%8%10%55%
1440
11th to 20thNight
31123235%5%8%68%
1440
21st to endNight
4324446%7%7%8%51%
1440
July1st to 10thNight
3336%7%5%6%8%9%10%42%
1571
11th to 20thNight
3315%6%38%6%10%14%41%
1620
21st to endNight
4336%7%5%8%10%10%13%33%
1773
August1st to 10thNight
3225%5%46%7%9%13%44%
1658
11th to 20thNight
5%3245%47%7%9%11%42%
1778
21st to endNight
3213446%8%9%12%48%
1980
September1st to 10thNight
4326%6%45%6%7%9%49%
1800
11th to 20thNight
5%313435%46%8%58%
1800
21st to endNight
331343335%6%68%
2014
October1st to 10thNight
5%32443435%6%61%
2160
11th to 20thNight
211232233477%
2160
21st to endNight
4313322335%72%
2376
November1st to 10thNight
2212222246%75%
2220
11th to 20thNight
2213323335%74%
2440
21st to endNight
5%6%24423335%63%
2470
December1st to 10thNight
5%41242235%7%64%
2622
11th to 20thNight
44245%3446%9%55%
3271
21st to endNight
5%8%24323345%62%
4832

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
27%38%33%26%4
2859
11th to 20thDay
19%5%11%37%24%4
2860
21st to endDay
33%5%8%22%26%7%
3146
February1st to 10thDay
23%38%25%28%12%
1719
11th to 20thDay
24%37%24%30%13%
1859
21st to endDay
22%3419%32%20%
1570
March1st to 10thDay
24%35%19%32%17%
2038
11th to 20thDay
24%37%18%32%16%
2058
21st to endDay
22%36%19%33%16%
2226
April1st to 10thDay
18%35%17%37%21%
2160
11th to 20thDay
20%35%16%31%24%
2134
21st to endDay
17%36%19%35%20%
2160
May1st to 10thDay
16%35%16%34%26%
2160
11th to 20thDay
21%5%9%18%27%19%
2195
21st to endDay
14%48%15%29%31%
2667
June1st to 10thDay
16%49%19%26%25%
2520
11th to 20thDay
13%35%11%23%45%
2520
21st to endDay
21%49%17%22%26%
2520
July1st to 10thDay
25%8%13%19%18%18%
2319
11th to 20thDay
22%7%19%24%17%10%
2271
21st to endDay
29%11%19%28%12%2
2404
August1st to 10thDay
25%8%20%22%17%9%
2265
11th to 20thDay
23%9%15%25%20%8%
2123
21st to endDay
22%9%13%27%24%6%
2376
September1st to 10thDay
26%7%10%21%24%12%
2160
11th to 20thDay
19%7%10%18%26%21%
2160
21st to endDay
14%46%23%33%20%
1941
October1st to 10thDay
21%5%8%19%26%21%
1800
11th to 20thDay
13%2314%36%31%
1800
21st to endDay
15%36%20%38%17%
1980
November1st to 10thDay
13%35%22%39%18%
1859
11th to 20thDay
15%36%24%39%13%
1718
21st to endDay
22%35%22%35%14%
1710
December1st to 10thDay
21%48%32%25%10%
1554
11th to 20thDay
27%5%10%25%27%7%
1924
21st to endDay
23%39%22%30%14%
2862
January1st to 10thNight
31%39%26%24%7%
4097
11th to 20thNight
21%36%36%27%6%
4110
21st to endNight
33%5%9%21%27%6%
4521
February1st to 10thNight
23%29%22%30%14%
2459
11th to 20thNight
27%36%22%27%15%
2218
21st to endNight
24%3416%33%21%
1884
March1st to 10thNight
24%36%18%32%18%
2138
11th to 20thNight
25%47%16%32%15%
2068
21st to endNight
23%47%16%34%16%
2129
April1st to 10thNight
19%35%17%35%22%
1800
11th to 20thNight
22%46%14%28%27%
1777
21st to endNight
21%37%15%34%20%
1800
May1st to 10thNight
19%37%14%30%26%
1800
11th to 20thNight
24%7%11%16%23%19%
1701
21st to endNight
17%39%13%26%32%
1604
June1st to 10thNight
21%6%12%16%20%25%
1440
11th to 20thNight
14%37%13%19%44%
1440
21st to endNight
26%6%12%13%18%26%
1440
July1st to 10thNight
31%9%16%16%13%15%
1526
11th to 20thNight
27%10%21%20%15%8%
1566
21st to endNight
34%11%23%22%8%2
1674
August1st to 10thNight
27%9%21%22%11%9%
1649
11th to 20thNight
29%10%17%21%14%8%
1778
21st to endNight
22%10%17%26%17%7%
1980
September1st to 10thNight
28%6%15%20%20%12%
1800
11th to 20thNight
24%411%18%21%22%
1800
21st to endNight
19%37%17%31%23%
2014
October1st to 10thNight
24%48%17%24%23%
2160
11th to 20thNight
13%35%12%34%34%
2160
21st to endNight
17%35%18%38%20%
2376
November1st to 10thNight
11%25%21%41%20%
2220
11th to 20thNight
14%35%20%40%18%
2440
21st to endNight
24%35%18%34%17%
2470
December1st to 10thNight
20%38%27%31%10%
2622
11th to 20thNight
25%49%24%29%9%
3272
21st to endNight
26%36%22%31%11%
4832

