East Central Community College
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the East Central Community College clear sky chart from 2005-11-06 to 2024-01-14.

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
49%
23542
24%
74247
18%
23488
57%
23488
29%
44583

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
27%
950
24%
2492
8%
946
39%
946
29%
1615
January11th to 20thNight
30%
898
24%
2366
10%
898
39%
898
23%
1609
January21st to endNight
24%
792
28%
2376
11%
792
40%
792
23%
1531
February1st to 10thNight
31%
720
23%
2160
12%
720
41%
720
24%
1410
February11th to 20thNight
28%
703
21%
2099
10%
700
37%
700
23%
1373
February21st to endNight
19%
592
21%
1776
7%
592
30%
592
20%
1215
March1st to 10thNight
32%
720
24%
2160
12%
720
41%
720
28%
1312
March11th to 20thNight
33%
594
19%
2034
12%
594
43%
594
22%
1284
March21st to endNight
35%
594
25%
2009
16%
594
47%
594
27%
1173
April1st to 10thNight
37%
540
25%
1800
17%
540
48%
540
26%
1064
April11th to 20thNight
37%
533
26%
1775
18%
533
50%
533
28%
1026
April21st to endNight
47%
540
30%
1800
22%
540
61%
540
37%
948
May1st to 10thNight
55%
540
26%
1800
19%
540
65%
540
38%
960
May11th to 20thNight
59%
531
21%
1699
18%
531
65%
531
32%
988
May21st to endNight
69%
582
23%
1744
20%
582
73%
582
37%
1026
June1st to 10thNight
68%
540
18%
1620
17%
540
69%
540
31%
1013
June11th to 20thNight
76%
540
24%
1441
21%
540
77%
540
42%
851
June21st to endNight
72%
540
20%
1440
18%
540
73%
540
36%
894
July1st to 10thNight
76%
525
18%
1415
17%
525
76%
525
33%
913
July11th to 20thNight
78%
522
15%
1588
16%
522
79%
522
33%
961
July21st to endNight
77%
591
15%
1858
18%
558
78%
558
32%
1094
August1st to 10thNight
82%
537
16%
1778
20%
534
83%
534
37%
985
August11th to 20thNight
76%
534
18%
1776
22%
534
77%
534
29%
1072
August21st to endNight
71%
594
19%
1980
22%
594
72%
594
27%
1237
September1st to 10thNight
70%
540
25%
1800
27%
540
71%
540
29%
1077
September11th to 20thNight
66%
626
24%
1886
23%
626
68%
626
31%
1156
September21st to endNight
67%
720
31%
1980
26%
720
70%
720
39%
1166
October1st to 10thNight
65%
720
32%
1980
24%
720
70%
720
44%
1098
October11th to 20thNight
55%
720
33%
2150
24%
720
64%
720
37%
1214
October21st to endNight
51%
792
33%
2376
27%
792
58%
792
36%
1359
November1st to 10thNight
56%
740
31%
2334
25%
740
65%
740
38%
1264
November11th to 20thNight
45%
760
30%
2470
24%
760
55%
760
34%
1366
November21st to endNight
43%
760
27%
2470
20%
760
54%
760
28%
1459
December1st to 10thNight
36%
760
25%
2470
17%
760
48%
760
25%
1515
December11th to 20thNight
32%
759
24%
2903
15%
758
43%
758
21%
1768
December21st to endNight
27%
893
14%
4442
11%
883
37%
883
14%
2587

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%35%5%5%7%42%
74920
Night
12%6%25%5%3445%7%47%
74796
TransparencyDay
41%410%20%19%6%
74652
Night
37%411%20%21%8%
74585
SeeingDay
15%8%20%25%22%11%
13779
Night
15%7%22%29%22%5%
23554

