Peotone
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peotone clear sky chart from 2005-11-05 to 2017-09-20.

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
38%
15952
18%
46870
11%
15910
45%
15910
25%
30882

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
20%
900
14%
2506
4%
895
28%
895
18%
1821
January16th to endNight
22%
960
14%
2655
6%
960
28%
960
17%
1984
February1st to 15thNight
22%
773
14%
2184
4%
773
30%
773
19%
1552
February16th to endNight
25%
631
18%
1893
7%
631
35%
631
18%
1332
March1st to 15thNight
25%
720
14%
2160
9%
720
30%
720
18%
1522
March16th to endNight
30%
639
16%
2019
9%
639
38%
639
21%
1369
April1st to 15thNight
28%
539
17%
1797
10%
539
40%
539
22%
1166
April16th to endNight
33%
540
19%
1731
11%
540
42%
540
22%
1137
May1st to 15thNight
37%
540
16%
1620
8%
540
44%
540
24%
1087
May16th to endNight
52%
562
18%
1505
10%
561
58%
561
33%
961
June1st to 15thNight
52%
540
18%
1440
11%
540
56%
540
38%
882
June16th to endNight
51%
540
18%
1440
10%
540
56%
540
34%
911
July1st to 15thNight
63%
510
18%
1360
13%
510
66%
510
40%
812
July16th to endNight
71%
564
23%
1417
18%
531
74%
531
44%
824
August1st to 15thNight
78%
539
23%
1593
22%
536
78%
536
44%
854
August16th to endNight
67%
573
22%
1910
22%
573
72%
573
35%
1062
September1st to 15thNight
66%
555
29%
1815
29%
555
70%
555
36%
984
September16th to endNight
61%
677
29%
1870
22%
677
65%
677
37%
1100
October1st to 15thNight
50%
660
29%
1881
21%
660
57%
660
33%
1129
October16th to endNight
28%
704
19%
2244
12%
704
37%
704
21%
1443
November1st to 15thNight
32%
700
25%
2276
16%
700
43%
700
26%
1358
November16th to endNight
26%
726
18%
2346
11%
726
36%
726
19%
1560
December1st to 15thNight
20%
900
13%
2520
4%
900
28%
900
17%
1856
December16th to endNight
16%
960
11%
2688
3%
960
24%
960
12%
2176

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%
47972
Night
14%8%35%5%24446%39%
47039
Cloud CoverDay
14%7%36%5%3445%7%36%
47981
Night
14%7%36%424446%39%
47044
TransparencyDay
46%312%22%12%1
47658
Night
45%311%23%14%2
46871
SeeingDay
15%6%26%26%17%7%
5954
Night
18%8%27%30%13%1
15956

