Sheldon Lake State Park & Environmental Learning Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sheldon Lake State Park & Environmental Learning Center clear sky chart from 2005-11-06 to 2024-01-13.

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
54%
23676
23%
74250
19%
23619
59%
23619
31%
44062

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
36%
949
25%
2458
11%
946
44%
946
31%
1608
January11th to 20thNight
40%
915
24%
2379
11%
915
46%
915
31%
1559
January21st to endNight
37%
990
25%
2574
11%
990
44%
990
29%
1717
February1st to 10thNight
32%
848
21%
2288
9%
848
38%
848
25%
1560
February11th to 20thNight
34%
666
20%
2060
11%
662
40%
662
23%
1334
February21st to endNight
27%
444
23%
1628
12%
444
39%
444
17%
1059
March1st to 10thNight
37%
540
23%
1980
15%
540
46%
540
22%
1237
March11th to 20thNight
41%
540
20%
1980
16%
540
48%
540
22%
1221
March21st to endNight
41%
594
24%
2178
18%
594
51%
594
27%
1244
April1st to 10thNight
38%
540
21%
1980
16%
540
47%
540
21%
1230
April11th to 20thNight
38%
533
23%
1799
17%
533
49%
533
25%
1094
April21st to endNight
44%
540
25%
1800
20%
540
53%
540
26%
1097
May1st to 10thNight
47%
540
21%
1784
20%
540
52%
540
26%
1093
May11th to 20thNight
57%
531
23%
1594
24%
531
60%
531
33%
950
May21st to endNight
65%
583
21%
1746
22%
582
68%
582
34%
1029
June1st to 10thNight
79%
540
23%
1620
26%
540
80%
540
47%
831
June11th to 20thNight
80%
540
22%
1620
24%
540
83%
540
46%
834
June21st to endNight
71%
540
17%
1620
21%
540
72%
540
34%
957
July1st to 10thNight
78%
525
15%
1575
19%
525
78%
525
33%
946
July11th to 20thNight
85%
522
21%
1566
25%
522
85%
522
44%
824
July21st to endNight
84%
591
18%
1673
22%
558
85%
558
41%
928
August1st to 10thNight
89%
537
25%
1601
27%
534
90%
534
59%
733
August11th to 20thNight
84%
534
23%
1706
26%
534
85%
534
44%
878
August21st to endNight
79%
594
18%
1984
21%
594
79%
594
33%
1137
September1st to 10thNight
78%
540
18%
1980
21%
540
79%
540
31%
1079
September11th to 20thNight
69%
540
21%
1980
25%
540
70%
540
27%
1171
September21st to endNight
72%
540
28%
1980
31%
540
73%
540
33%
1040
October1st to 10thNight
76%
643
31%
2083
29%
643
78%
643
44%
1053
October11th to 20thNight
66%
720
33%
2160
25%
720
71%
720
42%
1164
October21st to endNight
57%
792
34%
2376
26%
792
62%
792
39%
1314
November1st to 10thNight
64%
740
28%
2220
23%
740
67%
740
39%
1240
November11th to 20thNight
53%
760
30%
2280
22%
760
59%
760
34%
1332
November21st to endNight
45%
788
28%
2308
18%
788
53%
788
29%
1457
December1st to 10thNight
44%
950
26%
2470
15%
950
50%
950
29%
1649
December11th to 20thNight
38%
949
23%
2880
11%
948
43%
948
23%
1899
December21st to endNight
36%
1038
14%
4340
11%
1026
42%
1026
18%
2564

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%6%36%6%45%6%6%8%40%
74964
Night
13%5%2443445%8%48%
74804
TransparencyDay
41%5%12%20%16%7%
74689
Night
36%413%21%17%8%
74599
SeeingDay
14%417%27%25%14%
13713
Night
16%318%34%25%3
23686

