Wartburg College Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wartburg College Observatory clear sky chart from 2005-11-05 to 2017-12-04.

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%
16369
18%
47864
10%
16322
45%
16322
25%
31429

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
30%
900
13%
2506
6%
895
36%
895
21%
1779
January16th to endNight
24%
960
14%
2511
5%
960
31%
960
19%
1862
February1st to 15thNight
24%
879
12%
2288
3%
875
30%
875
20%
1684
February16th to endNight
32%
708
19%
1970
7%
708
41%
708
24%
1312
March1st to 15thNight
33%
594
19%
2034
13%
594
42%
594
23%
1268
March16th to endNight
27%
576
11%
2084
7%
576
34%
576
15%
1470
April1st to 15thNight
28%
539
16%
1797
11%
539
37%
539
21%
1182
April16th to endNight
34%
540
19%
1743
14%
540
46%
540
23%
1164
May1st to 15thNight
38%
540
16%
1515
10%
540
44%
540
25%
1056
May16th to endNight
42%
563
16%
1498
6%
561
49%
561
30%
983
June1st to 15thNight
51%
540
13%
1440
6%
540
53%
540
32%
925
June16th to endNight
52%
540
19%
1440
8%
540
56%
540
37%
888
July1st to 15thNight
68%
510
16%
1360
8%
510
70%
510
45%
772
July16th to endNight
72%
564
23%
1466
17%
531
73%
531
45%
819
August1st to 15thNight
66%
539
22%
1610
21%
536
70%
536
39%
902
August16th to endNight
61%
573
21%
1842
23%
573
65%
573
34%
1053
September1st to 15thNight
61%
540
27%
1800
26%
540
67%
540
36%
969
September16th to endNight
53%
602
26%
1970
19%
602
61%
602
36%
1087
October1st to 15thNight
39%
720
23%
2160
14%
720
46%
720
30%
1327
October16th to endNight
36%
768
21%
2307
12%
768
43%
768
25%
1480
November1st to 15thNight
33%
819
22%
2530
13%
819
43%
819
27%
1562
November16th to endNight
26%
975
17%
2730
7%
975
35%
975
25%
1826
December1st to 15thNight
22%
920
10%
2575
3%
920
29%
920
17%
1935
December16th to endNight
22%
960
12%
2688
4%
960
29%
960
13%
2124

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%37%
48633
Night
13%7%35%424446%42%
48037
Cloud CoverDay
26%6%25%423446%32%
48644
Night
25%6%25%423345%36%
48041
Cloud CoverDay
14%7%36%5%3445%7%37%
48642
Night
13%7%35%424446%42%
48041
TransparencyDay
45%6%13%22%10%1
48324
Night
42%5%13%23%13%1
47864
SeeingDay
16%7%28%27%16%4
6290
Night
16%7%31%31%12%1
16370

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
9%11%6%9%7%45%5%37%28%
1432
16th to endDay
14%13%5%10%6%35%5%5%6%22%
1710
February1st to 15thDay
11%12%6%7%6%345%36%30%
1575
16th to endDay
14%9%46%5%35%45%6%33%
1503
March1st to 15thDay
15%9%37%42435%8%34%
1927
16th to endDay
18%11%37%5%34346%30%
2139
April1st to 15thDay
19%9%35%5%33447%32%
2151
16th to endDay
24%9%26%5%23445%30%
2215
May1st to 15thDay
21%7%245%345%5%8%30%
2435
16th to endDay
16%6%35%5%35%447%38%
2617
June1st to 15thDay
15%5%25%4245%5%8%39%
2520
16th to endDay
10%425%5%25%5%5%8%43%
2520
July1st to 15thDay
7%5%144345%5%9%48%
2520
16th to endDay
7%4245%25%6%7%9%44%
2602
August1st to 15thDay
9%4245%35%5%7%8%43%
2340
16th to endDay
12%5%25%4345%5%8%41%
2360
September1st to 15thDay
11%42432335%8%51%
2160
16th to endDay
13%5%2442445%6%45%
1974
October1st to 15thDay
18%6%145%23346%43%
1800
16th to endDay
17%7%25%413346%42%
1915
November1st to 15thDay
