Cedar Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cedar Falls clear sky chart from 2005-11-06 to 2024-02-10.

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
37%
24816
17%
80254
10%
24717
44%
24717
22%
53684

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
26%
940
9%
4412
6%
926
34%
926
11%
3373
January11th to 20thNight
24%
949
13%
4224
5%
930
30%
930
10%
3055
January21st to endNight
22%
1036
8%
4505
4%
1023
28%
1023
9%
3566
February1st to 10thNight
25%
948
13%
2464
5%
948
29%
948
19%
1826
February11th to 20thNight
26%
879
17%
2274
6%
875
33%
875
25%
1576
February21st to endNight
24%
614
19%
1798
5%
614
35%
614
19%
1258
March1st to 10thNight
29%
619
17%
2059
10%
619
37%
619
21%
1347
March11th to 20thNight
30%
540
19%
1980
13%
540
41%
540
20%
1269
March21st to endNight
24%
594
10%
2137
5%
594
31%
594
14%
1529
April1st to 10thNight
25%
540
17%
1800
10%
540
35%
540
21%
1168
April11th to 20thNight
29%
533
19%
1775
12%
533
41%
533
19%
1181
April21st to endNight
32%
540
19%
1723
12%
540
44%
540
25%
1104
May1st to 10thNight
37%
540
16%
1558
10%
540
44%
540
23%
1067
May11th to 20thNight
37%
531
18%
1417
10%
531
44%
531
28%
967
May21st to endNight
43%
584
16%
1551
7%
582
49%
582
30%
1014
June1st to 10thNight
54%
540
18%
1440
8%
540
59%
540
38%
877
June11th to 20thNight
49%
540
18%
1440
8%
540
53%
540
35%
909
June21st to endNight
52%
540
20%
1440
10%
540
56%
540
38%
880
July1st to 10thNight
73%
525
17%
1400
10%
525
74%
525
43%
809
July11th to 20thNight
68%
522
23%
1392
13%
522
71%
522
47%
781
July21st to endNight
68%
591
24%
1569
18%
558
71%
558
45%
862
August1st to 10thNight
67%
537
22%
1601
20%
534
71%
534
38%
906
August11th to 20thNight
63%
534
25%
1600
25%
534
68%
534
38%
900
August21st to endNight
63%
594
24%
1970
25%
594
68%
594
36%
1053
September1st to 10thNight
56%
540
23%
1800
21%
540
62%
540
32%
1014
September11th to 20thNight
57%
540
30%
1800
27%
540
65%
540
36%
989
September21st to endNight
47%
638
25%
2054
16%
638
56%
638
37%
1108
October1st to 10thNight
42%
720
22%
2160
14%
720
49%
720
32%
1297
October11th to 20thNight
33%
720
22%
2160
11%
720
42%
720
25%
1372
October21st to endNight
32%
792
20%
2376
10%
792
41%
792
22%
1560
November1st to 10thNight
34%
740
25%
2406
14%
740
47%
740
29%
1394
November11th to 20thNight
25%
931
18%
2641
7%
931
34%
931
23%
1814
November21st to endNight
28%
950
17%
2660
8%
950
36%
950
24%
1791
December1st to 10thNight
23%
950
11%
2660
4%
950
30%
950
19%
1919
December11th to 20thNight
27%
948
13%
3177
6%
948
33%
948
15%
2261
December21st to endNight
19%
1037
9%
4831
5%
1026
29%
1026
7%
3888

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
13%9%47%6%35%5%5%7%36%
78297
Night
13%9%47%6%3445%7%39%
80728
TransparencyDay
47%5%13%22%12%1
78003
Night
46%5%12%23%13%2
80543
SeeingDay
16%10%29%27%14%4
14794
Night
16%9%32%32%11%1
24846

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
8%12%9%19%10%5%6%445%19%
2527
11th to 20thDay
