Sioux City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sioux City clear sky chart from 2005-11-05 to 2017-09-22.

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
40%
16058
20%
46673
11%
16012
47%
16012
29%
29050

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
32%
900
17%
2339
7%
895
39%
895
26%
1580
January16th to endNight
26%
960
19%
2496
6%
960
36%
960
23%
1750
February1st to 15thNight
27%
880
11%
2288
3%
876
31%
876
21%
1662
February16th to endNight
31%
690
21%
1952
6%
690
42%
690
30%
1225
March1st to 15thNight
36%
576
19%
2016
13%
576
44%
576
24%
1231
March16th to endNight
28%
576
15%
2112
10%
576
36%
576
18%
1391
April1st to 15thNight
30%
539
17%
1839
12%
539
41%
539
22%
1153
April16th to endNight
32%
540
18%
1620
12%
540
42%
540
23%
1077
May1st to 15thNight
40%
540
19%
1620
12%
540
47%
540
30%
989
May16th to endNight
42%
562
16%
1583
7%
561
48%
561
30%
1000
June1st to 15thNight
50%
540
16%
1418
7%
540
52%
540
34%
891
June16th to endNight
57%
540
24%
1260
9%
540
61%
540
53%
742
July1st to 15thNight
65%
510
18%
1320
8%
510
68%
510
48%
732
July16th to endNight
76%
564
23%
1594
19%
531
77%
531
50%
783
August1st to 15thNight
66%
539
23%
1610
22%
536
70%
536
40%
888
August16th to endNight
61%
573
24%
1728
24%
573
67%
573
37%
976
September1st to 15thNight
57%
540
24%
1903
22%
540
66%
540
36%
986
September16th to endNight
48%
513
28%
1891
21%
513
60%
513
36%
932
October1st to 15thNight
37%
621
28%
1941
18%
621
47%
621
30%
1128
October16th to endNight
40%
720
22%
2128
12%
720
47%
720
31%
1285
November1st to 15thNight
39%
875
27%
2287
11%
875
49%
875
38%
1356
November16th to endNight
34%
900
21%
2520
10%
900
42%
900
30%
1582
December1st to 15thNight
28%
900
14%
2520
6%
900
35%
900
21%
1760
December16th to endNight
29%
960
17%
2688
8%
960
36%
960
19%
1951

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%35%42445%7%43%
48199
Night
10%6%24424446%47%
46855
Cloud CoverDay
12%6%25%42445%7%43%
48210
Night
10%6%25%424446%47%
46859
Cloud CoverDay
12%6%35%42445%7%42%
48208
Night
10%6%25%424446%47%
46859
TransparencyDay
40%6%14%24%12%1
47899
Night
36%5%13%26%15%2
46673
SeeingDay
14%6%29%30%15%2
6060
Night
13%8%32%33%10%
16059

