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 2018-01-20.

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%
16492
19%
48459
11%
16450
45%
16450
25%
31898

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%
975
14%
2716
5%
970
29%
970
18%
1959
January16th to endNight
21%
985
15%
2724
6%
985
29%
985
18%
2022
February1st to 15thNight
22%
773
14%
2184
4%
773
30%
773
19%
1552
February16th to endNight
25%
631
18%
1893
7%
631
34%
631
18%
1332
March1st to 15thNight
25%
720
14%
2160
9%
720
30%
720
18%
1522
March16th to endNight
29%
639
16%
2019
9%
639
37%
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
53%
562
18%
1505
10%
561
58%
561
33%
961
June1st to 15thNight
51%
540
18%
1440
11%
540
56%
540
38%
882
June16th to endNight
50%
540
18%
1440
10%
540
55%
540
34%
911
July1st to 15thNight
62%
510
18%
1360
12%
510
66%
510
40%
812
July16th to endNight
70%
564
23%
1417
18%
531
73%
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%
717
30%
1980
23%
717
65%
717
39%
1154
October1st to 15thNight
48%
720
27%
2052
20%
720
55%
720
32%
1255
October16th to endNight
29%
768
20%
2448
13%
768
38%
768
22%
1563
November1st to 15thNight
31%
760
24%
2471
15%
760
42%
760
25%
1500
November16th to endNight
26%
787
20%
2542
11%
787
37%
787
20%
1660
December1st to 15thNight
21%
975
13%
2730
4%
975
29%
975
18%
1984
December16th to endNight
17%
1040
11%
2912
3%
1040
24%
1040
12%
2346

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%
49072
Night
14%8%35%5%24446%39%
48628
Cloud CoverDay
14%7%36%5%3445%7%36%
49081
Night
14%7%36%424446%39%
48633
TransparencyDay
46%312%22%12%1
48758
Night
44%311%23%14%2
48460
SeeingDay
15%6%26%25%17%7%
6341
Night
18%8%28%30%13%1
16496

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%25%
1552
16th to endDay
13%16%7%9%5%24436%26%
1601
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
8%5%25%5%345%6%8%45%
1980
October1st to 15thDay
15%7%25%42435%6%42%
1905
16th to endDay
18%7%26%5%33447%35%
1776
November1st to 15thDay
16%6%24424447%42%
1717
16th to endDay
18%8%46%423346%37%
1745
December1st to 15thDay
17%12%48%6%25%345%28%
1560
16th to endDay
21%14%5%8%5%24436%22%
1664
January1st to 15thNight
18%12%46%6%23445%32%
2716
16th to endNight
14%11%6%8%6%34345%29%
2724
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%46%7%50%
1980
October1st to 15thNight
12%5%24424347%49%
2052
16th to endNight
18%8%25%423245%41%
2448
November1st to 15thNight
13%6%35%5%23347%43%
2471
16th to endNight
17%8%35%434346%38%
2542
December1st to 15thNight
19%10%48%5%24335%32%
2730
16th to endNight
22%15%5%8%7%35%33421%
2912

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%6%34446%25%
1552
16th to endDay
13%16%7%8%6%24336%25%
1601
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%425%5%345%5%8%45%
1980
October1st to 15thDay
15%6%25%42435%6%42%
1905
16th to endDay
19%6%25%5%3335%6%35%
1776
November1st to 15thDay
16%6%2442445%6%42%
1717
16th to endDay
18%8%46%423346%37%
1745
December1st to 15thDay
17%13%38%6%35%345%28%
1560
16th to endDay
22%14%6%7%5%34345%22%
1664
January1st to 15thNight
18%11%46%5%23445%33%
2716
16th to endNight
14%11%6%9%6%34345%29%
2724
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%
1980
October1st to 15thNight
13%5%24324337%49%
2052
16th to endNight
18%8%35%423245%41%
2448
November1st to 15thNight
13%6%35%5%23346%44%
2471
16th to endNight
17%8%35%424336%38%
2542
December1st to 15thNight
19%10%48%5%24335%32%
2730
16th to endNight
22%14%5%8%6%35%33421%
2912

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
59%211%15%8%1
1553
16th to endDay
60%212%16%6%
1601
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
34%38%29%21%2
1980
October1st to 15thDay
42%310%27%13%2
1905
16th to endDay
48%312%22%11%1
1776
November1st to 15thDay
41%213%23%16%2
1717
16th to endDay
48%212%26%10%
1745
December1st to 15thDay
59%210%19%8%
1560
16th to endDay
64%311%13%6%
1664
January1st to 15thNight
54%211%18%12%1
2716
16th to endNight
57%113%18%8%
2724
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
31%38%31%22%3
1980
October1st to 15thNight
35%37%27%22%2
2052
16th to endNight
45%29%25%15%1
2448
November1st to 15thNight
40%28%26%17%4
2471
16th to endNight
47%212%25%11%
2542
December1st to 15thNight
55%111%19%10%
2730
16th to endNight
66%28%14%6%
2912

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%33%23%7%
135
16th to endDay
16%11%37%26%6%
109
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
7%417%28%29%11%
314
October1st to 15thDay
19%325%26%20%5%
240
16th to endDay
25%7%36%25%6%
144
November1st to 15thDay
17%7%28%21%16%8%
135
16th to endDay
30%7%38%16%7%
135
December1st to 15thDay
15%20%36%18%8%
135
16th to endDay
24%19%45%9%1
144
January1st to 15thNight
24%13%35%21%5%
975
16th to endNight
20%12%35%28%3
985
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%418%33%30%4
717
October1st to 15thNight
15%6%23%35%18%1
720
16th to endNight
23%11%30%23%9%
768
November1st to 15thNight
16%11%35%24%10%1
760
16th to endNight
22%11%33%23%8%
787
December1st to 15thNight
26%11%32%23%5%
975
16th to endNight
29%10%32%23%3
1040
Page generated at 2018-01-21 11:19:21. Version ac04

Copyright 2018 A. Danko


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