10%12%5%10%10%7%6%6%7%5%23%
2658
21st to endDay
14%16%9%15%7%35%446%16%
3135
February1st to 10thDay
10%12%5%10%8%445%6%9%26%
1701
11th to 20thDay
13%11%5%6%7%46%5%5%6%33%
1574
21st to endDay
15%11%5%9%8%34347%30%
1458
March1st to 10thDay
14%11%6%8%5%35%45%6%32%
1916
11th to 20thDay
15%8%48%5%25%45%8%34%
1980
21st to endDay
20%12%47%6%345%5%7%27%
2218
April1st to 10thDay
20%11%46%5%345%47%31%
2160
11th to 20thDay
18%10%35%6%45%5%47%32%
2134
21st to endDay
22%9%35%6%3445%6%34%
2235
May1st to 10thDay
19%8%36%7%35%7%6%7%30%
2399
11th to 20thDay
19%9%35%5%3445%6%37%
2479
21st to endDay
16%6%36%5%35%5%5%8%37%
2725
June1st to 10thDay
11%5%25%5%345%6%9%43%
2520
11th to 20thDay
10%6%35%5%35%5%5%7%46%
2520
21st to endDay
11%6%36%6%35%6%7%10%37%
2520
July1st to 10thDay
9%4344346%6%10%47%
2520
11th to 20thDay
6%5%25%435%6%6%9%48%
2520
21st to endDay
7%424435%6%7%11%48%
2653
August1st to 10thDay
7%5%36%6%46%6%7%8%43%
2328
11th to 20thDay
11%5%25%5%35%5%6%8%44%
2301
21st to endDay
10%5%25%43445%9%49%
2386
September1st to 10thDay
13%425%334447%50%
2160
11th to 20thDay
10%5%25%435%45%7%50%
2160
21st to endDay
12%6%35%5%24447%47%
1885
October1st to 10thDay
15%6%35%5%3445%7%43%
1800
11th to 20thDay
19%8%345%3335%6%40%
1800
21st to endDay
17%9%35%43345%5%41%
1977
November1st to 10thDay
11%8%35%5%3445%7%45%
1672
11th to 20thDay
14%10%48%6%3446%7%34%
1535
21st to endDay
16%10%45%5%35%347%38%
1520
December1st to 10thDay
12%13%310%7%45%5%5%6%30%
1520
11th to 20thDay
13%12%5%8%7%35%45%7%31%
1918
21st to endDay
21%19%10%11%6%33335%18%
2783
January1st to 10thNight
9%13%8%18%7%44445%24%
4428
11th to 20thNight
11%15%6%10%8%35%6%7%6%23%
4312
21st to endNight
15%16%7%13%8%34446%21%
4532
February1st to 10thNight
9%12%5%11%8%35%5%46%32%
2464
11th to 20thNight
11%9%38%5%35%45%7%40%
2273
21st to endNight
15%8%5%7%7%44345%38%
1798
March1st to 10thNight
15%10%47%5%23446%41%
2059
11th to 20thNight
13%8%47%5%44448%39%
1980
21st to endNight
18%11%48%7%445%46%29%
2137
April1st to 10thNight
14%9%46%5%3345%6%40%
1800
11th to 20thNight
18%8%36%6%34446%38%
1775
21st to endNight
18%5%36%5%3345%7%42%
1723
May1st to 10thNight
17%6%36%5%36%5%5%6%39%
1558
11th to 20thNight
14%7%36%5%3446%8%40%
1416
21st to endNight
14%6%245%345%6%6%45%
1551
June1st to 10thNight
8%4245%346%8%10%47%
1440
11th to 20thNight
9%5%35%5%35%5%6%9%45%
1440
21st to endNight
10%5%344345%5%8%50%
1440
July1st to 10thNight
5%324445%5%6%8%55%
1440
11th to 20thNight
5%214425%5%49%58%
1440
21st to endNight
5%424425%45%10%56%
1661
August1st to 10thNight
6%425%5%25%6%7%9%51%
1611
11th to 20thNight
8%5%2343435%9%54%
1600
21st to endNight
9%42443345%7%57%
1970
September1st to 10thNight
10%5%25%424447%53%
1800
11th to 20thNight
12%5%25%323347%55%
1800
21st to endNight
9%5%2442335%6%56%
2054
October1st to 10thNight
13%6%34433446%51%
2160
11th to 20thNight
16%7%35%5%24446%45%
2160
21st to endNight
17%8%35%43445%6%40%
2376
November1st to 10thNight
11%6%35%433347%50%
2406