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
7%8%47%6%5%6%446%37%
1596
16th to endDay
10%14%48%5%25%5%46%30%
1728
February1st to 15thDay
13%10%5%8%6%3445%6%32%
1575
16th to endDay
11%8%36%5%35%447%38%
1533
March1st to 15thDay
12%8%46%5%33346%40%
1933
16th to endDay
18%10%36%435%45%5%33%
2112
April1st to 15thDay
16%7%36%33435%6%39%
2106
16th to endDay
25%8%24423445%33%
2340
May1st to 15thDay
16%5%35%5%3445%7%39%
2331
16th to endDay
16%6%25%5%35%45%8%37%
2532
June1st to 15thDay
13%5%35%5%3445%6%41%
2538
16th to endDay
6%3144245%6%9%50%
2700
July1st to 15thDay
6%3243245%5%8%52%
2553
16th to endDay
5%2133245%6%9%53%
2466
August1st to 15thDay
9%425%5%346%5%8%44%
2340
16th to endDay
9%5%2442345%6%50%
2474
September1st to 15thDay
12%5%145%23436%49%
2055
16th to endDay
10%313323346%58%
1881
October1st to 15thDay
13%5%2342333452%
1678
16th to endDay
16%5%24323345%49%
1741
November1st to 15thDay
8%6%15%3235%5%6%53%
1571
16th to endDay
13%8%35%324348%42%
1440
December1st to 15thDay
13%9%6%9%5%2435%6%33%
1440
16th to endDay
13%11%5%8%7%45%447%26%
1536
January1st to 15thNight
6%7%37%7%345%5%7%40%
2339
16th to endNight
9%10%37%5%2436%8%37%
2496
February1st to 15thNight
12%11%47%5%34335%37%
2285
16th to endNight
7%7%24425%45%6%46%
1952
March1st to 15thNight
12%5%35%42345%6%46%
2004
16th to endNight
15%9%36%423447%38%
2112
April1st to 15thNight
15%5%25%425%445%44%
1839
16th to endNight
16%5%35%4345%36%41%
1620
May1st to 15thNight
14%413214448%48%
1620
16th to endNight
13%424423447%48%
1581
June1st to 15thNight
8%5%244235%5%9%46%
1418
16th to endNight
3223324347%62%
1260
July1st to 15thNight
5%21332435%8%59%
1401
16th to endNight
21242435%8%63%
1702
August1st to 15thNight
6%22423335%8%56%
1620
16th to endNight
8%313324447%54%
1728
September1st to 15thNight
9%313213346%58%
1903
16th to endNight
8%323222346%60%
1891
October1st to 15thNight
14%5%23323336%52%
1941
16th to endNight
14%5%2332234452%
2128
November1st to 15thNight
7%5%23323447%54%
2287
16th to endNight
10%6%24425%446%48%
2520
December1st to 15thNight
11%10%47%5%34446%38%
2520
16th to endNight
14%10%46%6%34446%33%
2688