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%8%24423435%45%
1669
11th to 20thDay
20%8%34423336%42%
1660
21st to endDay
18%7%24333445%47%
1980
February1st to 10thDay
18%9%45%6%24446%38%
1800
11th to 20thDay
21%8%45%422245%41%
1748
21st to endDay
17%8%47%5%35%436%38%
1480
March1st to 10thDay
16%7%36%5%34445%43%
1800
11th to 20thDay
16%6%36%6%45%5%46%39%
1939
21st to endDay
12%6%35%5%36%5%5%6%43%
2344
April1st to 10thDay
12%435%5%36%5%5%7%45%
2160
11th to 20thDay
13%7%35%5%2445%6%45%
2134
21st to endDay
9%425%5%35%46%8%49%
2160
May1st to 10thDay
13%4345%25%5%5%7%47%
2160
11th to 20thDay
9%6%26%8%46%6%5%9%39%
2190
21st to endDay
7%5%37%6%46%5%6%10%41%
2531
June1st to 10thDay
10%6%36%7%47%6%7%9%36%
2340
11th to 20thDay
5%435%7%47%8%8%9%41%
2511
21st to endDay
6%5%36%7%5%7%7%8%10%37%
2520
July1st to 10thDay
8%6%38%7%5%7%8%8%9%31%
2499
11th to 20thDay
8%6%37%7%48%7%9%10%29%
2314
21st to endDay
7%438%9%6%8%8%6%11%30%
2350
August1st to 10thDay
5%426%7%5%7%8%10%10%36%
2148
11th to 20thDay
7%5%38%8%5%7%7%8%8%33%
2125
21st to endDay
13%5%25%6%47%7%6%8%36%
2376
September1st to 10thDay
10%5%27%8%46%6%6%7%39%
2160
11th to 20thDay
13%6%26%5%35%5%5%7%44%
2054
21st to endDay
11%4235%3445%7%52%
1980
October1st to 10thDay
7%5%34433345%57%
1980
11th to 20thDay
10%42442346%7%53%
1805
21st to endDay
12%5%24423336%56%
1980
November1st to 10thDay
10%5%24433446%56%
1740
11th to 20thDay
13%6%25%424345%53%
1710
21st to endDay
15%6%35%43345%6%46%
1710
December1st to 10thDay
16%7%36%42445%8%41%
1710
11th to 20thDay
14%9%36%5%35%435%43%
2153
21st to endDay
14%8%36%5%4445%7%41%
3000
January1st to 10thNight
18%8%34423345%46%
2492
11th to 20thNight
18%9%46%423445%42%
2366
21st to endNight
18%8%25%433345%45%
2376
February1st to 10thNight
17%7%35%4345%5%5%41%
2160
11th to 20thNight
21%6%34423445%43%
2098
21st to endNight
21%7%36%5%35%446%37%
1776
March1st to 10thNight
14%7%35%42345%7%46%
2160
11th to 20thNight
16%6%35%435%45%7%41%
2034
21st to endNight
13%6%25%5%245%5%6%47%
2009
April1st to 10thNight
11%5%26%5%335%5%6%48%
1800
11th to 20thNight
14%5%25%42445%6%47%
1775
21st to endNight
8%3245%3446%8%54%
1800
May1st to 10thNight
9%5%2442335%8%55%
1800
11th to 20thNight
7%5%25%6%3447%10%46%
1699
21st to endNight
7%4145%36%6%6%12%47%
1744
June1st to 10thNight
6%426%5%5%6%5%7%12%41%
1620
11th to 20thNight
32235%36%6%8%11%50%
1441
21st to endNight
45%246%36%6%7%13%43%
1440
July1st to 10thNight
5%325%7%46%6%10%12%40%
1455
11th to 20thNight
5%325%5%46%6%8%11%43%
1642
21st to endNight
4435%5%46%8%9%11%42%
1968
August1st to 10thNight
33245%35%8%9%13%44%
1790
11th to 20thNight
6%425%6%45%6%6%13%41%
1776
21st to endNight
9%5%25%6%35%6%7%9%42%
1980
September1st to 10thNight
9%5%36%5%35%5%7%9%45%
1800
11th to 20thNight
9%6%345%35%46%6%48%
1886
21st to endNight
8%5%244345%6%7%52%
1980
October1st to 10thNight
7%32442436%7%59%
1980
11th to 20thNight
11%425%323447%54%
2150
21st to endNight
14%7%3332233457%
2376
November1st to 10thNight
11%414323445%59%
2334
11th to 20thNight
13%5%23423446%54%
2470
21st to endNight
14%7%2442445%6%48%
2470
December1st to 10thNight
18%6%25%43345%7%44%
2470
11th to 20thNight
15%7%36%5%33345%46%
3042
21st to endNight
17%10%25%43345%7%41%
4637