11th to 20thNight
13%10%47%6%25%45%6%39%
2641
21st to endNight
15%9%46%5%24445%42%
2660
December1st to 10thNight
11%10%49%7%45%5%6%6%32%
2660
11th to 20thNight
14%11%49%7%45%45%6%32%
3279
21st to endNight
21%16%6%12%6%34445%19%
4884

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
67%6%11%10%6%
2528
11th to 20thDay
61%411%16%7%
2658
21st to endDay
69%5%11%12%4
3135
February1st to 10thDay
55%5%14%17%8%1
1701
11th to 20thDay
51%5%12%22%8%1
1583
21st to endDay
56%411%19%9%2
1458
March1st to 10thDay
53%415%20%7%2
1916
11th to 20thDay
48%6%12%23%10%1
1980
21st to endDay
57%5%11%19%6%1
2218
April1st to 10thDay
54%5%11%22%8%1
2160
11th to 20thDay
52%5%11%20%11%1
2134
21st to endDay
52%5%10%21%11%2
2235
May1st to 10thDay
51%7%14%20%8%1
2399
11th to 20thDay
48%5%11%24%11%1
2483
21st to endDay
45%6%13%21%13%2
2725
June1st to 10thDay
36%7%16%25%15%2
2520
11th to 20thDay
36%7%12%23%19%2
2520
21st to endDay
41%8%13%23%14%1
2520
July1st to 10thDay
32%7%14%31%14%2
2451
11th to 20thDay
32%8%16%26%16%3
2445
21st to endDay
28%7%19%27%15%3
2506
August1st to 10thDay
36%8%14%29%12%2
2314
11th to 20thDay
37%6%12%29%14%1
2301
21st to endDay
34%5%11%28%20%2
2386
September1st to 10thDay
35%5%13%25%20%3
2160
11th to 20thDay
33%6%12%33%16%1
2160
21st to endDay
37%411%29%17%1
1885
October1st to 10thDay
40%5%11%26%16%1
1800
11th to 20thDay
45%311%24%16%1
1800
21st to endDay
46%412%23%13%1
1977
November1st to 10thDay
39%5%12%27%15%3
1672
11th to 20thDay
49%6%13%21%11%1
1535
21st to endDay
48%416%24%8%1
1520
December1st to 10thDay
55%5%12%18%8%2
1520
11th to 20thDay
54%418%15%9%1
1915
21st to endDay
72%49%11%4
2783
January1st to 10thNight
61%5%11%15%7%1
4428
11th to 20thNight
59%412%16%9%
4312
21st to endNight
66%410%14%5%1
4532
February1st to 10thNight
54%410%20%11%1
2464
11th to 20thNight
45%412%25%12%1
2274
21st to endNight
50%5%10%20%13%3
1798
March1st to 10thNight
46%412%27%10%1
2059
11th to 20thNight
45%5%13%22%15%1
1980
21st to endNight
55%5%13%17%8%1
2137
April1st to 10thNight
45%412%24%13%2
1800
11th to 20thNight
47%5%9%21%16%3
1775
21st to endNight
43%412%26%13%2
1723
May1st to 10thNight
45%6%12%21%15%1
1558
11th to 20thNight
43%5%12%25%12%2
1417
21st to endNight
38%6%13%24%16%3
1552
June1st to 10thNight
29%8%18%26%16%3
1440
11th to 20thNight
34%6%12%20%22%4
1440
21st to endNight
32%6%15%28%16%4
1440
July1st to 10thNight
26%7%14%32%18%3
1400
11th to 20thNight
23%6%17%33%17%5%
1392
21st to endNight
24%6%16%31%20%3
1569
August1st to 10thNight
27%7%15%32%16%3
1601
11th to 20thNight
29%5%14%32%17%2
1600
21st to endNight
28%6%12%26%23%6%
1970
September1st to 10thNight
33%5%10%26%24%2
1800
11th to 20thNight
31%410%35%19%1
1800
21st to endNight
30%311%31%22%2
2054
October1st to 10thNight
36%410%25%22%2
2160
11th to 20thNight
41%411%23%18%3
2160
21st to endNight
45%5%11%22%15%2
2376
November1st to 10thNight
36%413%26%18%3
2406
11th to 20thNight
47%412%24%12%1
2641
21st to endNight
45%413%26%10%1
2660