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
19%7%35%43445%6%42%
1707
11th to 20thDay
18%7%34424446%44%
1643
21st to endDay
18%6%36%6%2345%6%41%
1782
February1st to 10thDay
23%9%45%5%3335%6%34%
1687
11th to 20thDay
22%9%45%5%24346%36%
1785
21st to endDay
21%9%36%5%2445%5%38%
1628
March1st to 10thDay
22%8%26%6%3445%5%34%
1980
11th to 20thDay
18%8%35%6%35%45%6%38%
1980
21st to endDay
16%6%36%5%3445%6%41%
2178
April1st to 10thDay
16%7%28%5%45%5%5%6%37%
1980
11th to 20thDay
18%7%35%5%3445%7%39%
2107
21st to endDay
10%6%36%5%35%5%5%7%43%
2160
May1st to 10thDay
10%6%38%6%45%5%6%7%40%
2170
11th to 20thDay
10%6%37%6%45%5%7%8%41%
2302
21st to endDay
10%6%36%7%5%7%7%8%10%30%
2531
June1st to 10thDay
6%425%7%47%7%8%9%40%
2340
11th to 20thDay
5%325%7%5%8%9%8%10%39%
2340
21st to endDay
7%6%37%8%5%9%8%8%9%29%
2340
July1st to 10thDay
10%5%27%7%5%7%8%9%12%29%
2340
11th to 20thDay
6%426%7%5%8%8%8%11%34%
2340
21st to endDay
5%436%8%5%7%9%9%12%34%
2546
August1st to 10thDay
32247%48%7%10%12%41%
2328
11th to 20thDay
4425%8%47%8%8%11%39%
2194
21st to endDay
8%5%35%7%5%7%7%8%10%34%
2367
September1st to 10thDay
6%5%36%8%5%8%7%7%9%37%
1980
11th to 20thDay
15%5%37%6%47%6%6%6%35%
1980
21st to endDay
9%6%25%5%45%5%6%7%46%
1980
October1st to 10thDay
7%424435%45%7%55%
1857
11th to 20thDay
11%425%5%346%5%7%49%
1800
21st to endDay
14%5%24323436%54%
1980
November1st to 10thDay
10%5%25%5%36%5%5%6%48%
1858
11th to 20thDay
11%7%26%5%345%5%6%46%
1900
21st to endDay
17%6%27%6%33447%41%
1868
December1st to 10thDay
16%8%45%5%3435%7%39%
1710
11th to 20thDay
15%6%35%5%35%5%5%7%41%
2161
21st to endDay
17%7%25%434446%44%
3135
January1st to 10thNight
19%8%24323346%46%
2458
11th to 20thNight
20%6%25%323335%47%
2379
21st to endNight
19%7%35%424446%43%
2574
February1st to 10thNight
20%9%26%43335%6%39%
2288
11th to 20thNight
22%8%35%423335%43%
2060
21st to endNight
24%8%25%433445%38%
1628
March1st to 10thNight
21%8%2442435%7%40%
1980
11th to 20thNight
17%7%35%42445%8%40%
1980
21st to endNight
15%6%34433347%48%
2178
April1st to 10thNight
14%6%36%5%35%5%6%7%39%
1980
11th to 20thNight
19%6%24424347%44%
1799
21st to endNight
15%5%26%5%36%447%45%
1800
May1st to 10thNight
14%7%25%43446%9%42%
1784
11th to 20thNight
10%5%245%345%6%8%47%
1593
21st to endNight
8%4245%46%6%7%10%46%
1745
June1st to 10thNight
5%32342345%11%58%
1620
11th to 20thNight
422333447%12%56%
1620
21st to endNight
6%325%445%6%9%11%44%
1620
July1st to 10thNight
6%425%5%45%6%7%11%45%
1620
11th to 20thNight
232342446%12%58%
1620
21st to endNight
33135%346%7%11%53%
1772
August1st to 10thNight
211232335%12%66%
1611
11th to 20thNight
43225%245%7%13%53%
1706
21st to endNight
5%315%5%45%6%7%13%46%
1984
September1st to 10thNight
5%435%4246%7%11%48%
1980
11th to 20thNight
11%7%344345%5%8%45%
1980
21st to endNight
9%425%4345%5%8%53%
1980
October1st to 10thNight
5%31442445%8%59%
2083
11th to 20thNight
10%31432345%6%58%
2160
21st to endNight
11%5%24323335%59%
2376
November1st to 10thNight
10%424423446%55%
