Shades State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Shades State Park clear sky chart from 2005-11-05 to 2017-09-16.

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
40%
15838
18%
46811
12%
15798
46%
15798
24%
31175

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
21%
899
15%
2506
6%
895
29%
895
17%
1876
January16th to endNight
21%
960
13%
2652
6%
960
27%
960
17%
1995
February1st to 15thNight
23%
706
12%
2117
5%
706
29%
706
16%
1530
February16th to endNight
24%
631
16%
1893
7%
631
32%
631
18%
1354
March1st to 15thNight
25%
720
14%
2160
8%
720
31%
720
18%
1528
March16th to endNight
28%
672
15%
2028
7%
672
37%
672
20%
1413
April1st to 15thNight
32%
539
18%
1797
10%
539
44%
539
22%
1152
April16th to endNight
36%
540
19%
1728
12%
540
46%
540
24%
1123
May1st to 15thNight
35%
540
15%
1620
8%
540
42%
540
21%
1143
May16th to endNight
52%
561
17%
1588
13%
561
56%
561
27%
1053
June1st to 15thNight
60%
540
19%
1440
13%
540
64%
540
38%
873
June16th to endNight
62%
540
19%
1440
15%
540
64%
540
35%
906
July1st to 15thNight
66%
510
16%
1360
13%
510
67%
510
38%
832
July16th to endNight
75%
564
26%
1418
19%
531
79%
531
48%
781
August1st to 15thNight
74%
539
22%
1654
22%
536
75%
536
38%
930
August16th to endNight
70%
573
24%
1910
24%
573
74%
573
36%
1045
September1st to 15thNight
64%
580
26%
1840
25%
580
67%
580
34%
1059
September16th to endNight
61%
661
26%
1826
20%
661
64%
661
35%
1110
October1st to 15thNight
54%
660
30%
1839
23%
660
60%
660
36%
1108
October16th to endNight
32%
704
20%
2252
14%
704
41%
704
24%
1421
November1st to 15thNight
38%
700
26%
2276
18%
700
50%
700
29%
1341
November16th to endNight
30%
720
18%
2340
13%
720
39%
720
19%
1595
December1st to 15thNight
23%
819
10%
2439
5%
819
29%
819
15%
1858
December16th to endNight
17%
960
11%
2688
4%
960
24%
960
12%
2149

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
14%7%36%5%3445%7%36%
47949
Night
14%7%36%5%2445%7%39%
46981
Cloud CoverDay
14%7%35%5%3445%7%37%
47958
Night
14%7%35%5%24446%39%
46986
TransparencyDay
45%5%12%21%12%2
47637
Night
44%5%11%21%14%2
46811
SeeingDay
16%5%24%24%20%8%
5859
Night
17%7%27%30%14%1
15844

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%12%5%9%6%34436%24%
1432
16th to endDay
13%14%6%8%5%35%347%26%
1569
February1st to 15thDay
13%12%5%8%7%45%44427%
1744
16th to endDay
15%12%6%8%6%34337%27%
1580
March1st to 15thDay
20%8%5%7%5%45%346%28%
1790
16th to endDay
16%10%5%7%5%24446%30%
2203
April1st to 15thDay
19%7%25%423447%37%
2151
16th to endDay
18%8%25%5%24447%35%
2232
May1st to 15thDay
21%8%36%5%34447%30%
2331
16th to endDay
12%5%26%7%35%5%6%7%37%
2524
June1st to 15thDay
9%5%245%245%5%8%44%
2520
16th to endDay
9%425%5%35%5%6%9%40%
2520
July1st to 15thDay
10%5%246%35%6%6%9%38%
2520
16th to endDay
5%4245%37%6%7%11%41%
2652
August1st to 15thDay
7%4245%35%5%6%9%44%
2292
16th to endDay
8%325%5%345%6%9%44%
2292
September1st to 15thDay
11%5%245%35%5%5%6%43%
2107
16th to endDay
12%5%244235%5%7%47%
1824
October1st to 15thDay
14%5%2343445%6%43%
1790
16th to endDay
17%7%25%425%5%45%39%
1620
November1st to 15thDay
13%6%25%423246%47%
1582
16th to endDay
19%8%45%42335%5%36%
1620
December1st to 15thDay
20%12%49%6%23345%26%
1518
16th to endDay
20%15%6%7%6%2435%422%
1536
January1st to 15thNight
18%11%48%6%3433430%
2506
16th to endNight
15%12%6%8%6%34335%29%
2652
February1st to 15thNight
16%11%5%8%5%34346%31%
2115
16th to endNight
15%10%47%5%34345%33%
1893
March1st to 15thNight
18%8%5%6%5%2446%6%33%
2147
16th to endNight
17%7%46%5%24447%35%
2028
April1st to 15thNight
15%6%36%42336%7%39%
1797
16th to endNight
16%5%35%4245%5%6%39%
1728
May1st to 15thNight
17%7%37%5%2436%7%34%
1620
16th to endNight
11%425%6%45%5%5%9%40%
1586
June1st to 15thNight
9%42442335%9%49%
1440
16th to endNight
8%424426%5%7%11%44%
1440
July1st to 15thNight
7%423435%5%7%10%46%
1440
16th to endNight
332342335%10%55%
1514
August1st to 15thNight
6%31442447%9%50%
1665
16th to endNight
6%4145%2346%8%52%
1910
September1st to 15thNight
10%42432346%8%49%
1840
16th to endNight
10%41433435%8%48%
1826
October1st to 15thNight
11%324323446%52%
1839
16th to endNight
18%6%25%424346%43%
2252
November1st to 15thNight
12%5%34423346%48%
2276
16th to endNight
19%9%46%424345%36%
2340
December1st to 15thNight
20%12%5%8%5%25%335%27%
2439
16th to endNight
23%12%5%9%43443423%
2688