December1st to 10thNight
52%5%13%21%8%
2660
11th to 20thNight
52%5%14%23%6%1
3281
21st to endNight
68%5%8%13%5%
4884

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
19%12%35%24%9%1
270
11th to 20thDay
22%10%41%22%5%
270
21st to endDay
20%10%35%27%6%1
297
February1st to 10thDay
16%17%36%26%41
267
11th to 20thDay
20%20%34%16%11%
240
21st to endDay
22%14%38%22%4
198
March1st to 10thDay
15%16%45%18%5%2
240
11th to 20thDay
22%13%31%25%8%1
240
21st to endDay
33%14%28%19%5%1
304
April1st to 10thDay
26%15%35%18%5%1
420
11th to 20thDay
23%18%29%21%8%1
412
21st to endDay
24%14%32%19%9%2
495
May1st to 10thDay
25%12%29%23%9%2
603
11th to 20thDay
23%12%29%22%10%4
625
21st to endDay
17%8%27%26%17%4
679
June1st to 10thDay
9%6%25%33%23%4
630
11th to 20thDay
13%5%28%35%16%3
630
21st to endDay
10%8%33%30%14%5%
630
July1st to 10thDay
10%319%30%25%13%
621
11th to 20thDay
9%424%35%22%6%
618
21st to endDay
8%225%37%23%6%
684
August1st to 10thDay
8%323%32%26%8%
626
11th to 20thDay
12%5%17%32%25%9%
615
21st to endDay
11%322%35%22%6%
505
September1st to 10thDay
16%6%22%28%20%7%
450
11th to 20thDay
10%227%32%23%6%
450
21st to endDay
13%12%31%25%14%5%
291
October1st to 10thDay
20%7%30%22%17%4
270
11th to 20thDay
24%17%34%16%8%1
270
21st to endDay
24%17%31%18%7%3
297
November1st to 10thDay
17%12%39%21%7%3
270
11th to 20thDay
17%23%29%22%9%1
270
21st to endDay
24%14%36%19%7%
270
December1st to 10thDay
14%11%43%22%7%2
270
11th to 20thDay
16%13%34%26%10%1
270
21st to endDay
25%16%39%16%4
297
January1st to 10thNight
13%13%38%28%8%
950
11th to 20thNight
17%12%35%30%6%
950
21st to endNight
21%11%33%29%6%
1045
February1st to 10thNight
16%11%36%30%6%
948
11th to 20thNight
17%12%39%26%6%1
879
21st to endNight
18%13%38%25%5%1
614
March1st to 10thNight
21%13%32%26%8%1
619
11th to 20thNight
17%10%36%28%9%1
540
21st to endNight
24%8%38%23%6%1
594
April1st to 10thNight
18%13%41%24%3
540
11th to 20thNight
20%12%32%27%7%1
533
21st to endNight
21%8%34%28%8%1
540
May1st to 10thNight
20%7%33%31%9%1
540
11th to 20thNight
16%9%31%36%8%1
531
21st to endNight
17%5%28%33%15%1
584
June1st to 10thNight
9%428%43%16%1
540
11th to 20thNight
10%431%41%12%1
540
21st to endNight
13%426%41%16%1
540
July1st to 10thNight
6%113%46%31%3
525
11th to 20thNight
6%219%44%25%4
522
21st to endNight
5%118%50%23%2
591
August1st to 10thNight
6%216%47%28%1
537
11th to 20thNight
9%318%38%28%5%
534
21st to endNight
10%320%40%26%2
594
September1st to 10thNight
12%420%39%21%3
540
11th to 20thNight
14%322%38%21%3
540
21st to endNight
12%7%28%37%14%1
638
October1st to 10thNight
15%7%32%31%13%1
720
11th to 20thNight
20%10%32%30%8%
720
21st to endNight
22%12%29%29%7%1
792
November1st to 10thNight
15%9%37%31%7%1
740
11th to 20thNight
15%13%42%24%7%
931
21st to endNight
19%12%36%25%8%
950
December1st to 10thNight
16%12%40%25%6%1
950
11th to 20thNight
22%8%32%30%6%1
950
21st to endNight
25%12%33%24%6%
1045
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