12%7%3442435%5%45%
1655
16th to endDay
16%8%26%423446%39%
1560
December1st to 15thDay
16%12%5%9%6%35%5%36%25%
1467
16th to endDay
20%14%6%7%7%25%42423%
1536
January1st to 15thNight
10%9%5%7%5%35%5%5%7%33%
2506
16th to endNight
12%10%5%10%6%34347%31%
2511
February1st to 15thNight
10%10%5%8%6%3445%5%33%
2285
16th to endNight
12%6%36%5%34347%42%
1970
March1st to 15thNight
14%8%34323346%44%
2022
16th to endNight
16%10%47%5%3445%6%31%
2084
April1st to 15thNight
15%8%36%5%23446%39%
1797
16th to endNight
22%6%24423345%40%
1743
May1st to 15thNight
16%6%24425%5%6%6%39%
1515
16th to endNight
11%5%25%4245%5%6%45%
1496
June1st to 15thNight
10%4145%25%6%6%9%42%
1440
16th to endNight
8%4145%2445%9%50%
1440
July1st to 15thNight
43123245%49%57%
1440
16th to endNight
421341446%10%56%
1566
August1st to 15thNight
6%3144245%6%8%52%
1620
16th to endNight
11%414322447%53%
1842
September1st to 15thNight
10%314313345%58%
1800
16th to endNight
9%413324347%54%
1970
October1st to 15thNight
15%425%423346%48%
2160
16th to endNight
15%7%25%323446%43%
2307
November1st to 15thNight
13%7%26%423345%47%
2530
16th to endNight
15%8%35%41335%5%42%
2730
December1st to 15thNight
16%11%47%6%35%445%29%
2575
16th to endNight
20%13%5%7%6%34345%25%
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
22%8%48%6%45%436%24%
1432
16th to endDay
28%11%39%5%34445%18%
1710
February1st to 15thDay
25%10%5%7%5%33325%25%
1575
16th to endDay
26%8%26%5%34345%28%
1503
March1st to 15thDay
28%7%26%423247%30%
1938
16th to endDay
29%9%36%433345%25%
2139
April1st to 15thDay
32%7%25%5%33346%27%
2151
16th to endDay
36%8%25%5%2333423%
2215
May1st to 15thDay
33%6%245%23446%26%
2435
16th to endDay
31%5%25%423335%30%
2617
June1st to 15thDay
29%5%25%423446%31%
2520
16th to endDay
24%415%424346%37%
2520
July1st to 15thDay
23%41343345%7%39%
2520
16th to endDay
23%3144245%6%8%34%
2602
August1st to 15thDay
16%424435%5%6%7%40%
2340
16th to endDay
18%5%2443445%7%39%
2360
September1st to 15thDay
17%414313347%48%
2160
16th to endDay
20%5%24323446%42%
1974
October1st to 15thDay
25%5%135%23336%40%
1800
16th to endDay
23%6%24412335%39%
1915
November1st to 15thDay
23%6%14423345%40%
1655
16th to endDay
28%7%25%323245%35%
1560
December1st to 15thDay
30%11%48%5%2342421%
1467
16th to endDay
32%13%47%6%3332320%
1536
January1st to 15thNight
23%8%36%5%34446%30%
2506
16th to endNight
26%8%39%5%23336%26%
2511
February1st to 15thNight
24%10%47%5%2334429%
2278
16th to endNight
25%5%25%5%23346%35%
1970
March1st to 15thNight
28%7%24312235%36%
2034
16th to endNight
28%9%36%5%33345%27%
2084
April1st to 15thNight
29%6%25%423335%33%
1797
16th to endNight
35%5%2432233432%
1743
May1st to 15thNight
29%5%2332445%5%33%
1514
16th to endNight
26%5%25%322446%36%
1496
June1st to 15thNight
26%4144245%5%8%33%
1440
16th to endNight
23%314324447%42%
1440
July1st to 15thNight
20%312323447%46%
1440
16th to endNight
19%21231345%8%47%
1566
August1st to 15thNight
14%31332346%8%49%
1620
16th to endNight
18%313312336%50%
1842
September1st to 15thNight
17%313312235%53%
1800
16th to endNight
16%413323337%51%
1970
October1st to 15thNight
22%414423335%44%
2160
16th to endNight