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
16%15%47%6%45%446%24%
1432
16th to endDay
13%16%7%9%5%24436%25%
1566
February1st to 15thDay
15%12%6%7%5%35%447%26%
1678
16th to endDay
15%10%5%8%7%43336%30%
1580
March1st to 15thDay
18%12%47%6%24445%29%
1790
16th to endDay
18%9%46%6%25%5%47%29%
2216
April1st to 15thDay
19%9%45%424247%33%
2151
16th to endDay
19%7%345%44446%35%
2228
May1st to 15thDay
19%8%36%5%3446%7%29%
2331
16th to endDay
12%5%26%5%35%45%7%39%
2606
June1st to 15thDay
11%5%25%5%25%5%48%43%
2520
16th to endDay
10%4246%47%5%7%8%38%
2520
July1st to 15thDay
8%5%25%5%35%5%7%9%42%
2520
16th to endDay
6%325%5%36%6%7%9%42%
2655
August1st to 15thDay
6%425%5%35%6%7%8%44%
2352
16th to endDay
8%5%26%6%35%5%6%7%42%
2292
September1st to 15thDay
12%42433445%7%46%
2133
16th to endDay
9%5%25%5%345%6%8%44%
1859
October1st to 15thDay
13%6%25%43435%6%43%
1746
16th to endDay
18%7%26%5%3345%7%35%
1628
November1st to 15thDay
15%6%24424447%44%
1582
16th to endDay
19%8%46%423346%35%
1611
December1st to 15thDay
18%13%48%6%25%345%26%
1440
16th to endDay
23%13%5%8%5%24435%21%
1536
January1st to 15thNight
18%12%46%6%23445%32%
2506
16th to endNight
14%12%7%8%6%34345%28%
2655
February1st to 15thNight
15%12%47%433435%34%
2182
16th to endNight
16%10%47%5%34446%32%
1893
March1st to 15thNight
17%10%47%5%33345%33%
2147
16th to endNight
15%8%36%6%35%5%5%6%34%
2019
April1st to 15thNight
16%6%46%5%23447%38%
1797
16th to endNight
19%6%35%42445%6%38%
1731
May1st to 15thNight
18%7%25%4245%5%8%36%
1620
16th to endNight
8%5%244345%6%8%43%
1504
June1st to 15thNight
10%425%5%2335%6%50%
1440
16th to endNight
8%6%25%5%3447%9%42%
1440
July1st to 15thNight
6%314425%5%6%8%50%
1440
16th to endNight
432442447%9%51%
1513
August1st to 15thNight
331343446%9%53%
1602
16th to endNight
10%32342445%8%50%
1910
September1st to 15thNight
11%313322446%55%
1815
16th to endNight
8%414435%45%7%49%
1870
October1st to 15thNight
11%5%23424347%50%
1881
16th to endNight
18%8%25%423235%41%
2244
November1st to 15thNight
13%6%35%5%23347%45%
2276
16th to endNight
18%8%35%434346%37%
2346
December1st to 15thNight
21%10%48%5%24335%30%
2520
16th to endNight
23%14%5%7%7%2433421%
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
16%16%46%7%35%446%24%
1432
16th to endDay
13%16%7%8%6%24336%25%
1566
February1st to 15thDay
15%11%6%7%5%35%446%26%
1678
16th to endDay
15%9%5%8%8%34336%31%
1580
March1st to 15thDay
18%12%48%5%24446%28%
1800
16th to endDay
18%9%46%5%25%5%46%30%
2215
April1st to 15thDay
19%9%45%424347%33%
2151
16th to endDay
19%7%245%43446%35%
2228
May1st to 15thDay
20%8%36%5%3446%8%29%
2331
16th to endDay
12%5%26%5%35%45%7%39%
2606
June1st to 15thDay
11%5%25%5%245%5%7%44%
2520
16th to endDay
10%425%6%36%5%7%8%38%
2520
July1st to 15thDay
8%5%15%5%35%5%6%9%42%
2520
16th to endDay
6%325%5%36%6%7%9%42%
2655
August1st to 15thDay
6%425%5%35%5%6%8%44%
2352
16th to endDay
9%436%5%345%6%7%42%
2292
September1st to 15thDay
12%42442446%6%46%
2133
16th to endDay
9%5%25%5%345%5%8%44%
1859
October1st to 15thDay
14%6%25%42435%6%43%
1746
16th to endDay
19%6%26%5%3345%6%35%
1628
November1st to 15thDay
15%6%34423446%44%
1582
16th to endDay
19%8%46%423346%35%
1611
December1st to 15thDay
18%13%48%5%35%345%26%
1440
16th to endDay
23%13%6%7%5%34345%22%
1536
January1st to 15thNight
18%11%47%6%2344432%
2506
16th to endNight
14%11%7%9%5%34345%28%
2655
February1st to 15thNight
15%12%47%424435%34%
2175
16th to endNight
16%10%47%5%2335%6%32%
1893
March1st to 15thNight
18%10%37%433346%33%
2160
16th to endNight
15%8%36%5%35%45%6%34%
2019
April1st to 15thNight
16%7%36%424347%38%
1797
16th to endNight
18%7%3443445%6%38%
1731
May1st to 15thNight
19%6%244245%5%8%36%
1619
16th to endNight
9%5%245%25%5%6%8%44%
1504
June1st to 15thNight
10%43442335%6%50%
1440
16th to endNight
8%6%245%345%6%9%43%
1440
July1st to 15thNight
7%314435%5%5%8%50%
1440
16th to endNight
332442446%9%51%
1513
August1st to 15thNight
331343446%9%53%
1602
16th to endNight
10%22332445%8%50%
1910
September1st to 15thNight
11%313322446%55%
1815
16th to endNight
8%414335%45%8%49%
1870
October1st to 15thNight
11%5%24324337%51%
