Peoria
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peoria clear sky chart from 2005-11-05 to 2017-08-12.

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%
15821
19%
46491
11%
15777
45%
15777
26%
30185

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
23%
900
16%
2506
5%
895
32%
895
20%
1765
January16th to endNight
20%
960
15%
2571
4%
960
28%
960
19%
1851
February1st to 15thNight
23%
834
14%
2244
4%
833
31%
833
20%
1608
February16th to endNight
23%
631
21%
1893
7%
631
34%
631
22%
1258
March1st to 15thNight
26%
702
16%
2142
8%
702
33%
702
19%
1451
March16th to endNight
26%
576
14%
2007
8%
576
35%
576
18%
1349
April1st to 15thNight
29%
539
18%
1797
12%
539
40%
539
22%
1145
April16th to endNight
35%
540
18%
1800
14%
540
44%
540
21%
1194
May1st to 15thNight
37%
540
17%
1566
11%
540
44%
540
23%
1072
May16th to endNight
48%
563
19%
1497
11%
561
54%
561
31%
984
June1st to 15thNight
55%
540
19%
1440
12%
540
59%
540
39%
876
June16th to endNight
51%
540
18%
1440
10%
540
55%
540
35%
906
July1st to 15thNight
63%
510
18%
1360
13%
510
65%
510
40%
810
July16th to endNight
73%
564
26%
1417
19%
531
77%
531
46%
800
August1st to 15thNight
74%
527
24%
1605
25%
524
75%
524
43%
856
August16th to endNight
68%
525
22%
1750
22%
525
73%
525
35%
968
September1st to 15thNight
62%
495
30%
1650
30%
495
67%
495
35%
897
September16th to endNight
59%
625
28%
1783
19%
625
65%
625
35%
1043
October1st to 15thNight
50%
660
29%
1952
21%
660
58%
660
35%
1136
October16th to endNight
31%
704
20%
2181
12%
704
40%
704
27%
1344
November1st to 15thNight
32%
700
26%
2276
15%
700
46%
700
27%
1339
November16th to endNight
27%
786
20%
2406
10%
786
37%
786
23%
1560
December1st to 15thNight
22%
900
13%
2520
5%
900
29%
900
19%
1829
December16th to endNight
19%
960
12%
2688
4%
960
27%
960
13%
2144

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%35%5%3445%7%38%
47488
Night
13%7%35%424346%41%
46660
Cloud CoverDay
14%7%35%5%3445%7%38%
47496
Night
13%7%35%424446%41%
46665
TransparencyDay
45%412%22%12%1
47174
Night
42%411%24%14%2
46492
SeeingDay
15%9%25%26%17%5%
5804
Night
17%8%29%30%12%1
15823