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%12%49%6%34345%25%
1432
16th to endDay
13%14%6%8%6%34346%26%
1569
February1st to 15thDay
14%12%5%8%7%45%345%27%
1744
16th to endDay
16%12%6%7%6%34347%28%
1580
March1st to 15thDay
21%8%5%7%5%34446%28%
1800
16th to endDay
16%11%5%7%5%3445%6%30%
2202
April1st to 15thDay
19%7%34423447%37%
2151
16th to endDay
18%8%25%5%24347%35%
2232
May1st to 15thDay
21%8%37%434447%30%
2331
16th to endDay
12%5%35%6%35%5%5%7%37%
2524
June1st to 15thDay
9%5%345%245%5%8%45%
2520
16th to endDay
9%425%6%35%5%6%9%40%
2520
July1st to 15thDay
10%5%25%5%36%6%6%9%39%
2520
16th to endDay
6%3245%36%6%8%10%41%
2652
August1st to 15thDay
8%324445%5%5%9%45%
2292
16th to endDay
8%4145%35%5%6%8%45%
2292
September1st to 15thDay
12%5%245%35%45%7%43%
2107
16th to endDay
13%5%2432445%6%47%
1824
October1st to 15thDay
14%5%2444445%6%43%
1790
16th to endDay
17%8%24425%446%39%
1620
November1st to 15thDay
14%6%23423336%47%
1582
16th to endDay
19%8%45%5%2335%5%36%
1620
December1st to 15thDay
20%13%39%7%23345%26%
1518
16th to endDay
20%15%5%8%5%3435%422%
1536
January1st to 15thNight
18%11%47%6%2443430%
2506
16th to endNight
15%12%6%8%6%34335%29%
2652
February1st to 15thNight
16%11%6%7%5%23345%31%
2108
16th to endNight
15%10%48%6%34435%33%
1893
March1st to 15thNight
19%8%45%5%2345%7%33%
2160
16th to endNight
17%8%36%6%24446%35%
2028
April1st to 15thNight
15%6%35%42445%7%39%
1797
16th to endNight
17%5%26%42445%6%40%
1728
May1st to 15thNight
17%7%36%5%25%35%7%35%
1619
16th to endNight
11%425%6%36%5%5%9%40%
1586
June1st to 15thNight
9%425%42335%9%49%
1440
16th to endNight
8%325%325%5%7%11%44%
1440
July1st to 15thNight
7%3234346%6%10%46%
1440
16th to endNight
332342337%10%55%
1514
August1st to 15thNight
6%3134345%6%9%50%
1665
16th to endNight
6%4245%2445%8%52%
1910
September1st to 15thNight
10%5%2333345%6%50%
1840
16th to endNight
11%42343435%8%49%
1826
October1st to 15thNight
10%415%42345%6%52%
1839
16th to endNight
18%6%24423436%42%
2252
November1st to 15thNight
12%5%24334346%48%
2276
16th to endNight
19%9%45%423345%36%
2340
December1st to 15thNight
20%11%5%8%6%25%33427%
2439
16th to endNight
23%12%5%9%5%2443423%
2688

