Storm Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Storm Lake clear sky chart from 2005-11-05 to 2017-09-18.

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%
16049
19%
46931
10%
16003
45%
16003
28%
29697

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
28%
900
16%
2404
7%
895
36%
895
25%
1626
January16th to endNight
24%
960
18%
2496
5%
960
33%
960
21%
1786
February1st to 15thNight
23%
880
11%
2288
2%
876
29%
876
20%
1680
February16th to endNight
28%
735
20%
1997
6%
735
38%
735
27%
1323
March1st to 15thNight
36%
541
19%
1981
14%
541
46%
541
23%
1200
March16th to endNight
26%
576
14%
2112
11%
576
34%
576
16%
1452
April1st to 15thNight
28%
539
17%
1845
11%
539
39%
539
23%
1151
April16th to endNight
29%
540
17%
1629
10%
540
40%
540
21%
1137
May1st to 15thNight
39%
540
18%
1620
12%
540
46%
540
28%
1025
May16th to endNight
43%
562
16%
1514
7%
561
48%
561
29%
983
June1st to 15thNight
49%
540
15%
1440
6%
540
52%
540
32%
927
June16th to endNight
58%
540
20%
1440
8%
540
62%
540
46%
801
July1st to 15thNight
67%
510
18%
1367
7%
510
70%
510
50%
745
July16th to endNight
74%
564
23%
1594
19%
531
75%
531
53%
771
August1st to 15thNight
66%
539
22%
1610
21%
536
70%
536
40%
892
August16th to endNight
61%
573
23%
1761
23%
573
66%
573
36%
996
September1st to 15thNight
58%
540
24%
1848
22%
540
67%
540
37%
969
September16th to endNight
48%
501
26%
1848
20%
501
60%
501
33%
969
October1st to 15thNight
38%
652
27%
1972
16%
652
47%
652
32%
1137
October16th to endNight
36%
704
21%
2112
11%
704
43%
704
27%
1287
November1st to 15thNight
36%
853
25%
2325
12%
853
46%
853
33%
1410
November16th to endNight
28%
900
18%
2520
9%
900
36%
900
27%
1643
December1st to 15thNight
24%
900
13%
2520
4%
900
32%
900
20%
1789
December16th to endNight
22%
960
16%
2688
6%
960
31%
960
17%
1998

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%7%35%5%3445%7%40%
47859
Night
11%6%35%42435%7%45%
47112
Cloud CoverDay
13%7%35%5%3445%7%40%
47870
Night
11%6%35%424447%45%
47116
Cloud CoverDay
13%7%35%5%3445%7%40%
47868
Night
10%6%35%42445%7%45%
47116
TransparencyDay
42%5%14%23%11%1
47558
Night
38%5%14%24%14%1
46931
SeeingDay
15%7%28%30%14%3
6056
Night
14%8%33%32%11%
16050

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%11%48%7%45%35%6%34%
1532
16th to endDay
11%10%5%10%6%345%5%7%28%
1728
February1st to 15thDay
12%12%5%8%7%4345%6%30%
1575
16th to endDay
13%8%37%6%35%446%35%
1485
March1st to 15thDay
13%10%5%8%424346%36%
1966
16th to endDay
19%10%46%5%24446%30%
2112
April1st to 15thDay
15%8%36%5%3435%7%37%
2103
16th to endDay
27%7%345%23346%31%
2330
May1st to 15thDay
19%7%36%42346%7%34%
2331
16th to endDay
16%6%25%5%3445%7%39%
2601
June1st to 15thDay
15%6%244445%5%7%39%
2520
16th to endDay
7%313435%46%9%48%
2520
July1st to 15thDay
7%3144245%5%9%49%
2511
16th to endDay
6%3145%25%5%6%9%50%
2466
August1st to 15thDay
10%5%245%2446%8%44%
2340
16th to endDay
11%5%25%43445%7%46%
2441
September1st to 15thDay
11%41432445%6%50%
2109
16th to endDay
12%213323446%54%
1834
October1st to 15thDay
14%5%24423335%50%
1650
16th to endDay
15%7%34323345%46%
1760
November1st to 15thDay
9%5%2442445%6%48%