2220
11th to 20thNight
12%5%2343445%6%51%
2280
21st to endNight
17%6%25%434446%45%
2308
December1st to 10thNight
18%7%25%5%34346%43%
2470
11th to 20thNight
17%8%26%5%24445%43%
3036
21st to endNight
17%7%35%5%2445%6%45%
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
45%35%17%21%9%
1708
11th to 20thDay
43%35%17%21%12%
1643
21st to endDay
45%35%16%18%12%
1782
February1st to 10thDay
53%25%14%15%11%
1687
11th to 20thDay
52%27%14%18%8%
1795
21st to endDay
50%38%15%14%10%
1628
March1st to 10thDay
51%310%14%17%6%
1980
11th to 20thDay
46%48%13%19%9%
1980
21st to endDay
42%410%16%22%6%
2178
April1st to 10thDay
47%49%18%15%8%
1980
11th to 20thDay
46%39%17%16%9%
2107
21st to endDay
39%311%20%21%6%
2160
May1st to 10thDay
42%5%11%17%18%7%
2170
11th to 20thDay
40%311%25%17%4
2306
21st to endDay
44%6%14%23%12%1
2531
June1st to 10thDay
35%6%15%26%16%1
2340
11th to 20thDay
35%6%16%27%14%2
2340
21st to endDay
47%7%17%21%8%
2340
July1st to 10thDay
42%7%23%22%5%
2276
11th to 20thDay
39%8%24%22%8%
2271
21st to endDay
37%7%24%27%41
2405
August1st to 10thDay
30%7%23%30%10%1
2314
11th to 20thDay
37%9%20%26%7%1
2194
21st to endDay
42%8%20%21%7%2
2367
September1st to 10thDay
39%9%16%18%14%4
1980
11th to 20thDay
47%7%12%16%15%3
1980
21st to endDay
35%313%22%17%9%
1980
October1st to 10thDay
28%49%26%19%14%
1857
11th to 20thDay
33%6%6%20%21%14%
1800
21st to endDay
34%26%16%25%17%
1980
November1st to 10thDay
36%49%20%22%10%
1858
11th to 20thDay
38%310%15%22%12%
1900
21st to endDay
45%36%17%18%11%
1868
December1st to 10thDay
46%29%19%17%7%
1710
11th to 20thDay
44%38%14%21%9%
2159
21st to endDay
42%27%16%21%11%
3135
January1st to 10thNight
42%26%17%21%12%
2458
11th to 20thNight
41%26%17%21%12%
2379
21st to endNight
44%25%17%19%13%
2574
February1st to 10thNight
48%27%13%17%13%
2288
11th to 20thNight
46%27%14%18%12%
2060
21st to endNight
49%36%14%15%13%
1628
March1st to 10thNight
44%49%17%17%9%
1980
11th to 20thNight
44%312%13%20%8%
1980
21st to endNight
39%312%17%21%9%
2178
April1st to 10thNight
44%410%18%15%9%
1980
11th to 20thNight
42%310%17%15%13%
1799
21st to endNight
41%38%21%19%7%
1800
May1st to 10thNight
39%6%11%20%16%8%
1784
11th to 20thNight
36%412%24%20%4
1594
21st to endNight
32%6%20%28%12%1
1746
June1st to 10thNight
22%5%22%33%18%
1620
11th to 20thNight
23%419%32%18%3
1620
21st to endNight
32%6%23%28%10%1
1620
July1st to 10thNight
33%7%27%27%5%
1575
11th to 20thNight
21%8%33%31%7%
1566
21st to endNight
23%10%31%32%5%
1673
August1st to 10thNight
14%5%32%39%10%
1601
11th to 20thNight
21%8%32%32%7%1
1706
21st to endNight
29%9%25%28%7%2
1984
September1st to 10thNight
30%7%24%22%13%4
1980
11th to 20thNight
37%6%15%22%16%4
1980
21st to endNight
31%414%23%19%9%
1980
October1st to 10thNight
24%411%29%19%13%
2083
11th to 20thNight
26%48%24%23%13%
2160
21st to endNight
30%36%17%23%20%
2376
November1st to 10thNight
30%311%23%21%10%
2220
11th to 20thNight
34%39%21%21%12%
2280
21st to endNight
41%28%20%18%9%
2308