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
14%13%6%11%6%35%235%27%
1432
16th to endDay
14%15%6%8%5%3344428%
1651
February1st to 15thDay
14%13%6%8%5%24345%31%
1618
16th to endDay
13%11%6%7%6%35%446%32%
1580
March1st to 15thDay
15%12%47%434445%33%
1818
16th to endDay
17%11%46%5%2445%7%29%
2217
April1st to 15thDay
17%8%45%5%24335%37%
2151
16th to endDay
20%8%35%5%2345%6%35%
2160
May1st to 15thDay
21%7%25%5%33447%32%
2381
16th to endDay
16%5%25%5%35%45%6%37%
2617
June1st to 15thDay
11%425%5%35%45%7%43%
2520
16th to endDay
10%5%25%5%36%5%6%8%40%
2520
July1st to 15thDay
8%4245%36%5%6%10%42%
2520
16th to endDay
6%4246%35%5%7%9%43%
2655
August1st to 15thDay
8%4245%35%46%10%44%
2256
16th to endDay
9%42443447%8%45%
2100
September1st to 15thDay
14%42442335%7%47%
1980
16th to endDay
9%4244245%5%6%48%
1834
October1st to 15thDay
15%6%1442224449%
1678
16th to endDay
18%7%25%323435%42%
1691
November1st to 15thDay
16%6%14424346%45%
1582
16th to endDay
18%9%36%42343438%
1551
December1st to 15thDay
20%11%45%6%36%445%27%
1440
16th to endDay
20%14%5%5%5%24336%27%
1536
January1st to 15thNight
14%10%37%5%44345%36%
2506
16th to endNight
13%12%7%7%5%33346%32%
2571
February1st to 15thNight
14%10%5%7%434435%34%
2242
16th to endNight
14%9%46%424345%40%
1893
March1st to 15thNight
15%10%46%424436%36%
2129
16th to endNight
16%8%46%5%25%45%8%33%
2007
April1st to 15thNight
15%8%35%42445%5%41%
1797
16th to endNight
19%6%246%24246%38%
1800
May1st to 15thNight
19%6%35%5%1435%7%37%
1566
16th to endNight
9%426%5%35%5%5%8%43%
1496
June1st to 15thNight
10%5%2342345%7%50%
1440
16th to endNight
8%425%445%45%8%45%
1440
July1st to 15thNight
7%314425%5%6%11%47%
1440
16th to endNight
3323425%5%6%10%52%
1513
August1st to 15thNight
5%21333445%9%55%
1614
16th to endNight
7%414424447%53%
1750
September1st to 15thNight
12%31432324456%
1650
16th to endNight
7%4244345%5%8%49%
1783
October1st to 15thNight
11%324324346%52%
1952
16th to endNight
17%6%24323346%44%
2181
November1st to 15thNight
12%6%34423335%50%
2276
16th to endNight
17%7%35%423346%39%
2406
December1st to 15thNight
20%11%46%423346%32%
2520
16th to endNight
23%14%5%7%5%25%23424%
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
14%13%5%10%7%35%245%26%
1432
16th to endDay
14%15%6%8%6%33445%27%
1651
February1st to 15thDay
14%12%6%8%5%24336%31%
1618
16th to endDay
12%11%5%7%6%25%446%32%
1580
March1st to 15thDay
15%11%47%5%3345%5%33%
1828
16th to endDay
16%10%36%5%3446%7%29%
2215
April1st to 15thDay
17%8%45%6%24436%36%
2151
16th to endDay
20%8%25%5%33446%35%
2160
May1st to 15thDay
20%7%36%5%2435%7%32%
2381
16th to endDay
16%6%25%5%45%45%6%37%
2617
June1st to 15thDay
10%5%35%6%35%447%43%
2520
16th to endDay
10%5%35%5%35%5%6%8%40%
2520
July1st to 15thDay
8%4245%35%6%6%10%43%
2520
16th to endDay
6%3236%45%5%8%9%43%
2655
August1st to 15thDay
7%4245%3446%10%44%
2256
16th to endDay
9%4245%35%47%7%45%
2100
September1st to 15thDay
13%415%43335%7%46%
1980
16th to endDay
9%425%5%245%5%7%47%
1834
October1st to 15thDay
15%6%24423345%48%
1678
16th to endDay
17%8%25%324335%41%
1691
November1st to 15thDay
16%7%13434346%45%
1582
16th to endDay
18%10%36%432425%38%
1551
December1st to 15thDay
20%10%5%6%6%36%5%45%27%
1440
16th to endDay
20%13%6%6%5%23436%27%
1536
January1st to 15thNight
13%10%37%5%44345%36%
2506
16th to endNight
13%12%7%7%5%33346%32%
2571
February1st to 15thNight
14%10%5%7%5%34435%34%
2235
16th to endNight
14%9%46%423346%39%
1893
March1st to 15thNight
15%10%46%424446%36%
2142
16th to endNight
16%8%46%5%25%45%8%32%
2007
April1st to 15thNight
15%8%35%42445%5%40%
1797
16th to endNight
19%7%25%6%23346%37%
1800
May1st to 15thNight
18%7%35%42445%7%36%
1565
16th to endNight
9%435%5%36%5%5%8%42%
1496
June1st to 15thNight
10%5%23323447%49%
1440
16th to endNight
8%5%25%5%35%45%8%45%
1440
July1st to 15thNight
6%3234345%6%11%48%
1440
16th to endNight
33134245%6%10%52%
1513
August1st to 15thNight
5%2143245%5%9%54%
1614
16th to endNight
6%41442445%7%53%
1750
September1st to 15thNight
12%323413335%56%
1650
16th to endNight
7%4244245%5%8%49%
1783
October1st to 15thNight
10%414324346%52%
1952