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
9%6%33%37%14%1
270
11th to 20thDay
14%10%29%30%16%1
270
21st to endDay
6%8%35%32%15%4
297
February1st to 10thDay
8%14%33%30%14%1
270
11th to 20thDay
11%10%41%32%6%
270
21st to endDay
14%15%40%24%7%
225
March1st to 10thDay
10%17%34%30%9%1
408
11th to 20thDay
16%16%31%22%14%1
449
21st to endDay
13%27%32%18%8%1
462
April1st to 10thDay
9%22%35%24%8%2
420
11th to 20thDay
13%20%35%23%8%1
412
21st to endDay
9%22%35%25%8%1
420
May1st to 10thDay
5%17%39%27%9%1
423
11th to 20thDay
5%14%33%31%15%3
448
21st to endDay
411%29%36%18%1
622
June1st to 10thDay
25%20%40%30%4
630
11th to 20thDay
35%20%37%32%3
630
21st to endDay
5%5%18%33%33%5%
630
July1st to 10thDay
3311%35%35%13%
489
11th to 20thDay
317%25%45%20%
444
21st to endDay
32428%41%23%
487
August1st to 10thDay
325%32%43%15%
447
11th to 20thDay
3112%32%37%14%
437
21st to endDay
418%34%40%13%
495
September1st to 10thDay
4313%31%38%11%
450
11th to 20thDay
4218%38%28%9%
450
21st to endDay
47%18%34%26%11%
311
October1st to 10thDay
6%8%24%31%20%11%
270
11th to 20thDay
7%8%22%30%28%5%
270
21st to endDay
10%9%19%34%24%4
297
November1st to 10thDay
6%10%31%31%20%1
270
11th to 20thDay
48%25%40%19%4
270
21st to endDay
11%11%30%28%17%3
270
December1st to 10thDay
7%7%32%35%16%2
270
11th to 20thDay
7%10%34%31%17%1
270
21st to endDay
16%9%32%31%12%1
297
January1st to 10thNight
6%6%29%41%16%3
760
11th to 20thNight
8%7%28%42%15%1
760
21st to endNight
8%8%27%39%16%2
836
February1st to 10thNight
6%9%32%38%14%1
760
11th to 20thNight
10%10%32%39%8%1
744
21st to endNight
9%10%39%37%5%
628
March1st to 10thNight
7%12%33%38%11%1
760
11th to 20thNight
10%10%28%37%14%
752
21st to endNight
8%13%30%39%10%
743
April1st to 10thNight
5%13%36%38%6%1
540
11th to 20thNight
8%14%33%37%9%
533
21st to endNight
8%13%36%35%7%1
540
May1st to 10thNight
5%8%34%44%9%1
540
11th to 20thNight
8%7%27%40%17%1
531
21st to endNight
5%7%30%43%14%1
584
June1st to 10thNight
35%21%52%18%1
540
11th to 20thNight
35%20%50%22%1
540
21st to endNight
6%317%44%28%2
540
July1st to 10thNight
4210%42%38%4
525
11th to 20thNight
418%29%53%5%
522
21st to endNight
5%26%28%52%7%
591
August1st to 10thNight
227%30%50%9%
537
11th to 20thNight
6%19%39%42%4
534
21st to endNight
318%37%47%5%
594
September1st to 10thNight
5%49%42%37%4
540
11th to 20thNight
6%313%42%34%4
540
21st to endNight
4318%43%28%3
616
October1st to 10thNight
5%5%20%47%21%2
720
11th to 20thNight
36%20%49%19%3
720
21st to endNight
6%7%22%38%24%3
792
November1st to 10thNight
35%23%44%23%2
740
11th to 20thNight
35%25%44%20%3
920
21st to endNight
9%9%23%35%21%3
950
December1st to 10thNight
9%6%25%43%17%1
950
11th to 20thNight
9%7%26%42%15%1
950
21st to endNight
10%8%26%46%9%1
1017
Page generated at 2024-03-15 12:01:38. Version ac07

Copyright © 2024 Attilla Danko.


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