December1st to 10thNight
44%29%21%15%10%
2470
11th to 20thNight
44%38%12%19%14%
3037
21st to endNight
43%37%14%26%8%
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
27%6%34%23%9%1
270
11th to 20thDay
23%8%27%31%8%2
248
21st to endDay
22%10%31%28%8%
264
February1st to 10thDay
28%7%32%25%8%
240
11th to 20thDay
28%13%30%20%9%1
240
21st to endDay
27%9%44%18%21
198
March1st to 10thDay
31%9%31%21%8%
240
11th to 20thDay
20%10%41%20%8%2
240
21st to endDay
21%11%33%24%10%1
264
April1st to 10thDay
18%11%37%24%10%
240
11th to 20thDay
26%9%26%21%16%2
385
21st to endDay
15%6%30%31%16%2
420
May1st to 10thDay
16%5%28%31%18%1
433
11th to 20thDay
12%325%34%21%4
625
21st to endDay
12%221%38%22%5%
679
June1st to 10thDay
8%19%35%32%15%
630
11th to 20thDay
7%19%37%31%15%
630
21st to endDay
10%8%28%33%22%
630
July1st to 10thDay
9%1325%38%24%
621
11th to 20thDay
6%1220%41%31%
618
21st to endDay
41223%39%30%
684
August1st to 10thDay
3222%41%31%
626
11th to 20thDay
6%114%40%40%
508
21st to endDay
10%1314%35%36%
486
September1st to 10thDay
9%121%36%33%
270
11th to 20thDay
14%1324%37%21%
270
21st to endDay
13%227%36%22%
270
October1st to 10thDay
7%7%36%36%13%
270
11th to 20thDay
9%314%37%24%12%
270
21st to endDay
19%6%23%28%18%6%
297
November1st to 10thDay
15%219%33%25%6%
270
11th to 20thDay
17%320%39%17%4
270
21st to endDay
20%11%30%20%17%2
270
December1st to 10thDay
19%330%27%15%6%
270
11th to 20thDay
18%9%31%30%10%1
270
21st to endDay
20%6%35%27%9%2
297
January1st to 10thNight
23%5%30%31%10%
950
11th to 20thNight
24%5%24%37%9%1
915
21st to endNight
22%6%27%36%8%
990
February1st to 10thNight
26%7%27%34%6%
848
11th to 20thNight
27%6%28%31%8%
666
21st to endNight
27%7%33%27%6%
444
March1st to 10thNight
23%5%30%34%8%
540
11th to 20thNight
21%7%26%36%10%
540
21st to endNight
19%430%36%10%1
594
April1st to 10thNight
19%432%36%9%
540
11th to 20thNight
24%426%37%9%1
533
21st to endNight
18%427%37%13%1
540
May1st to 10thNight
17%426%42%11%
540
11th to 20thNight
12%221%44%20%2
531
21st to endNight
8%217%42%28%3
584
June1st to 10thNight
6%15%45%38%5%
540
11th to 20thNight
6%17%42%41%3
540
21st to endNight
7%16%29%49%8%
540
July1st to 10thNight
6%1127%54%11%
525
11th to 20thNight
4124%59%12%
522
21st to endNight
41125%59%10%
591
August1st to 10thNight
2121%65%10%
537
11th to 20thNight
6%118%63%12%
534
21st to endNight
7%1120%57%15%
594
September1st to 10thNight
8%1221%55%13%
540
11th to 20thNight
14%225%50%9%
540
21st to endNight
11%15%26%50%7%
540
October1st to 10thNight
7%19%34%43%6%
643
11th to 20thNight
10%116%40%30%3
720
21st to endNight
14%419%37%24%3
792
November1st to 10thNight
11%215%41%27%2
740
11th to 20thNight
14%422%40%19%
760
21st to endNight
19%5%25%36%14%1
788
December1st to 10thNight
22%423%33%17%1
950
11th to 20thNight
24%424%37%10%1
950
21st to endNight
22%5%27%36%9%
1045
Page generated at 2024-01-10 18:35:24. Version ac07

Copyright 2024 Attilla Danko


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