16th to endNight
17%7%25%32335%6%44%
2181
November1st to 15thNight
12%6%24423335%50%
2276
16th to endNight
16%7%35%423446%39%
2406
December1st to 15thNight
20%11%5%6%423336%32%
2520
16th to endNight
22%14%6%7%5%2433424%
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%29%15%9%
1433
16th to endDay
59%313%16%6%
1651
February1st to 15thDay
55%315%18%6%
1620
16th to endDay
53%412%21%7%
1580
March1st to 15thDay
52%415%21%6%
1828
16th to endDay
52%5%15%20%41
2217
April1st to 15thDay
49%210%23%11%1
2151
16th to endDay
49%411%19%12%2
2160
May1st to 15thDay
50%413%21%8%
2381
16th to endDay
45%6%12%18%15%1
2621
June1st to 15thDay
38%5%11%25%15%2
2520
16th to endDay
39%7%11%21%16%3
2520
July1st to 15thDay
36%6%14%24%15%3
2371
16th to endDay
32%7%17%27%13%1
2488
August1st to 15thDay
33%5%15%26%17%1
2241
16th to endDay
34%6%11%26%17%4
2100
September1st to 15thDay
36%49%24%21%4
1980
16th to endDay
34%49%28%19%2
1834
October1st to 15thDay
37%39%28%18%2
1678
16th to endDay
44%312%23%13%2
1691
November1st to 15thDay
40%311%25%16%2
1582
16th to endDay
49%313%24%9%
1551
December1st to 15thDay
58%412%18%6%
1440
16th to endDay
60%310%16%8%
1536
January1st to 15thNight
50%312%21%12%
2506
16th to endNight
53%216%20%7%
2571
February1st to 15thNight
51%313%20%9%1
2244
16th to endNight
46%312%26%10%
1893
March1st to 15thNight
49%312%23%9%1
2142
16th to endNight
48%5%14%20%9%1
2007
April1st to 15thNight
44%39%26%13%2
1797
16th to endNight
47%49%21%12%4
1800
May1st to 15thNight
46%5%12%21%14%
1566
16th to endNight
37%6%13%19%18%3
1498
June1st to 15thNight
32%412%27%19%4
1440
16th to endNight
35%413%22%19%4
1440
July1st to 15thNight
30%5%13%29%18%3
1360
16th to endNight
24%5%16%32%18%2
1417
August1st to 15thNight
24%5%14%31%20%3
1605
16th to endNight
29%6%10%28%19%5%
1750
September1st to 15thNight
31%37%27%24%5%
1650
16th to endNight
30%5%10%27%22%3
1783
October1st to 15thNight
32%39%27%22%4
1952
16th to endNight
40%211%25%18%2
2181
November1st to 15thNight
36%39%24%20%4
2276
16th to endNight
45%212%26%12%
2406
December1st to 15thNight
54%213%20%8%
2520
16th to endNight
64%38%15%7%
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
34%18%23%21%2
90
16th to endDay
16%28%34%11%9%
96
February1st to 15thDay
21%24%37%12%4
90
16th to endDay
17%19%30%22%9%
81
March1st to 15thDay
32%26%31%7%2
90
16th to endDay
23%15%25%24%8%1
201
April1st to 15thDay
16%13%35%25%8%
270
16th to endDay
22%9%28%21%14%2
270
May1st to 15thDay
23%13%29%21%8%4
345
16th to endDay
19%10%28%23%11%6%
517
June1st to 15thDay
10%5%30%28%21%3
495
16th to endDay
13%7%31%27%15%5%
495
July1st to 15thDay
12%322%31%17%11%
475
16th to endDay
6%117%36%29%8%
515
August1st to 15thDay
8%216%31%28%12%
417
16th to endDay
10%111%30%32%12%
268
September1st to 15thDay
13%311%32%31%6%
255
16th to endDay
9%8%15%29%27%9%
254
October1st to 15thDay
11%16%22%29%16%5%
118
16th to endDay
25%8%38%23%4
96
November1st to 15thDay
5%8%32%31%17%4
90
16th to endDay
36%17%32%10%3
90
December1st to 15thDay
22%22%26%21%5%2
90
16th to endDay
30%29%33%7%
96
January1st to 15thNight
18%14%39%22%5%
900
16th to endNight
19%12%38%25%3
960
February1st to 15thNight
19%12%36%26%5%
836
16th to endNight
20%13%39%24%2
631
March1st to 15thNight
21%10%37%24%6%
702
16th to endNight
19%10%36%24%9%
576
April1st to 15thNight
18%13%34%25%7%
539
16th to endNight
21%9%28%28%11%
540
May1st to 15thNight
22%6%27%34%8%
540
16th to endNight
11%329%38%15%1
563
June1st to 15thNight
12%222%46%14%
540
16th to endNight
9%228%39%18%1
540
July1st to 15thNight
7%219%40%28%2
510
16th to endNight
5%110%44%34%2
564
August1st to 15thNight
6%19%45%29%7%
527
16th to endNight
8%14%40%32%3
525
September1st to 15thNight
14%213%35%29%4
495
16th to endNight
8%5%19%35%26%4
625
October1st to 15thNight
12%6%25%34%18%2
660
16th to endNight
20%9%34%25%8%
704
November1st to 15thNight
16%9%36%26%10%
700
16th to endNight
20%13%33%25%6%
786
December1st to 15thNight
26%12%32%23%5%
900
16th to endNight
31%10%30%24%2
960
Page generated at 2017-08-13 13:16:34. Version ac04

Copyright 2017 A. Danko


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