22%6%24323345%41%
2307
November1st to 15thNight
23%6%15%32223442%
2530
16th to endNight
26%7%2431234439%
2730
December1st to 15thNight
30%9%36%5%23445%23%
2575
16th to endNight
34%11%37%5%2233421%
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
9%11%6%9%7%45%447%28%
1432
16th to endDay
14%13%5%10%6%36%5%5%6%22%
1710
February1st to 15thDay
11%12%6%7%6%35%5%36%30%
1575
16th to endDay
14%9%37%5%35%45%6%33%
1503
March1st to 15thDay
15%8%47%42435%8%34%
1938
16th to endDay
18%11%46%5%34447%29%
2137
April1st to 15thDay
19%9%36%5%3435%7%32%
2151
16th to endDay
24%9%36%5%23445%30%
2215
May1st to 15thDay
20%7%35%5%2445%8%30%
2435
16th to endDay
15%6%35%5%35%447%37%
2617
June1st to 15thDay
15%5%35%4245%5%8%39%
2520
16th to endDay
10%426%5%35%5%5%8%42%
2520
July1st to 15thDay
7%42443446%9%47%
2520
16th to endDay
6%4245%35%6%7%10%43%
2602
August1st to 15thDay
8%5%24435%6%7%8%42%
2340
16th to endDay
12%5%25%5%345%5%8%41%
2360
September1st to 15thDay
11%42441345%8%51%
2160
16th to endDay
13%5%2443445%6%45%
1974
October1st to 15thDay
18%5%25%423346%43%
1800
16th to endDay
17%7%25%413346%42%
1915
November1st to 15thDay
11%7%35%434446%45%
1655
16th to endDay
16%8%35%42435%6%39%
1560
December1st to 15thDay
16%13%410%6%345%45%25%
1467
16th to endDay
19%14%6%8%6%3442423%
1536
January1st to 15thNight
10%9%5%7%5%35%5%5%7%33%
2506
16th to endNight
11%10%5%10%6%34447%31%
2511
February1st to 15thNight
10%11%5%8%7%25%45%5%33%
2278
16th to endNight
12%6%36%6%24347%42%
1970
March1st to 15thNight
15%8%34323336%44%
2034
16th to endNight
16%9%47%5%245%5%6%31%
2084
April1st to 15thNight
15%8%36%5%24446%39%
1797
16th to endNight
22%5%25%323335%39%
1743
May1st to 15thNight
16%6%24425%5%6%7%38%
1514
16th to endNight
11%5%35%4245%5%7%44%
1496
June1st to 15thNight
11%424435%6%6%9%42%
1440
16th to endNight
8%42442445%8%50%
1440
July1st to 15thNight
44123245%48%57%
1440
16th to endNight
321332347%10%56%
1566
August1st to 15thNight
5%3144245%6%9%52%
1620
16th to endNight
11%424312347%52%
1842
September1st to 15thNight
11%314312346%58%
1800
16th to endNight
9%413323347%54%
1970
October1st to 15thNight
14%5%24423445%48%
2160
16th to endNight
15%7%25%423346%43%
2307
November1st to 15thNight
13%7%26%423345%47%
2530
16th to endNight
15%9%35%42335%5%42%
2730
December1st to 15thNight
16%11%47%6%34445%29%
2575
16th to endNight
20%14%47%6%34345%24%
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
55%414%15%10%
1433
16th to endDay
60%414%14%4
1710
February1st to 15thDay
54%5%13%19%6%
1576
16th to endDay
50%5%12%22%7%1
1503
March1st to 15thDay
48%5%15%20%8%
1938
16th to endDay
54%6%13%20%5%
2139
April1st to 15thDay
51%5%12%21%8%
2151
16th to endDay
55%5%12%18%8%1
2215
May1st to 15thDay
50%7%13%21%6%
2435
16th to endDay
45%6%13%21%11%1
2621
June1st to 15thDay
40%6%15%23%13%
2520
16th to endDay
38%8%12%25%14%1
2520
July1st to 15thDay
33%7%15%27%14%2
2371
16th to endDay
32%9%18%23%14%1
2439
August1st to 15thDay
35%8%14%27%12%1
2326
16th to endDay
39%7%11%25%14%1
2360
September1st to 15thDay
31%6%13%29%17%1
2160
16th to endDay
38%5%12%29%12%
1974
October1st to 15thDay
42%311%23%17%
1800
16th to endDay