1529
16th to endDay
14%8%35%5%23448%39%
1440
December1st to 15thDay
14%10%49%7%345%46%29%
1440
16th to endDay
13%12%6%8%7%445%5%5%25%
1536
January1st to 15thNight
8%7%37%6%35%5%5%7%37%
2404
16th to endNight
11%9%5%6%7%345%5%6%34%
2496
February1st to 15thNight
12%10%6%8%5%33345%35%
2285
16th to endNight
9%7%46%425%45%7%43%
1997
March1st to 15thNight
13%6%25%33435%8%43%
1969
16th to endNight
14%10%47%5%34346%36%
2112
April1st to 15thNight
14%6%245%3445%6%42%
1845
16th to endNight
18%8%36%424346%37%
1629
May1st to 15thNight
14%5%24333347%46%
1620
16th to endNight
12%5%245%3435%9%42%
1512
June1st to 15thNight
8%435%5%35%45%8%45%
1440
16th to endNight
4223425%45%9%58%
1440
July1st to 15thNight
321232446%8%60%
1447
16th to endNight
311231337%10%60%
1702
August1st to 15thNight
5%22442445%8%56%
1620
16th to endNight
8%4245%33246%56%
1761
September1st to 15thNight
9%223323346%58%
1848
16th to endNight
9%424323346%55%
1848
October1st to 15thNight
12%5%23322245%54%
1972
16th to endNight
14%7%15%322336%49%
2112
November1st to 15thNight
9%5%24424437%51%
2325
16th to endNight
12%7%26%42345%6%44%
2520
December1st to 15thNight
12%12%46%5%25%446%35%
2520
16th to endNight
16%10%5%7%7%24346%31%
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%11%48%8%45%45%6%34%
1532
16th to endDay
11%11%5%10%6%3445%7%28%
1728
February1st to 15thDay
11%12%5%9%6%4445%6%29%
1575
16th to endDay
13%9%37%5%36%446%35%
1485
March1st to 15thDay
13%10%48%5%33345%36%
1977
16th to endDay
19%11%46%5%24446%30%
2112
April1st to 15thDay
15%8%35%5%3435%7%36%
2103
16th to endDay
27%7%35%423346%31%
2330
May1st to 15thDay
18%7%35%5%2446%7%34%
2331
16th to endDay
16%6%35%6%24447%39%
2601
June1st to 15thDay
15%6%24435%5%5%8%38%
2520
16th to endDay
7%31443446%10%48%
2520
July1st to 15thDay
7%3144245%5%9%49%
2511
16th to endDay
5%314435%46%9%50%
2466
August1st to 15thDay
10%5%25%42447%8%43%
2340
16th to endDay
10%5%24434447%47%
2441
September1st to 15thDay
11%41432445%6%50%
2109
16th to endDay
12%213323346%55%
1834
October1st to 15thDay
14%5%24323335%50%
1650
16th to endDay
15%7%24324345%46%
1760
November1st to 15thDay
9%6%2442445%6%48%
1529
16th to endDay
13%8%35%5%24348%39%
1440
December1st to 15thDay
15%9%49%7%35%445%29%
1440
16th to endDay
13%12%7%8%7%445%45%25%
1536
January1st to 15thNight
8%7%37%6%35%5%5%8%37%
2404
16th to endNight
11%9%47%6%345%5%7%35%
2496
February1st to 15thNight
12%11%5%8%6%33445%35%
2278
16th to endNight
9%7%36%42445%7%43%
1997
March1st to 15thNight
13%6%25%42435%8%43%
1981
16th to endNight
14%11%47%5%24336%35%
2112
April1st to 15thNight
14%7%1442445%6%42%
1845
16th to endNight
18%8%36%5%23345%37%
1629
May1st to 15thNight
14%5%24423348%46%
1619
16th to endNight
12%5%245%2436%9%42%
1512
June1st to 15thNight
8%5%245%34449%45%
1440
16th to endNight
3223325%45%9%57%
1440
July1st to 15thNight
321232446%8%60%
1447
16th to endNight
311231337%10%60%
1702
August1st to 15thNight
5%21443345%8%55%
1620
16th to endNight
8%414423346%55%
1761
September1st to 15thNight
9%31331335%6%58%
1848
16th to endNight
9%414323346%55%
1848
October1st to 15thNight
12%6%13322335%53%
1972
16th to endNight
