Madison
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Madison clear sky chart from 2005-11-05 to 2018-02-22.

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
36%
16753
17%
48912
10%
16710
43%
16710
23%
32752

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
23%
975
14%
2716
5%
970
31%
970
18%
1972
January16th to endNight
21%
1040
12%
2856
3%
1040
28%
1040
17%
2134
February1st to 15thNight
23%
934
15%
2466
4%
934
31%
934
21%
1753
February16th to endNight
26%
659
18%
1977
7%
659
36%
659
18%
1381
March1st to 15thNight
29%
717
16%
2157
9%
717
35%
717
20%
1453
March16th to endNight
31%
576
16%
1999
13%
576
38%
576
18%
1382
April1st to 15thNight
27%
539
16%
1797
10%
539
37%
539
18%
1223
April16th to endNight
34%
540
19%
1758
13%
540
43%
540
22%
1163
May1st to 15thNight
32%
540
15%
1506
8%
540
39%
540
22%
1071
May16th to endNight
45%
563
16%
1497
8%
561
51%
561
32%
962
June1st to 15thNight
51%
540
15%
1440
9%
540
54%
540
31%
931
June16th to endNight
51%
540
16%
1440
9%
540
55%
540
36%
903
July1st to 15thNight
66%
510
19%
1360
11%
510
69%
510
44%
774
July16th to endNight
68%
564
21%
1417
14%
531
70%
531
43%
825
August1st to 15thNight
69%
539
21%
1536
19%
536
71%
536
37%
904
August16th to endNight
63%
573
20%
1910
21%
573
66%
573
31%
1109
September1st to 15thNight
60%
540
27%
1800
26%
540
67%
540
36%
971
September16th to endNight
55%
684
27%
1947
19%
684
61%
684
36%
1137
October1st to 15thNight
41%
720
22%
2133
15%
720
46%
720
29%
1333
October16th to endNight
33%
768
19%
2415
11%
768
42%
768
22%
1577
November1st to 15thNight
31%
760
22%
2471
15%
760
40%
760
23%
1564
November16th to endNight
24%
917
16%
2672
7%
917
34%
917
20%
1845
December1st to 15thNight
20%
975
11%
2730
3%
975
27%
975
15%
2055
December16th to endNight
16%
1040
12%
2912
3%
1040
23%
1040
12%
2330

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%3445%7%37%
49348
Night
13%8%35%5%24447%39%
49080
Cloud CoverDay
13%7%36%5%3445%7%36%
49356
Night
13%8%35%5%24446%39%
49085
TransparencyDay
46%5%12%22%11%1
49033
Night
44%5%11%23%13%1
48913
SeeingDay
15%7%28%26%15%5%
6531
Night
18%7%31%29%12%1
16756