43%414%24%11%
1915
November1st to 15thDay
40%412%27%14%1
1655
16th to endDay
45%5%18%23%6%
1560
December1st to 15thDay
60%5%12%14%6%
1467
16th to endDay
65%411%12%6%
1536
January1st to 15thNight
49%5%15%19%10%
2506
16th to endNight
53%415%18%8%
2511
February1st to 15thNight
51%5%13%20%9%
2288
16th to endNight
43%413%25%11%1
1970
March1st to 15thNight
41%412%28%11%1
2034
16th to endNight
52%6%15%18%6%
2084
April1st to 15thNight
46%412%22%12%2
1797
16th to endNight
46%411%23%12%2
1743
May1st to 15thNight
42%8%11%23%12%
1515
16th to endNight
36%7%13%24%15%2
1498
June1st to 15thNight
34%8%16%24%14%1
1440
16th to endNight
31%7%11%25%20%4
1440
July1st to 15thNight
24%6%17%30%17%3
1360
16th to endNight
21%9%17%30%19%2
1466
August1st to 15thNight
27%6%14%31%17%2
1610
16th to endNight
31%6%14%25%17%4
1842
September1st to 15thNight
28%5%8%30%24%1
1800
16th to endNight
29%411%33%18%1
1970
October1st to 15thNight
37%410%24%20%2
2160
16th to endNight
41%5%14%22%15%1
2307
November1st to 15thNight
39%312%24%16%2
2530
16th to endNight
43%415%26%8%
2730
December1st to 15thNight
56%413%17%7%
2575
16th to endNight
62%412%13%6%
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
24%11%33%24%5%1
90
16th to endDay
20%8%33%28%7%2
96
February1st to 15thDay
12%18%37%23%7%
90
16th to endDay
22%12%33%18%13%
81
March1st to 15thDay
22%14%40%16%6%
90
16th to endDay
35%8%29%20%41
123
April1st to 15thDay
22%11%28%29%8%
270
16th to endDay
30%12%27%17%9%2
325
May1st to 15thDay
25%10%29%22%10%2
468
16th to endDay
17%9%29%26%14%2
517
June1st to 15thDay
13%5%26%33%17%3
495
16th to endDay
8%6%34%29%16%3
495
July1st to 15thDay
7%225%34%20%10%
475
16th to endDay
8%223%33%26%6%
515
August1st to 15thDay
9%122%34%25%6%
493
16th to endDay
15%318%34%20%8%
400
September1st to 15thDay
12%224%26%25%8%
315
16th to endDay
12%7%31%28%15%4
207
October1st to 15thDay
22%8%33%18%12%4
135
16th to endDay
21%9%36%25%7%
144
November1st to 15thDay
12%12%32%26%11%4
135
16th to endDay
31%11%32%14%9%
135
December1st to 15thDay
19%15%36%22%8%
100
16th to endDay
29%13%38%15%3
96
January1st to 15thNight
15%10%35%29%9%
900
16th to endNight
16%10%38%29%4
960
February1st to 15thNight
16%9%37%27%8%
880
16th to endNight
15%10%36%28%8%1
708
March1st to 15thNight
19%9%31%28%10%1
594
16th to endNight
19%7%36%26%8%1
576
April1st to 15thNight
19%10%37%27%6%
539
16th to endNight
24%433%29%6%1
540
May1st to 15thNight
18%6%33%31%9%
540
16th to endNight
13%5%31%34%14%
563
June1st to 15thNight
13%227%40%15%
540
16th to endNight
9%328%42%15%
540
July1st to 15thNight
6%19%42%28%2
510
16th to endNight
416%49%25%3
564
August1st to 15thNight
6%217%41%30%2
539
16th to endNight
12%217%37%25%4
573
September1st to 15thNight
13%217%38%23%4
540
16th to endNight
10%427%33%21%1
602
October1st to 15thNight
18%6%32%27%14%
720
16th to endNight
18%10%29%32%8%
768
November1st to 15thNight
16%8%36%29%8%
819
16th to endNight
17%12%38%23%7%
975
December1st to 15thNight
22%9%37%23%5%
920
16th to endNight
26%8%31%24%7%
960
Page generated at 2017-12-05 09:19:05. Version ac04

Copyright 2017 A. Danko


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