Green Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Green Bay clear sky chart from 2005-11-05 to 2018-02-14.

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
37%
16773
16%
48811
9%
16730
44%
16730
24%
32828

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
25%
975
13%
2716
5%
970
31%
970
18%
1987
January16th to endNight
24%
1040
13%
2912
3%
1040
31%
1040
17%
2165
February1st to 15thNight
26%
907
15%
2458
4%
906
34%
906
21%
1745
February16th to endNight
29%
631
15%
1893
7%
631
36%
631
17%
1347
March1st to 15thNight
36%
720
15%
2160
9%
720
41%
720
23%
1445
March16th to endNight
36%
629
18%
2015
14%
629
42%
629
22%
1363
April1st to 15thNight
29%
539
16%
1797
10%
539
39%
539
19%
1222
April16th to endNight
38%
540
19%
1695
12%
540
45%
540
23%
1114
May1st to 15thNight
33%
540
16%
1527
8%
540
40%
540
23%
1067
May16th to endNight
47%
562
16%
1498
9%
561
53%
561
33%
962
June1st to 15thNight
47%
540
13%
1440
6%
540
51%
540
29%
939
June16th to endNight
53%
540
14%
1440
8%
540
56%
540
33%
922
July1st to 15thNight
66%
510
16%
1360
10%
510
68%
510
43%
788
July16th to endNight
61%
564
19%
1417
11%
531
66%
531
44%
825
August1st to 15thNight
68%
539
21%
1473
16%
536
71%
536
37%
889
August16th to endNight
60%
573
21%
1899
20%
573
65%
573
31%
1109
September1st to 15thNight
59%
540
25%
1800
24%
540
65%
540
35%
985
September16th to endNight
54%
717
22%
1980
15%
717
58%
717
34%
1213
October1st to 15thNight
40%
720
20%
2087
13%
720
46%
720
27%
1354
October16th to endNight
30%
768
14%
2472
8%
768
38%
768
19%
1696
November1st to 15thNight
29%
760
20%
2471
12%
760
39%
760
22%
1587
November16th to endNight
27%
904
15%
2659
7%
904
35%
904
18%
1860
December1st to 15thNight
20%
975
11%
2730
2%
975
27%
975
17%
2001
December16th to endNight
21%
1040
13%
2912
3%
1040
30%
1040
15%
2243

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%36%5%35%45%7%37%
49275
Night
13%8%36%5%34446%39%
48979
Cloud CoverDay
13%7%36%5%35%45%7%37%
49284
Night
13%8%36%5%34446%39%
48984
TransparencyDay
45%6%13%23%10%1
48961
Night
44%5%12%23%11%1
48811
SeeingDay
15%7%28%28%15%4
6552
Night
17%6%30%32%12%1
16776

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
13%10%6%7%6%35%446%30%
1552
16th to endDay
12%13%5%10%7%46%346%25%
1664
February1st to 15thDay
11%12%46%7%2435%6%34%
1702
16th to endDay
12%12%47%5%35%5%46%32%
1580
March1st to 15thDay
14%10%45%43446%6%35%
1790
16th to endDay
15%9%46%435%446%35%
2220
April1st to 15thDay
16%10%46%5%3445%7%31%
2151
16th to endDay
19%8%25%5%34446%35%
2265
May1st to 15thDay
16%7%36%6%445%45%35%
2422
16th to endDay
10%5%245%25%5%6%9%41%
2617
June1st to 15thDay
12%5%25%5%35%46%7%41%
2520
16th to endDay
10%425%5%35%5%6%9%40%
2520
July1st to 15thDay
6%3245%35%6%5%9%47%
2520
16th to endDay
8%5%245%35%5%7%9%42%
2655
August1st to 15thDay
7%425%6%35%6%6%9%42%
2476
16th to endDay
12%5%25%5%3445%7%43%
2300
September1st to 15thDay
12%5%26%425%45%7%44%
2148
16th to endDay
9%6%35%6%36%46%7%39%
1980
October1st to 15thDay
17%6%35%434346%40%
1872
16th to endDay
17%9%37%6%24446%33%
1751
November1st to 15thDay
15%8%36%5%25%46%7%35%
1717
16th to endDay
13%10%48%5%3445%6%33%
1629
December1st to 15thDay
16%11%37%5%35%45%5%30%
1560
16th to endDay
17%13%6%10%7%35%445%21%
1664
January1st to 15thNight
13%13%5%7%6%3433433%
2716
16th to endNight
11%11%5%9%7%36%45%6%28%
2912
February1st to 15thNight
8%12%5%8%6%2444437%
2456
16th to endNight
13%12%48%6%34445%32%
1893
March1st to 15thNight
13%8%36%434445%41%
2147
16th to endNight
15%8%36%5%2445%5%38%
2015
April1st to 15thNight
19%8%36%434347%35%
1797
16th to endNight
18%7%35%423446%39%
1695
May1st to 15thNight
18%5%36%43446%7%34%
1527
16th to endNight
10%5%234345%6%9%44%
1496
June1st to 15thNight
11%6%245%345%6%8%42%
1440
16th to endNight
9%3245%25%6%6%9%44%
1440
July1st to 15thNight
5%3134345%5%8%54%
1440
16th to endNight
5%31442446%8%53%
1513
August1st to 15thNight
6%3144445%6%9%48%
1482
16th to endNight
8%5%245%2445%7%49%
1899
September1st to 15thNight
8%41333435%7%54%
1800
16th to endNight
11%5%15%42335%7%48%
1980
October1st to 15thNight
15%6%25%423446%44%
2087
16th to endNight
15%9%26%6%34446%35%
2472
November1st to 15thNight
15%8%35%423346%41%
2471
16th to endNight
16%9%36%5%34447%33%
2659
December1st to 15thNight
15%11%48%6%33445%31%
2730
16th to endNight
18%14%5%7%6%34335%27%
2912

