Marquette
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Marquette clear sky chart from 2005-11-06 to 2024-03-23.

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
27%
25115
7%
81405
4%
25012
30%
25012
8%
67482

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 10thNight
11%
943
6%
4395
1%
926
14%
926
3%
3745
January11th to 20thNight
11%
949
4%
4410
0%
930
14%
930
2%
3821
January21st to endNight
14%
1033
3%
4883
1%
1023
17%
1023
3%
4006
February1st to 10thNight
17%
950
6%
2608
2%
950
20%
950
7%
2242
February11th to 20thNight
18%
791
8%
2267
3%
788
22%
788
7%
1928
February21st to endNight
14%
628
5%
1884
0%
628
18%
628
6%
1639
March1st to 10thNight
27%
760
9%
2278
5%
759
30%
759
10%
1887
March11th to 20thNight
23%
760
11%
2228
6%
760
28%
760
9%
1833
March21st to endNight
28%
624
8%
2024
6%
624
32%
624
8%
1699
April1st to 10thNight
25%
540
5%
1800
3%
540
27%
540
7%
1490
April11th to 20thNight
31%
533
11%
1736
7%
533
36%
533
10%
1395
April21st to endNight
32%
540
9%
1620
5%
540
36%
540
11%
1303
May1st to 10thNight
39%
540
9%
1530
6%
540
41%
540
11%
1252
May11th to 20thNight
39%
531
11%
1416
6%
531
43%
531
11%
1172
May21st to endNight
43%
583
10%
1552
5%
582
46%
582
15%
1222
June1st to 10thNight
45%
540
8%
1440
4%
540
48%
540
16%
1120
June11th to 20thNight
41%
460
7%
1360
5%
460
43%
460
14%
1058
June21st to endNight
42%
540
8%
1440
3%
540
45%
540
15%
1142
July1st to 10thNight
54%
525
9%
1400
5%
525
56%
525
20%
1036
July11th to 20thNight
44%
522
10%
1392
5%
522
47%
522
16%
1063
July21st to endNight
53%
591
11%
1487
6%
558
55%
558
20%
1089
August1st to 10thNight
51%
537
12%
1423
7%
534
55%
534
18%
1087
August11th to 20thNight
57%
534
17%
1551
10%
534
64%
534
21%
1086
August21st to endNight
45%
594
11%
1957
8%
594
48%
594
16%
1413
September1st to 10thNight
48%
540
12%
1800
10%
540
53%
540
15%
1306
September11th to 20thNight
38%
643
12%
1903
8%
643
42%
643
15%
1458
September21st to endNight
36%
720
8%
1980
4%
720
39%
720
13%
1588
October1st to 10thNight
28%
720
12%
2037
6%
720
33%
720
13%
1604
October11th to 20thNight
21%
720
6%
2268
2%
720
26%
720
8%
1900
October21st to endNight
18%
792
5%
2574
2%
792
22%
792
6%
2241
November1st to 10thNight
19%
740
8%
2406
3%
740
25%
740
8%
1984
November11th to 20thNight
12%
802
8%
2512
2%
802
18%
802
4%
2205
November21st to endNight
14%
950
6%
2660
2%
950
17%
950
7%
2334
December1st to 10thNight
11%
950
2%
2838
0%
950
13%
950
4%
2519
December11th to 20thNight
11%
949
4%
3469
0%
948
15%
948
3%
3015
December21st to endNight
8%
1041
2%
4877
0%
1026
11%
1026
1%
4600

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%10%5%8%7%45%5%5%7%31%
78153
Night
14%12%6%10%7%45%5%5%6%28%
81672
TransparencyDay
37%37%8%12%5%
77859
Night
39%36%8%12%5%1
81501
SeeingDay
18%14%34%24%9%2
14933
Night
19%13%33%25%9%1
25141