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
11%11%5%8%445%5%5%7%29%
1552
16th to endDay
12%12%6%12%8%345%5%7%22%
1719
February1st to 15thDay
12%13%6%7%5%24446%32%
1726
16th to endDay
14%10%46%6%35%35%5%32%
1643
March1st to 15thDay
14%8%5%7%4235%5%6%36%
1804
16th to endDay
17%8%36%5%34447%34%
2224
April1st to 15thDay
17%9%46%6%245%5%6%29%
2151
16th to endDay
19%8%37%5%34335%35%
2200
May1st to 15thDay
18%8%36%7%35%5%6%6%30%
2443
16th to endDay
13%6%25%5%35%5%5%8%38%
2617
June1st to 15thDay
12%5%25%5%45%5%5%8%38%
2520
16th to endDay
9%425%6%35%5%6%10%40%
2520
July1st to 15thDay
7%324435%5%7%9%45%
2520
16th to endDay
8%5%15%5%36%6%6%9%41%
2655
August1st to 15thDay
7%425%6%35%6%6%10%42%
2414
16th to endDay
11%5%245%35%45%8%43%
2292
September1st to 15thDay
12%41442445%7%47%
2160
16th to endDay
10%5%25%5%3335%8%45%
2001
October1st to 15thDay
16%6%35%423335%44%
1824
16th to endDay
15%8%35%6%43247%37%
1807
November1st to 15thDay
13%8%36%5%3335%6%40%
1717
16th to endDay
14%10%5%6%6%33336%37%
1615
December1st to 15thDay
15%12%5%8%5%35%347%28%
1560
16th to endDay
18%15%7%9%6%34445%20%
1664
January1st to 15thNight
14%10%5%8%5%24346%33%
2716
16th to endNight
12%10%6%9%7%35%45%6%29%
2856
February1st to 15thNight
11%12%46%5%235%46%36%
2463
16th to endNight
15%9%47%434346%34%
1977
March1st to 15thNight
15%9%34424446%39%
2144
16th to endNight
17%8%36%435%5%46%33%
1999
April1st to 15thNight
18%8%25%435%5%45%35%
1797
16th to endNight
18%7%25%433447%38%
1758
May1st to 15thNight
18%6%25%5%246%6%6%35%
1506
16th to endNight
10%5%245%245%5%10%42%
1496
June1st to 15thNight
11%5%145%245%5%10%42%
1440
16th to endNight
8%5%2442446%9%48%
1440
July1st to 15thNight
6%21332446%8%56%
1440
16th to endNight
5%313425%449%55%
1513
August1st to 15thNight
5%4245%245%6%9%50%
1545
16th to endNight
10%5%14425%447%50%
1910
September1st to 15thNight
9%314423346%56%
1800
16th to endNight
7%4235%2445%8%51%
1947
October1st to 15thNight
13%6%25%323346%46%
2133
16th to endNight
14%8%25%424447%40%
2415
November1st to 15thNight
13%7%25%424446%44%
2471
16th to endNight
16%8%36%424446%37%
2672
December1st to 15thNight
18%11%48%6%34445%29%
2730
16th to endNight
20%13%5%7%6%35%44423%
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
11%11%5%8%5%35%5%5%7%29%
1552
16th to endDay
12%13%6%12%7%3445%7%22%
1719
February1st to 15thDay
12%13%6%7%424446%32%
1726
16th to endDay
14%10%47%6%45%35%5%32%
1643
March1st to 15thDay
14%9%5%6%4245%47%35%
1814
16th to endDay
17%8%36%5%34447%33%
2222
April1st to 15thDay
17%10%5%6%6%245%5%7%29%
2151
16th to endDay
19%8%36%5%34345%35%
2200
May1st to 15thDay
18%7%36%6%345%6%6%29%
2443
16th to endDay
13%6%25%5%35%45%8%39%
2617
June1st to 15thDay
12%5%25%436%46%9%38%
2520
16th to endDay
8%425%6%35%5%6%11%39%
2520
July1st to 15thDay
7%315%5%35%5%7%9%45%
2520
16th to endDay
7%5%146%26%6%6%9%41%
2655
August1st to 15thDay
7%315%6%35%5%7%10%42%
2414
16th to endDay
11%5%245%35%5%5%7%43%
2292
September1st to 15thDay
12%41442445%7%47%
2160
16th to endDay
9%5%36%5%24348%46%
2001
October1st to 15thDay
16%6%36%422336%44%
1824
16th to endDay
15%9%35%6%33347%37%
1807
November1st to 15thDay
13%8%26%5%33347%40%
1717
16th to endDay
14%10%47%5%23336%37%
1615
December1st to 15thDay
15%13%5%8%5%35%347%27%
1560
16th to endDay
18%15%7%8%7%34445%20%
1664
January1st to 15thNight
14%10%5%8%5%24346%33%
2716
16th to endNight
12%11%6%9%6%35%45%6%29%
2856
February1st to 15thNight
11%12%47%4245%46%36%
2456
16th to endNight
15%9%47%434346%34%
1977
March1st to 15thNight
16%9%3443445%6%38%
2157
16th to endNight
17%9%35%435%5%47%33%
1999
April1st to 15thNight
19%7%35%435%45%5%35%
1797
16th to endNight
18%7%25%423446%39%
1758
May1st to 15thNight
19%6%345%246%5%6%35%
1505
16th to endNight
10%6%235%345%6%10%42%
1496
June1st to 15thNight
11%5%25%5%245%5%9%43%
1440
16th to endNight
9%42442346%8%48%
1440
July1st to 15thNight
6%21332346%8%56%
1440
16th to endNight
5%2235%2445%9%55%
1513
August1st to 15thNight
5%4245%245%7%8%49%
1545
16th to endNight
9%5%24424447%49%
1910
September1st to 15thNight
9%313423446%56%
1800
16th to endNight
7%4244345%5%7%51%
1947
October1st to 15thNight