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
12%10%6%8%5%36%445%31%
1552
16th to endDay
12%13%6%10%6%45%346%26%
1664
February1st to 15thDay
11%12%5%6%6%2445%6%34%
1702
16th to endDay
13%11%47%5%35%5%5%6%32%
1580
March1st to 15thDay
14%10%45%4345%5%7%35%
1800
16th to endDay
15%9%46%5%34446%34%
2219
April1st to 15thDay
16%10%46%5%3435%7%31%
2151
16th to endDay
20%8%345%34446%34%
2265
May1st to 15thDay
16%6%37%6%35%446%35%
2422
16th to endDay
10%424435%5%6%9%42%
2617
June1st to 15thDay
12%5%25%5%25%5%6%7%41%
2520
16th to endDay
10%5%25%5%35%5%6%9%41%
2520
July1st to 15thDay
6%3245%35%5%5%10%47%
2520
16th to endDay
8%4245%35%5%7%9%42%
2655
August1st to 15thDay
7%4246%35%6%7%9%42%
2476
16th to endDay
12%5%25%43445%7%44%
2300
September1st to 15thDay
12%6%15%42445%8%44%
2148
16th to endDay
9%6%36%6%35%5%6%8%38%
1980
October1st to 15thDay
17%6%26%43435%6%40%
1872
16th to endDay
17%9%37%6%33346%32%
1751
November1st to 15thDay
15%7%36%5%25%5%47%35%
1717
16th to endDay
14%10%47%5%35%347%32%
1629
December1st to 15thDay
15%11%37%6%345%5%6%30%
1560
16th to endDay
17%14%6%10%7%34445%21%
1664
January1st to 15thNight
13%12%5%7%6%3433433%
2716
16th to endNight
11%10%5%9%7%45%45%6%28%
2912
February1st to 15thNight
9%13%5%8%5%2444437%
2449
16th to endNight
14%12%38%6%345%35%32%
1893
March1st to 15thNight
13%8%35%434445%41%
2160
16th to endNight
15%7%46%425%446%38%
2015
April1st to 15thNight
19%8%36%5%3425%6%35%
1797
16th to endNight
18%8%25%423446%39%
1695
May1st to 15thNight
18%5%26%5%35%46%7%34%
1526
16th to endNight
10%5%244335%6%9%44%
1496
June1st to 15thNight
11%6%245%345%6%8%42%
1440
16th to endNight
9%4245%25%6%6%9%44%
1440
July1st to 15thNight
5%31443345%8%54%
1440
16th to endNight
5%31432447%9%53%
1513
August1st to 15thNight
6%414435%45%10%48%
1482
16th to endNight
8%5%2443445%7%49%
1899
September1st to 15thNight
9%41442335%7%54%
1800
16th to endNight
11%425%5%2425%7%49%
1980
October1st to 15thNight
15%6%25%42335%6%44%
2087
16th to endNight
16%8%36%5%44446%35%
2472
November1st to 15thNight
15%8%25%5%23346%40%
2471
16th to endNight
16%9%45%6%35%45%7%33%
2659
December1st to 15thNight
15%11%48%6%34446%31%
2730
16th to endNight
18%13%5%7%5%34335%28%
2912