1881
16th to endNight
19%8%35%423245%41%
2244
November1st to 15thNight
13%6%35%5%23347%45%
2276
16th to endNight
18%8%45%424336%37%
2346
December1st to 15thNight
21%11%48%5%24335%31%
2520
16th to endNight
23%14%6%8%6%3433421%
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
60%212%14%8%
1433
16th to endDay
61%211%16%6%
1566
February1st to 15thDay
58%211%18%7%1
1680
16th to endDay
55%211%23%5%1
1580
March1st to 15thDay
56%312%20%6%
1800
16th to endDay
53%412%22%5%1
2216
April1st to 15thDay
51%39%21%12%
2151
16th to endDay
49%313%17%11%3
2228
May1st to 15thDay
52%311%23%7%
2331
16th to endDay
43%410%21%16%2
2610
June1st to 15thDay
37%411%26%19%1
2520
16th to endDay
39%5%13%23%15%2
2520
July1st to 15thDay
37%5%11%25%16%2
2371
16th to endDay
33%5%18%25%14%2
2488
August1st to 15thDay
33%415%26%17%1
2337
16th to endDay
38%411%23%18%3
2292
September1st to 15thDay
36%49%26%18%4
2133
16th to endDay
36%38%29%19%1
1859
October1st to 15thDay
40%310%28%14%2
1746
16th to endDay
48%312%22%10%1
1628
November1st to 15thDay
40%212%24%17%2
1582
16th to endDay
51%212%24%9%
1611
December1st to 15thDay
60%210%19%7%
1440
16th to endDay
65%310%13%6%
1536
January1st to 15thNight
54%212%18%11%
2506
16th to endNight
58%113%17%8%
2655
February1st to 15thNight
52%211%21%9%1
2184
16th to endNight
52%310%22%10%
1893
March1st to 15thNight
53%211%20%9%1
2160
16th to endNight
48%414%21%9%1
2019
April1st to 15thNight
46%210%23%15%1
1797
16th to endNight
46%39%21%14%4
1731
May1st to 15thNight
46%313%23%13%
1620
16th to endNight
36%5%14%21%18%3
1506
June1st to 15thNight
34%211%27%20%3
1440
16th to endNight
36%414%23%18%2
1440
July1st to 15thNight
31%313%28%18%3
1360
16th to endNight
27%415%29%18%4
1417
August1st to 15thNight
25%316%30%20%2
1593
16th to endNight
30%411%27%20%5%
1910
September1st to 15thNight
29%49%27%24%4
1815
16th to endNight
32%38%30%21%3
1870
October1st to 15thNight
34%38%28%23%1
1881
16th to endNight
46%210%25%14%1
2244
November1st to 15thNight
39%28%26%18%4
2276
16th to endNight
49%212%24%11%
2346
December1st to 15thNight
57%111%18%9%
2520
16th to endNight
67%28%14%5%
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
28%7%32%22%8%
90
16th to endDay
17%13%35%25%7%1
96
February1st to 15thDay
22%18%44%12%2
90
16th to endDay
16%16%33%20%11%2
81
March1st to 15thDay
36%14%23%21%4
90
16th to endDay
25%11%29%21%8%2
252
April1st to 15thDay
23%12%28%22%10%2
270
16th to endDay
21%9%31%22%9%5%
270
May1st to 15thDay
23%8%29%20%13%4
288
16th to endDay
15%6%33%23%16%4
506
June1st to 15thDay
12%328%30%18%6%
495
16th to endDay
11%7%31%28%14%5%
495
July1st to 15thDay
11%424%26%18%13%
475
16th to endDay
7%122%31%23%12%
515
August1st to 15thDay
8%113%31%26%17%
376
16th to endDay
9%314%29%25%17%
332
September1st to 15thDay
13%313%29%29%9%
315
16th to endDay
9%416%28%30%10%
270
October1st to 15thDay
15%325%26%22%6%
186
16th to endDay
22%8%40%23%4
96
November1st to 15thDay
8%8%25%25%22%8%
90
16th to endDay
40%6%32%13%7%
90
December1st to 15thDay
17%16%35%21%7%1
90
16th to endDay
31%19%42%42
96
January1st to 15thNight
24%14%35%20%5%
900
16th to endNight
20%12%34%28%3
960
February1st to 15thNight
22%11%36%24%4
776
16th to endNight
22%12%33%25%6%
631
March1st to 15thNight
25%10%33%23%6%
720
16th to endNight
20%7%35%26%9%
639
April1st to 15thNight
19%10%36%26%6%
539
16th to endNight
21%8%30%28%9%
540
May1st to 15thNight
21%430%30%12%1
540
16th to endNight
10%325%39%19%1
563
June1st to 15thNight
11%323%45%14%
540
16th to endNight
10%226%38%20%1
540
July1st to 15thNight
9%118%43%24%2
510
16th to endNight
5%212%43%32%3
564
August1st to 15thNight
5%16%50%30%5%
539
16th to endNight
9%213%36%34%4
573
September1st to 15thNight
12%311%38%28%5%
555
16th to endNight
9%417%33%29%4
677
October1st to 15thNight
14%6%22%35%19%1
660
16th to endNight
23%11%30%24%9%
704
November1st to 15thNight
15%12%34%25%10%1
700
16th to endNight
23%11%32%23%8%
726
December1st to 15thNight
27%11%31%23%5%
900
16th to endNight
30%10%32%23%3
960
Page generated at 2017-09-21 06:18:22. Version ac04

Copyright 2017 A. Danko


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