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
61%49%15%8%
1433
16th to endDay
58%5%13%17%5%
1569
February1st to 15thDay
59%411%15%8%
1746
16th to endDay
57%412%19%5%
1580
March1st to 15thDay
56%413%17%6%
1800
16th to endDay
53%5%13%20%5%
2203
April1st to 15thDay
46%412%22%13%
2151
16th to endDay
47%5%13%18%10%4
2232
May1st to 15thDay
52%6%11%19%9%
2331
16th to endDay
44%7%11%18%15%2
2528
June1st to 15thDay
35%5%13%24%17%2
2520
16th to endDay
38%6%14%20%16%3
2520
July1st to 15thDay
41%6%11%22%16%2
2371
16th to endDay
33%8%17%25%12%1
2485
August1st to 15thDay
33%6%14%25%18%1
2279
16th to endDay
33%7%13%23%15%6%
2292
September1st to 15thDay
39%6%10%22%16%4
2107
16th to endDay
35%5%9%25%20%3
1824
October1st to 15thDay
39%5%11%25%15%2
1790
16th to endDay
45%411%23%13%
1620
November1st to 15thDay
38%311%21%19%5%
1582
16th to endDay
49%410%22%12%
1620
December1st to 15thDay
60%411%16%6%
1518
16th to endDay
64%410%14%4
1536
January1st to 15thNight
56%48%19%9%
2506
16th to endNight
57%312%18%7%
2652
February1st to 15thNight
55%413%17%8%
2117
16th to endNight
53%412%21%8%
1893
March1st to 15thNight
50%5%11%20%10%1
2160
16th to endNight
49%5%13%23%7%1
2028
April1st to 15thNight
44%410%23%15%1
1797
16th to endNight
43%410%20%14%6%
1728
May1st to 15thNight
47%6%12%20%12%
1620
16th to endNight
39%9%12%17%16%4
1588
June1st to 15thNight
32%5%12%28%19%2
1440
16th to endNight
32%7%13%21%18%5%
1440
July1st to 15thNight
29%7%16%22%18%4
1360
16th to endNight
23%5%15%33%20%3
1418
August1st to 15thNight
27%7%14%25%22%2
1654
16th to endNight
28%6%11%26%20%6%
1910
September1st to 15thNight
32%5%10%24%20%6%
1840
16th to endNight
33%5%9%21%24%4
1826
October1st to 15thNight
32%5%9%26%23%3
1839
16th to endNight
42%311%24%15%2
2252
November1st to 15thNight
36%38%24%20%6%
2276
16th to endNight
50%311%21%13%
2340
December1st to 15thNight
60%310%16%8%
2439
16th to endNight
63%49%14%6%
2688

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
31%14%33%14%6%
90
16th to endDay
16%19%39%23%
96
February1st to 15thDay
17%17%44%17%2
90
16th to endDay
19%11%39%20%8%
81
March1st to 15thDay
33%18%33%12%2
90
16th to endDay
25%10%31%21%10%1
274
April1st to 15thDay
23%11%30%21%11%2
270
16th to endDay
25%5%28%21%12%5%
270
May1st to 15thDay
25%10%23%26%10%4
288
16th to endDay
15%429%23%19%8%
424
June1st to 15thDay
13%224%31%20%6%
495
16th to endDay
12%431%27%16%6%
495
July1st to 15thDay
14%122%28%21%12%
475
16th to endDay
7%212%30%30%16%
512
August1st to 15thDay
10%18%21%35%22%
313
16th to endDay
9%113%22%38%14%
332
September1st to 15thDay
14%311%26%30%13%
315
16th to endDay
15%5%11%22%33%12%
257
October1st to 15thDay
11%426%27%23%6%
230
16th to endDay
23%9%38%22%5%
96
November1st to 15thDay
10%8%21%30%21%8%
90
16th to endDay
34%11%31%15%7%
90
December1st to 15thDay
22%8%42%18%6%1
90
16th to endDay
23%19%44%9%2
96
January1st to 15thNight
23%14%34%23%3
900
16th to endNight
20%13%36%26%2
960
February1st to 15thNight
20%12%35%26%3
709
16th to endNight
20%10%38%25%4
631
March1st to 15thNight
22%11%35%25%5%
720
16th to endNight
19%9%35%26%6%1
672
April1st to 15thNight
17%12%34%27%8%
539
16th to endNight
19%5%33%30%10%1
540
May1st to 15thNight
20%6%29%31%11%
540
16th to endNight
13%421%35%22%1
563
June1st to 15thNight
11%218%47%18%
540
16th to endNight
9%120%46%22%
540
July1st to 15thNight
8%116%42%29%1
510
16th to endNight
4210%39%38%5%
564
August1st to 15thNight
7%10%43%33%5%
539
16th to endNight
6%112%31%42%4
573
September1st to 15thNight
12%216%35%28%5%
580
16th to endNight
13%314%31%34%2
661
October1st to 15thNight
13%5%21%34%20%4
660
16th to endNight
23%9%30%26%9%
704
November1st to 15thNight
15%9%34%27%11%1
700
16th to endNight
23%12%28%26%8%
720
December1st to 15thNight
27%9%32%22%6%1
819
16th to endNight
29%10%34%21%4
960
Page generated at 2017-09-17 12:05:47. Version ac04

Copyright 2017 A. Danko


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