Percentage Cloud Cover SW (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
7%8%47%7%46%347%36%
1596
16th to endDay
10%14%5%8%5%345%5%6%30%
1728
February1st to 15thDay
13%9%5%8%7%34346%32%
1575
16th to endDay
11%9%36%5%4445%6%38%
1533
March1st to 15thDay
12%9%46%433346%40%
1944
16th to endDay
18%9%46%42435%5%32%
2112
April1st to 15thDay
16%7%35%42435%6%38%
2106
16th to endDay
25%8%2443344433%
2340
May1st to 15thDay
16%6%25%5%3345%7%39%
2331
16th to endDay
16%6%25%4245%6%7%37%
2532
June1st to 15thDay
13%5%25%5%2445%7%41%
2538
16th to endDay
6%314325%5%5%9%50%
2700
July1st to 15thDay
7%31432445%8%52%
2553
16th to endDay
5%31243447%9%53%
2466
August1st to 15thDay
10%4145%35%5%5%8%44%
2340
16th to endDay
9%424424447%50%
2474
September1st to 15thDay
12%5%145%23436%49%
2055
16th to endDay
10%313313345%59%
1881
October1st to 15thDay
14%41442333452%
1678
16th to endDay
16%5%1432234449%
1741
November1st to 15thDay
8%5%2432345%6%52%
1571
16th to endDay
12%9%35%32435%7%42%
1440
December1st to 15thDay
13%10%5%9%5%3435%6%33%
1440
16th to endDay
14%11%5%9%7%45%447%26%
1536
January1st to 15thNight
7%7%36%7%35%5%5%7%40%
2339
16th to endNight
9%10%37%6%2435%8%38%
2496
February1st to 15thNight
13%11%47%5%24335%37%
2278
16th to endNight
8%7%3442445%6%47%
1952
March1st to 15thNight
12%6%35%32445%6%45%
2016
16th to endNight
15%8%35%424447%38%
2112
April1st to 15thNight
15%5%24424445%44%
1839
16th to endNight
16%5%35%5%33446%41%
1620
May1st to 15thNight
14%41331435%7%48%
1619
16th to endNight
13%424323447%48%
1581
June1st to 15thNight
9%425%4135%5%9%46%
1418
16th to endNight
423323447%62%
1260
July1st to 15thNight
5%21332335%8%60%
1401
16th to endNight
21232445%8%63%
1702
August1st to 15thNight
6%3134235%5%7%56%
1620
16th to endNight
9%322323447%55%
1728
September1st to 15thNight
9%313313346%58%
1903
16th to endNight
9%313213346%60%
1891
October1st to 15thNight
14%5%13313236%53%
1941
16th to endNight
14%5%1432333452%
2128
November1st to 15thNight
7%5%2432435%7%54%
2287
16th to endNight
9%6%24424347%48%
2520
December1st to 15thNight
12%10%47%5%34346%37%
2520
16th to endNight
15%10%46%5%34347%33%
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
7%8%47%8%46%446%36%
1596
16th to endDay
10%14%49%5%35%45%6%30%
1728
February1st to 15thDay
13%9%5%9%6%35%346%31%
1575
16th to endDay
11%9%36%5%35%446%38%
1533
March1st to 15thDay
12%9%46%433247%40%
1944
16th to endDay
18%9%45%5%3445%6%32%
2110
April1st to 15thDay
16%7%35%424446%39%
2106
16th to endDay
24%9%24433445%32%
2340
May1st to 15thDay
16%6%25%5%24447%39%
2331
16th to endDay
16%6%25%5%25%5%5%7%37%
2532
June1st to 15thDay
13%5%25%5%2445%7%41%
2538
16th to endDay
7%314425%5%5%9%50%
2700
July1st to 15thDay
7%31432445%8%52%
2553
16th to endDay
5%2133345%7%9%53%
2466
August1st to 15thDay
10%425%5%35%5%6%8%44%
2340
16th to endDay
10%42442445%7%50%
2474
September1st to 15thDay
12%5%24423436%49%
2055
16th to endDay
10%323312345%58%
1881
October1st to 15thDay
14%42442333452%
1678
16th to endDay
16%5%2431333449%
1741
November1st to 15thDay
8%6%2432345%7%52%
1571
16th to endDay
13%8%35%323348%42%
1440
December1st to 15thDay
13%9%5%9%5%3435%6%33%
1440
16th to endDay
13%12%5%9%6%45%447%26%
1536
January1st to 15thNight
7%7%36%7%35%5%5%7%40%
2339
16th to endNight
9%10%37%6%2435%8%37%
2496
February1st to 15thNight
13%10%47%5%24345%37%
2278
16th to endNight
8%7%34425%45%7%46%
1952
March1st to 15thNight
12%6%35%324446%45%
2016
16th to endNight
14%9%45%424447%38%
2112
April1st to 15thNight
15%5%245%25%445%44%
1839
16th to endNight
16%5%35%433446%41%
1620
May1st to 15thNight
14%42322335%8%48%
1619
16th to endNight
13%42442345%7%48%
1581
June1st to 15thNight
9%4344235%5%9%46%
1418
16th to endNight
4213323447%62%
1260
July1st to 15thNight
5%2232426%8%60%
1401
16th to endNight
21322445%8%63%
1702
August1st to 15thNight
6%2243235%5%7%56%
1620
16th to endNight
9%313323447%55%
1728
September1st to 15thNight
10%213323346%58%
1903
16th to endNight
8%313213346%60%
1891
October1st to 15thNight
14%423314236%52%
1941
16th to endNight
15%5%2432333452%
2128
November1st to 15thNight