14%7%25%322335%50%
2112
November1st to 15thNight
9%5%24324437%51%
2325
16th to endNight
12%7%26%42345%6%44%
2520
December1st to 15thNight
12%12%47%425%446%35%
2520
16th to endNight
16%10%5%8%7%24346%30%
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%11%48%7%45%446%34%
1532
16th to endDay
11%10%6%10%6%345%47%29%
1728
February1st to 15thDay
11%12%49%7%4445%6%30%
1575
16th to endDay
12%8%38%5%35%45%6%35%
1485
March1st to 15thDay
12%11%48%5%24345%36%
1977
16th to endDay
19%11%36%5%24346%30%
2110
April1st to 15thDay
15%8%36%43435%8%36%
2103
16th to endDay
26%8%35%423346%31%
2330
May1st to 15thDay
18%7%35%43446%7%34%
2331
16th to endDay
16%6%25%6%24347%39%
2601
June1st to 15thDay
15%5%244445%5%8%38%
2520
16th to endDay
7%314425%46%9%48%
2520
July1st to 15thDay
7%3144245%6%9%49%
2511
16th to endDay
5%314435%5%6%9%50%
2466
August1st to 15thDay
10%5%25%435%47%8%43%
2340
16th to endDay
10%5%25%424447%47%
2441
September1st to 15thDay
12%41433445%6%49%
2109
16th to endDay
11%313323446%55%
1834
October1st to 15thDay
14%5%24423335%50%
1650
16th to endDay
15%7%25%324345%45%
1760
November1st to 15thDay
9%6%34424447%48%
1529
16th to endDay
14%8%35%5%2345%7%39%
1440
December1st to 15thDay
15%9%5%8%8%345%45%29%
1440
16th to endDay
14%12%6%9%6%45%45%5%25%
1536
January1st to 15thNight
8%7%36%7%35%5%5%8%37%
2404
16th to endNight
11%9%5%7%6%3445%6%35%
2496
February1st to 15thNight
11%11%6%8%5%33345%35%
2278
16th to endNight
8%8%37%425%45%7%43%
1997
March1st to 15thNight
13%6%2442435%8%43%
1981
16th to endNight
14%10%5%7%5%34346%35%
2112
April1st to 15thNight
14%7%2442435%6%42%
1845
16th to endNight
18%8%36%5%23345%37%
1629
May1st to 15thNight
14%5%14432347%46%
1619
16th to endNight
12%6%2443436%9%42%
1512
June1st to 15thNight
8%5%25%5%25%45%8%45%
1440
16th to endNight
42134245%5%9%57%
1440
July1st to 15thNight
321232445%10%60%
1447
16th to endNight
311222337%10%60%
1702
August1st to 15thNight
5%215%425%35%7%56%
1620
16th to endNight
8%414423346%56%
1761
September1st to 15thNight
9%32332335%6%57%
1848
16th to endNight
9%414323346%55%
1848
October1st to 15thNight
12%5%14323345%54%
1972
16th to endNight
14%6%24322335%49%
2112
November1st to 15thNight
8%6%24424437%51%
2325
16th to endNight
11%7%36%42345%6%44%
2520
December1st to 15thNight
12%12%46%5%24446%35%
2520
16th to endNight
16%10%48%7%24345%31%
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
49%5%14%20%9%
1533
16th to endDay
54%5%15%19%5%
1728
February1st to 15thDay
55%413%18%8%
1576
16th to endDay
49%5%14%20%9%1
1485
March1st to 15thDay
48%5%14%21%9%
1977
16th to endDay
54%6%14%18%6%
2112
April1st to 15thDay
47%414%24%8%1
2103
16th to endDay
54%5%10%20%7%
2330
May1st to 15thDay
47%5%14%22%9%
2331
16th to endDay
44%6%13%21%12%
2605
June1st to 15thDay
42%7%14%23%11%1
2520
16th to endDay
30%7%16%29%12%3
2520
July1st to 15thDay
31%8%16%28%12%4
2362
16th to endDay
28%7%15%28%17%2
2311
August1st to 15thDay
36%7%15%26%12%1
2326
16th to endDay
36%6%11%26%15%3
2441
September1st to 15thDay
33%5%12%28%17%1
2109
16th to endDay
30%415%30%18%
1834
October1st to 15thDay
36%411%26%19%1
1650
16th to endDay