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
54%5%11%18%9%1
1553
16th to endDay
59%412%16%6%
1664
February1st to 15thDay
49%5%12%22%8%1
1704
16th to endDay
51%5%12%20%8%1
1580
March1st to 15thDay
47%5%15%21%8%1
1800
16th to endDay
49%5%15%21%6%1
2220
April1st to 15thDay
51%5%10%20%10%
2151
16th to endDay
50%411%19%12%1
2265
May1st to 15thDay
49%5%12%22%9%1
2422
16th to endDay
36%7%13%25%14%1
2621
June1st to 15thDay
40%6%14%26%11%
2520
16th to endDay
37%7%16%23%13%
2520
July1st to 15thDay
31%6%14%30%15%2
2371
16th to endDay
35%7%13%25%15%2
2488
August1st to 15thDay
35%7%14%30%10%1
2461
16th to endDay
38%7%12%26%14%1
2300
September1st to 15thDay
37%5%12%30%13%
2148
16th to endDay
40%6%16%27%9%
1980
October1st to 15thDay
44%5%14%25%9%
1872
16th to endDay
52%5%12%22%6%
1751
November1st to 15thDay
46%5%13%22%11%
1717
16th to endDay
51%5%17%19%4
1629
December1st to 15thDay
53%5%13%19%7%
1560
16th to endDay
65%310%12%7%
1664
January1st to 15thNight
54%410%18%11%
2716
16th to endNight
54%5%13%19%6%
2912
February1st to 15thNight
50%410%23%9%2
2458
16th to endNight
54%313%20%7%1
1893
March1st to 15thNight
44%5%13%22%12%1
2160
16th to endNight
47%412%24%9%1
2015
April1st to 15thNight
49%47%22%13%1
1797
16th to endNight
45%311%22%14%2
1695
May1st to 15thNight
47%5%13%20%11%1
1527
16th to endNight
35%6%14%27%14%1
1498
June1st to 15thNight
38%6%12%27%13%
1440
16th to endNight
33%8%14%24%15%2
1440
July1st to 15thNight
27%5%13%32%16%4
1360
16th to endNight
25%6%17%28%18%2
1417
August1st to 15thNight
30%6%15%31%14%1
1473
16th to endNight
32%6%12%27%17%2
1899
September1st to 15thNight
29%5%11%31%20%1
1800
16th to endNight
34%414%33%11%1
1980
October1st to 15thNight
41%5%10%28%13%1
2087
16th to endNight
48%6%14%20%10%
2472
November1st to 15thNight
44%411%24%13%1
2471
16th to endNight
49%416%20%7%
2659
December1st to 15thNight
54%415%18%7%
2730
16th to endNight
59%412%15%7%
2912

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
17%10%34%29%7%
135
16th to endDay
20%9%28%33%7%
144
February1st to 15thDay
11%12%46%23%5%
130
16th to endDay
17%16%33%19%12%1
81
March1st to 15thDay
24%16%25%22%10%1
90
16th to endDay
26%8%21%29%12%1
246
April1st to 15thDay
25%9%26%26%10%1
270
16th to endDay
25%8%30%18%13%3
270
May1st to 15thDay
20%10%32%24%9%3
379
16th to endDay
13%8%33%26%13%5%
517
June1st to 15thDay
15%6%28%33%13%2
495
16th to endDay
12%5%31%30%15%4
495
July1st to 15thDay
8%5%21%35%21%7%
475
16th to endDay
7%426%34%18%7%
515
August1st to 15thDay
11%217%35%25%7%
449
16th to endDay
15%417%28%25%8%
332
September1st to 15thDay
13%420%27%21%11%
315
16th to endDay
11%5%21%31%23%5%
314
October1st to 15thDay
15%11%27%26%14%4
207
16th to endDay
19%13%37%23%6%
144
November1st to 15thDay
15%13%34%23%10%2
135
16th to endDay
20%20%37%14%7%
135
December1st to 15thDay
21%11%48%14%2
135
16th to endDay
27%18%40%11%2
144
January1st to 15thNight
18%8%36%28%6%
975
16th to endNight
16%8%38%29%6%
1040
February1st to 15thNight
15%8%36%31%7%
909
16th to endNight
19%6%34%30%7%
631
March1st to 15thNight
17%7%33%32%8%1
720
16th to endNight
18%6%31%31%11%1
629
April1st to 15thNight
24%5%34%28%7%
539
16th to endNight
20%5%30%34%8%
540
May1st to 15thNight
20%6%34%29%8%
540
16th to endNight
12%429%38%14%
563
June1st to 15thNight
14%5%24%40%14%
540
16th to endNight
11%226%43%15%
540
July1st to 15thNight
7%118%46%24%
510
16th to endNight
7%121%42%25%1
564
August1st to 15thNight
7%114%48%25%2
539
16th to endNight
10%121%38%25%2
573
September1st to 15thNight
11%321%31%25%6%
540
16th to endNight
13%420%34%23%2
717
October1st to 15thNight
20%7%27%27%15%1
720
16th to endNight
20%8%33%27%9%
768
November1st to 15thNight
18%9%36%26%7%
760
16th to endNight
19%13%31%27%7%
904
December1st to 15thNight
22%9%38%22%5%
975
16th to endNight
23%10%34%26%5%
1040
Page generated at 2018-02-15 09:58:50. Version ac04

Copyright 2018 A. Danko


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