7%5%24324347%54%
2287
16th to endNight
9%7%25%424346%48%
2520
December1st to 15thNight
12%10%47%5%24446%37%
2520
16th to endNight
15%10%47%5%33446%33%
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
46%6%16%20%9%
1597
16th to endDay
51%6%15%18%7%
1728
February1st to 15thDay
52%5%15%18%7%
1576
16th to endDay
44%8%14%20%10%1
1533
March1st to 15thDay
44%5%15%22%10%1
1944
16th to endDay
52%5%13%21%5%
2112
April1st to 15thDay
45%5%13%24%9%
2106
16th to endDay
53%5%10%20%9%
2340
May1st to 15thDay
44%6%14%22%11%
2331
16th to endDay
45%7%13%22%9%
2536
June1st to 15thDay
40%7%14%23%12%1
2538
16th to endDay
28%7%15%30%13%4
2700
July1st to 15thDay
30%8%16%28%12%3
2405
16th to endDay
23%7%16%31%17%3
2311
August1st to 15thDay
35%7%14%27%13%1
2326
16th to endDay
32%6%11%26%17%4
2474
September1st to 15thDay
35%6%10%28%17%1
2055
16th to endDay
28%413%33%18%1
1881
October1st to 15thDay
35%410%27%19%2
1678
16th to endDay
37%412%27%15%2
1741
November1st to 15thDay
31%5%16%25%20%
1571
16th to endDay
41%5%17%25%10%
1440
December1st to 15thDay
51%5%14%19%6%1
1440
16th to endDay
57%5%12%16%6%1
1536
January1st to 15thNight
40%6%16%24%11%
2339
16th to endNight
44%7%16%22%8%
2496
February1st to 15thNight
50%5%13%22%8%1
2288
16th to endNight
35%6%16%25%12%2
1952
March1st to 15thNight
38%6%13%27%11%1
2016
16th to endNight
46%6%13%23%7%1
2112
April1st to 15thNight
40%6%10%26%14%1
1839
16th to endNight
44%5%13%22%12%1
1620
May1st to 15thNight
34%7%12%26%19%1
1620
16th to endNight
36%6%16%24%14%1
1583
June1st to 15thNight
33%7%14%27%14%2
1418
16th to endNight
21%5%14%31%22%4
1260
July1st to 15thNight
22%6%16%29%19%6%
1320
16th to endNight
18%5%15%32%22%4
1594
August1st to 15thNight
26%6%14%30%20%2
1610
16th to endNight
28%5%12%26%19%6%
1728
September1st to 15thNight
26%5%10%31%21%4
1903
16th to endNight
25%411%35%19%3
1891
October1st to 15thNight
33%48%27%22%3
1941
16th to endNight
36%314%26%17%1
2128
November1st to 15thNight
29%413%24%24%3
2287
16th to endNight
36%5%15%27%13%
2520
December1st to 15thNight
48%416%23%7%
2520
16th to endNight
50%6%12%19%9%
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
15%11%36%28%7%
90
16th to endDay
25%139%29%41
96
February1st to 15thDay
18%11%43%22%4
90
16th to endDay
13%12%35%25%11%1
81
March1st to 15thDay
14%12%51%17%4
90
16th to endDay
33%7%29%20%9%
96
April1st to 15thDay
17%11%38%25%7%
225
16th to endDay
32%10%28%19%7%2
450
May1st to 15thDay
20%9%31%24%11%1
468
16th to endDay
19%7%32%24%12%3
517
June1st to 15thDay
13%6%27%34%16%2
495
16th to endDay
5%6%35%34%15%2
495
July1st to 15thDay
9%322%38%21%4
475
16th to endDay
4122%44%25%1
515
August1st to 15thDay
10%220%34%29%3
493
16th to endDay
10%323%34%22%5%
514
September1st to 15thDay
13%329%31%16%5%
210
16th to endDay
12%433%27%17%4
108
October1st to 15thDay
5%12%32%35%10%4
90
16th to endDay
11%6%40%32%9%
96
November1st to 15thDay
5%7%31%40%11%4
90
16th to endDay
42%7%24%16%8%
90
December1st to 15thDay
23%21%32%14%5%3
90
16th to endDay
23%19%37%14%4
96
January1st to 15thNight
11%11%37%30%7%
900
16th to endNight
15%11%38%27%6%
960
February1st to 15thNight
18%11%37%26%6%
880
16th to endNight
11%9%43%26%9%
690
March1st to 15thNight
14%7%36%33%7%
576
16th to endNight
19%10%35%28%5%
576
April1st to 15thNight
18%11%36%29%3
539
16th to endNight
19%10%33%27%8%
540
May1st to 15thNight
16%8%31%31%11%
540
16th to endNight
15%432%35%9%
563
June1st to 15thNight
11%5%26%44%12%
540
16th to endNight
4230%48%14%
540
July1st to 15thNight
6%220%42%26%
510
16th to endNight
215%58%21%1
564
August1st to 15thNight
5%218%48%22%1
539
16th to endNight
10%222%39%22%2
573
September1st to 15thNight
10%424%37%20%2
540
16th to endNight
10%6%32%32%15%2
513
October1st to 15thNight
17%9%32%29%10%1
621
16th to endNight
18%7%28%33%11%
720
November1st to 15thNight
10%11%35%32%8%1
875
16th to endNight
14%11%38%27%8%
900
December1st to 15thNight
18%10%34%29%5%
900
16th to endNight
20%8%33%29%6%
960
Page generated at 2017-09-23 05:43:35. Version ac04

Copyright 2017 A. Danko


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