40%413%26%14%1
1760
November1st to 15thDay
34%414%25%20%
1529
16th to endDay
44%417%22%10%
1440
December1st to 15thDay
55%6%14%15%6%1
1440
16th to endDay
60%412%15%5%1
1536
January1st to 15thNight
43%5%16%21%13%
2404
16th to endNight
47%5%15%21%8%
2496
February1st to 15thNight
52%412%21%8%1
2288
16th to endNight
40%5%14%23%13%2
1997
March1st to 15thNight
39%5%13%27%12%1
1981
16th to endNight
50%5%12%21%8%1
2112
April1st to 15thNight
41%412%25%14%1
1845
16th to endNight
48%5%12%19%11%2
1629
May1st to 15thNight
37%6%13%25%16%1
1620
16th to endNight
37%6%17%22%13%1
1514
June1st to 15thNight
36%6%16%25%12%2
1440
16th to endNight
23%6%15%29%21%4
1440
July1st to 15thNight
20%6%18%31%17%4
1367
16th to endNight
17%5%19%33%20%3
1594
August1st to 15thNight
26%6%14%30%19%2
1610
16th to endNight
29%5%13%26%18%5%
1761
September1st to 15thNight
26%5%12%29%22%3
1848
16th to endNight
29%410%32%20%2
1848
October1st to 15thNight
33%411%25%21%3
1972
16th to endNight
37%414%25%16%1
2112
November1st to 15thNight
33%413%23%23%2
2325
16th to endNight
39%5%16%24%12%1
2520
December1st to 15thNight
50%415%22%7%
2520
16th to endNight
55%412%17%9%1
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
14%12%36%28%6%1
90
16th to endDay
25%6%39%21%43
96
February1st to 15thDay
13%21%43%18%3
90
16th to endDay
19%14%28%24%11%1
81
March1st to 15thDay
20%14%42%16%6%
90
16th to endDay
37%5%27%23%6%
96
April1st to 15thDay
17%11%35%28%7%
222
16th to endDay
32%12%28%16%8%2
440
May1st to 15thDay
23%11%28%25%9%1
468
16th to endDay
17%6%35%24%12%3
517
June1st to 15thDay
14%7%25%34%15%2
495
16th to endDay
7%5%33%35%14%3
495
July1st to 15thDay
8%226%34%21%6%
475
16th to endDay
5%221%43%21%4
515
August1st to 15thDay
10%219%38%25%4
493
16th to endDay
10%421%33%21%7%
481
September1st to 15thDay
9%427%36%15%7%
264
16th to endDay
8%9%25%31%25%1
96
October1st to 15thDay
10%6%32%36%12%2
90
16th to endDay
15%442%28%9%
96
November1st to 15thDay
27%33%38%13%4
90
16th to endDay
37%7%33%20%1
90
December1st to 15thDay
21%20%37%15%41
90
16th to endDay
30%17%38%12%1
96
January1st to 15thNight
11%12%39%27%7%1
900
16th to endNight
16%10%40%27%4
960
February1st to 15thNight
17%10%39%25%5%
880
16th to endNight
11%10%42%25%8%1
735
March1st to 15thNight
15%8%35%28%9%
541
16th to endNight
18%11%37%23%8%
576
April1st to 15thNight
19%10%36%28%4
539
16th to endNight
22%9%33%24%8%
540
May1st to 15thNight
15%10%31%32%9%
540
16th to endNight
14%7%30%36%10%
563
June1st to 15thNight
11%428%42%12%
540
16th to endNight
4328%49%13%
540
July1st to 15thNight
4123%44%24%1
510
16th to endNight
4116%53%23%1
564
August1st to 15thNight
6%117%45%26%1
539
16th to endNight
9%218%41%22%5%
573
September1st to 15thNight
10%124%37%21%3
540
16th to endNight
10%5%31%33%17%1
501
October1st to 15thNight
14%8%34%29%11%1
652
16th to endNight
19%9%30%31%8%
704
November1st to 15thNight
12%12%35%29%9%
853
16th to endNight
15%11%39%24%8%
900
December1st to 15thNight
18%10%39%26%4
900
16th to endNight
20%10%35%25%7%
960
Page generated at 2017-09-19 06:32:23. Version ac04

Copyright 2017 A. Danko


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