14%6%15%423346%46%
2133
16th to endNight
15%8%25%5%2345%7%40%
2415
November1st to 15thNight
13%7%25%5%24335%44%
2471
16th to endNight
16%8%45%5%24445%37%
2672
December1st to 15thNight
18%11%47%6%34445%29%
2730
16th to endNight
20%13%5%8%6%3444423%
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
53%414%17%9%
1553
16th to endDay
60%412%14%6%
1719
February1st to 15thDay
54%412%20%7%1
1727
16th to endDay
53%411%20%8%1
1643
March1st to 15thDay
48%6%13%21%9%1
1814
16th to endDay
51%413%22%6%
2224
April1st to 15thDay
54%5%10%20%9%
2151
16th to endDay
52%410%20%10%2
2200
May1st to 15thDay
53%5%12%20%7%
2443
16th to endDay
43%7%11%22%13%1
2621
June1st to 15thDay
42%7%12%24%13%
2520
16th to endDay
37%7%15%22%14%1
2520
July1st to 15thDay
33%8%14%25%16%1
2371
16th to endDay
36%7%15%23%13%2
2488
August1st to 15thDay
36%7%13%29%12%1
2399
16th to endDay
38%6%12%25%14%1
2292
September1st to 15thDay
35%5%10%28%20%
2160
16th to endDay
37%5%12%30%14%
2001
October1st to 15thDay
43%49%25%16%
1824
16th to endDay
47%412%25%10%
1807
November1st to 15thDay
44%413%24%12%1
1717
16th to endDay
50%416%22%5%
1615
December1st to 15thDay
56%314%17%7%
1560
16th to endDay
65%311%11%7%
1664
January1st to 15thNight
53%49%19%12%
2716
16th to endNight
55%414%17%7%
2856
February1st to 15thNight
49%411%21%11%1
2466
16th to endNight
50%411%22%9%2
1977
March1st to 15thNight
46%5%13%19%13%1
2157
16th to endNight
51%411%23%7%1
1999
April1st to 15thNight
48%5%7%22%15%1
1797
16th to endNight
46%49%22%13%2
1758
May1st to 15thNight
48%6%10%20%13%
1506
16th to endNight
36%7%14%24%15%2
1498
June1st to 15thNight
36%6%11%26%17%
1440
16th to endNight
32%6%14%22%20%2
1440
July1st to 15thNight
24%6%11%32%20%3
1360
16th to endNight
25%7%14%29%17%4
1417
August1st to 15thNight
29%6%11%30%19%1
1536
16th to endNight
34%5%12%27%17%3
1910
September1st to 15thNight
28%5%10%27%26%1
1800
16th to endNight
31%5%10%33%18%
1947
October1st to 15thNight
39%49%25%19%1
2133
16th to endNight
44%412%25%13%
2415
November1st to 15thNight
42%410%23%16%2
2471
16th to endNight
47%5%14%22%9%1
2672
December1st to 15thNight
57%411%19%7%
2730
16th to endNight
64%49%13%6%
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%31%5%
135
16th to endDay
19%11%34%27%6%
144
February1st to 15thDay
16%14%45%17%6%
135
16th to endDay
31%14%34%14%7%
100
March1st to 15thDay
27%10%38%18%31
90
16th to endDay
28%6%30%21%9%3
208
April1st to 15thDay
21%10%33%25%8%
270
16th to endDay
25%9%25%23%12%3
270
May1st to 15thDay
23%10%29%26%8%2
400
16th to endDay
18%9%28%24%15%3
517
June1st to 15thDay
13%6%28%30%17%3
495
16th to endDay
9%7%33%28%15%6%
495
July1st to 15thDay
9%322%32%21%11%
475
16th to endDay
8%226%30%22%9%
515
August1st to 15thDay
8%219%34%23%11%
469
16th to endDay
14%5%15%28%23%12%
332
September1st to 15thDay
11%320%26%25%12%
315
16th to endDay
10%425%28%23%7%
314
October1st to 15thDay
18%9%30%23%15%2
159
16th to endDay
22%11%34%25%6%
144
November1st to 15thDay
13%13%33%22%11%5%
135
16th to endDay
25%11%39%17%5%
135
December1st to 15thDay
18%17%42%16%4
135
16th to endDay
18%23%42%13%2
144
January1st to 15thNight
20%12%37%22%6%
975
16th to endNight
18%10%40%26%3
1040
February1st to 15thNight
19%8%39%26%6%
937
16th to endNight
21%10%35%26%5%
659
March1st to 15thNight
22%9%33%25%9%
717
16th to endNight
21%6%32%28%8%1
576
April1st to 15thNight
23%9%35%25%5%
539
16th to endNight
23%6%31%28%8%
540
May1st to 15thNight
22%5%33%29%8%
540
16th to endNight
13%428%39%14%
563
June1st to 15thNight
14%324%41%16%
540
16th to endNight
10%327%39%17%
540
July1st to 15thNight
8%20%39%28%2
510
16th to endNight
6%18%46%25%2
564
August1st to 15thNight
7%14%48%25%3
539
16th to endNight
12%16%39%26%4
573
September1st to 15thNight
11%221%32%26%5%
540
16th to endNight
9%424%33%24%2
684
October1st to 15thNight
18%5%29%30%15%1
720
16th to endNight
19%10%32%28%8%
768
November1st to 15thNight
18%9%35%25%10%
760
16th to endNight
20%12%35%22%8%
917
December1st to 15thNight
24%11%36%21%5%
975
16th to endNight
27%10%34%23%4
1040
Page generated at 2018-02-23 10:21:29. Version ac04

Copyright 2018 A. Danko


Madison Clear Sky Chart |Charts Home