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
44%2420%24%6%
1670
11th to 20thDay
46%2417%22%8%
1660
21st to endDay
41%2419%27%7%
1980
February1st to 10thDay
48%37%17%17%9%
1800
11th to 20thDay
48%15%19%20%8%
1758
21st to endDay
48%36%15%18%9%
1480
March1st to 10thDay
44%46%16%20%10%
1800
11th to 20thDay
47%38%15%19%7%
1939
21st to endDay
42%28%22%21%4
2344
April1st to 10thDay
39%39%21%21%7%
2160
11th to 20thDay
41%26%19%25%7%
2134
21st to endDay
34%49%25%25%4
2160
May1st to 10thDay
37%39%24%22%5%
2160
11th to 20thDay
40%5%14%24%16%1
2194
21st to endDay
39%413%26%17%1
2531
June1st to 10thDay
43%5%13%23%14%2
2340
11th to 20thDay
36%6%15%25%14%3
2511
21st to endDay
40%7%15%24%13%3
2520
July1st to 10thDay
45%8%17%20%8%2
2431
11th to 20thDay
45%8%21%18%7%1
2245
21st to endDay
45%7%19%21%8%1
2219
August1st to 10thDay
38%8%20%26%8%
2136
11th to 20thDay
45%8%18%17%9%3
2125
21st to endDay
43%8%15%18%11%5%
2376
September1st to 10thDay
42%5%12%18%17%6%
2160
11th to 20thDay
40%5%11%17%21%6%
2054
21st to endDay
34%310%22%22%9%
1980
October1st to 10thDay
31%37%20%28%11%
1980
11th to 20thDay
32%35%20%29%11%
1805
21st to endDay
33%2419%31%12%
1980
November1st to 10thDay
32%26%19%29%12%
1740
11th to 20thDay
35%26%16%27%14%
1710
21st to endDay
40%37%17%23%10%
1710
December1st to 10thDay
43%39%18%19%8%
1710
11th to 20thDay
47%25%15%25%6%
2150
21st to endDay
46%1422%23%3
3000
January1st to 10thNight
42%17%16%28%6%
2492
11th to 20thNight
46%2419%20%8%
2366
21st to endNight
44%2315%27%8%
2376
February1st to 10thNight
44%37%17%20%9%
2160
11th to 20thNight
44%35%17%21%10%
2099
21st to endNight
49%35%15%16%12%
1776
March1st to 10thNight
39%27%16%23%13%
2160
11th to 20thNight
44%410%16%19%7%
2034
21st to endNight
38%410%22%21%7%
2009
April1st to 10thNight
38%411%19%20%9%
1800
11th to 20thNight
37%28%20%22%10%
1775
21st to endNight
29%39%25%28%6%
1800
May1st to 10thNight
30%39%29%23%7%
1800
11th to 20thNight
34%5%16%25%19%2
1700
21st to endNight
31%6%14%25%21%3
1745
June1st to 10thNight
36%7%15%26%14%2
1620
11th to 20thNight
26%7%17%31%14%5%
1441
21st to endNight
32%7%19%23%15%3
1440
July1st to 10thNight
34%9%22%24%8%3
1415
11th to 20thNight
31%10%27%24%7%1
1588
21st to endNight
31%9%26%24%8%2
1858
August1st to 10thNight
26%9%28%27%10%1
1778
11th to 20thNight
34%9%22%19%12%4
1776
21st to endNight
37%8%20%19%11%4
1980
September1st to 10thNight
36%6%15%19%18%6%
1800
11th to 20thNight
37%5%13%17%19%8%
1886
21st to endNight
31%48%25%22%9%
1980
October1st to 10thNight
26%49%20%24%16%
1980
11th to 20thNight
31%35%19%28%13%
2150
21st to endNight
34%25%16%26%17%
2376
November1st to 10thNight
29%37%17%29%15%
2334
11th to 20thNight
33%26%17%28%14%
2470
21st to endNight
39%36%21%20%12%
2470
December1st to 10thNight
41%311%17%22%6%
2470
11th to 20thNight
43%26%14%29%7%
3044
21st to endNight
46%15%16%29%4
4637

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
26%19%36%16%31
270
11th to 20thDay
27%17%33%15%8%1
249
21st to endDay
24%22%34%15%31
264
February1st to 10thDay
26%19%35%15%5%
240
11th to 20thDay
35%19%30%12%4
240
21st to endDay
25%24%37%13%1
198
March1st to 10thDay
24%20%36%14%5%
240
11th to 20thDay
27%20%32%17%4
240
21st to endDay
22%16%31%24%8%
430
April1st to 10thDay
19%13%30%25%11%1
420
11th to 20thDay
23%15%24%26%11%3
412
21st to endDay
12%12%31%29%15%2
420
May1st to 10thDay
16%9%23%31%17%4
423
11th to 20thDay
10%421%34%18%13%
447
21st to endDay
9%420%29%23%16%
485
June1st to 10thDay
14%215%28%26%14%
450
11th to 20thDay
6%311%32%35%13%
621
21st to endDay
8%212%31%31%16%
630
July1st to 10thDay
7%38%27%38%18%
621
11th to 20thDay
9%25%21%37%26%
592
21st to endDay
6%26%22%39%25%
488
August1st to 10thDay
7%17%19%37%28%
446
11th to 20thDay
8%2422%38%25%
439
21st to endDay
15%46%21%31%23%
495
September1st to 10thDay
10%18%31%34%16%
450
11th to 20thDay
11%312%25%32%18%
450
21st to endDay
13%212%29%32%11%
450
October1st to 10thDay
9%5%21%32%26%8%
450
11th to 20thDay
9%8%27%34%19%5%
275
21st to endDay
19%11%22%32%11%4
297
November1st to 10thDay
20%9%27%29%10%5%
270
11th to 20thDay
19%11%36%21%12%1
270
21st to endDay
15%16%36%20%10%3
270
December1st to 10thDay
25%12%36%19%7%1
270
11th to 20thDay
19%14%40%21%6%
270
21st to endDay
26%15%33%22%41
297
January1st to 10thNight
24%13%32%25%6%
950
11th to 20thNight
23%13%29%27%7%
898
21st to endNight
23%13%36%25%3
792
February1st to 10thNight
25%11%28%32%4
720
11th to 20thNight
26%14%30%26%5%
703
21st to endNight
23%15%38%21%2
592
March1st to 10thNight
19%13%33%27%8%
720
11th to 20thNight
21%10%33%27%9%1
594
21st to endNight
16%10%36%26%11%1
594
April1st to 10thNight
16%10%33%27%14%1
540
11th to 20thNight
16%10%31%28%13%1
533
21st to endNight
10%6%32%37%14%1
540
May1st to 10thNight
10%5%24%39%20%2
540
11th to 20thNight
9%220%42%24%4
531
21st to endNight
8%213%34%35%9%
584
June1st to 10thNight
8%111%36%38%7%
540
11th to 20thNight
429%27%47%11%
540
21st to endNight
6%29%26%42%14%
540
July1st to 10thNight
6%1426%49%14%
525
11th to 20thNight
5%1323%47%20%
522
21st to endNight
415%25%50%15%
591
August1st to 10thNight
5%1320%50%21%
537
11th to 20thNight
7%2324%48%16%
534
21st to endNight
12%16%21%43%17%
594
September1st to 10thNight
12%25%31%39%11%
540
11th to 20thNight
12%39%27%42%7%
626
21st to endNight
11%210%34%39%5%
720
October1st to 10thNight
8%318%32%34%6%
720
11th to 20thNight
13%5%20%34%25%3
720
21st to endNight
18%7%20%33%21%2
792
November1st to 10thNight
13%6%19%38%21%4
740
11th to 20thNight
16%7%28%34%15%1
760
21st to endNight
18%8%25%33%15%1
760
December1st to 10thNight
21%10%28%30%10%
760
11th to 20thNight
22%8%32%28%10%
760
21st to endNight
26%12%30%27%5%
902
Page generated at 2024-01-11 03:22:37. Version ac07

Copyright 2024 Attilla Danko


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