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 10thDay
10%16%13%14%7%46%45%7%14%
2527
11th to 20thDay
9%14%7%16%14%6%6%5%7%5%11%
2530
21st to endDay
9%17%9%15%10%6%5%5%5%5%14%
2783
February1st to 10thDay
10%12%5%13%11%7%6%5%5%6%21%
1571
11th to 20thDay
9%11%412%10%6%8%6%6%6%22%
1799
21st to endDay
12%12%6%12%9%47%5%6%6%21%
1570
March1st to 10thDay
10%12%6%10%7%5%6%6%5%6%27%
1898
11th to 20thDay
11%11%7%11%8%345%46%31%
1950
21st to endDay
14%12%5%9%6%35%5%6%7%25%
2392
April1st to 10thDay
15%11%6%8%6%35%5%5%7%28%
2160
11th to 20thDay
20%12%48%5%3445%5%30%
2173
21st to endDay
15%10%46%5%36%6%5%7%33%
2340
May1st to 10thDay
15%9%37%5%35%45%8%36%
2427
11th to 20thDay
16%9%45%5%35%45%6%39%
2479
21st to endDay
11%6%25%6%35%5%6%9%41%
2725
June1st to 10thDay
11%7%36%6%36%5%5%9%40%
2520
11th to 20thDay
16%6%26%5%35%5%7%8%38%
2520
21st to endDay
15%5%26%6%35%6%6%9%39%
2520
July1st to 10thDay
8%325%5%35%5%6%11%48%
2520
11th to 20thDay
10%5%245%345%6%10%46%
2520
21st to endDay
9%424435%47%9%49%
2743
August1st to 10thDay
10%4245%35%6%6%9%47%
2507
11th to 20thDay
11%5%245%345%6%8%45%
2350
21st to endDay
14%5%245%245%6%8%45%
2396
September1st to 10thDay
16%6%245%35%5%5%8%42%
2160
11th to 20thDay
15%5%346%345%6%8%40%
2039
21st to endDay
20%8%36%5%35%6%6%7%30%
1980
October1st to 10thDay
19%10%35%5%45%6%6%7%30%
1922
11th to 20thDay
24%12%48%6%36%6%6%6%19%
1692
21st to endDay
21%20%6%8%7%445%45%18%
1782
November1st to 10thDay
17%15%48%6%25%46%6%26%
1672
11th to 20thDay
15%16%8%11%9%46%45%5%17%
1663
21st to endDay
15%18%9%13%8%34446%16%
1520
December1st to 10thDay
10%14%11%17%7%5%5%5%45%17%
1335
11th to 20thDay
15%17%8%17%7%45%445%14%
1685
21st to endDay
17%21%12%14%9%444337%
2783
January1st to 10thNight
13%17%8%19%7%4334318%
4428
11th to 20thNight
9%16%7%17%12%6%6%44414%
4440
21st to endNight
12%14%9%13%9%5%5%5%5%6%16%
4884
February1st to 10thNight
8%13%8%11%10%5%8%5%5%5%21%
2608
11th to 20thNight
10%11%5%12%11%5%6%6%5%6%23%
2266
21st to endNight
13%14%7%12%8%46%446%22%
1884
March1st to 10thNight
10%9%5%9%7%45%5%5%7%33%
2269
11th to 20thNight
11%12%6%10%7%45%445%32%
2228
21st to endNight
16%12%6%8%6%35%45%6%30%
2024
April1st to 10thNight
18%13%48%7%35%6%5%6%26%
1800
11th to 20thNight
22%8%45%5%3445%6%35%
1736
21st to endNight
16%10%47%5%35%45%6%35%
1620
May1st to 10thNight
16%9%47%5%35%6%6%7%33%
1530
11th to 20thNight
17%9%35%5%35%5%5%6%36%
1416
21st to endNight
14%5%25%435%6%5%9%41%
1551
June1st to 10thNight
14%5%36%5%445%47%43%
1440
11th to 20thNight
14%7%36%6%36%6%6%7%36%
1360
21st to endNight
16%6%35%4245%6%9%40%
1440
July1st to 10thNight
10%3245%3446%8%50%
1440
11th to 20thNight
11%425%6%245%6%7%47%
1440
21st to endNight
8%3245%2335%9%55%
1575
August1st to 10thNight
8%5%245%25%47%7%51%
1432
11th to 20thNight
8%5%25%6%34448%52%
1551
21st to endNight
13%5%25%424446%50%
1957
September1st to 10thNight
13%5%345%3345%7%48%
1800
11th to 20thNight
13%6%36%5%35%5%5%5%43%
1903
21st to endNight
19%7%26%5%25%6%5%8%36%
1980
October1st to 10thNight
18%7%27%5%345%6%6%36%
2037
11th to 20thNight
19%12%36%6%35%46%7%28%
2268
21st to endNight
20%17%5%8%7%445%5%5%21%
2574
November1st to 10thNight
14%15%5%7%6%45%5%6%7%26%
2406
11th to 20thNight
16%17%8%10%7%4444421%
2512
21st to endNight
16%15%9%12%7%3445%6%18%
2660
December1st to 10thNight
11%15%10%12%8%45%5%5%5%19%
2838
11th to 20thNight
13%14%7%17%8%45%5%45%17%
3491
21st to endNight
19%22%13%13%7%344339%
4884

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 10thDay
53%28%9%8%1
2528
11th to 20thDay
55%28%7%8%
2530
21st to endDay
56%27%10%5%2
2783
February1st to 10thDay
44%35%7%9%4
1571
11th to 20thDay
44%36%7%9%3
1809
21st to endDay
46%34%8%7%41
1570
March1st to 10thDay
43%37%7%8%5%
1900
11th to 20thDay
38%36%9%11%5%1
1950
21st to endDay
42%38%9%8%2
2392
April1st to 10thDay
37%38%8%13%4
2160
11th to 20thDay
40%36%6%12%6%
2173
21st to endDay
35%38%6%11%8%2
2340
May1st to 10thDay
33%39%8%13%7%
2427
11th to 20thDay
31%37%7%15%10%1
2483
21st to endDay
26%40%10%14%10%1
2725
June1st to 10thDay
28%39%9%16%8%1
2520
11th to 20thDay
27%38%9%15%10%1
2520
21st to endDay
28%40%9%16%6%1
2520
July1st to 10thDay
21%40%10%21%7%
2451
11th to 20thDay
23%41%9%17%10%1
2445
21st to endDay
23%41%10%17%8%
2591
August1st to 10thDay
24%40%11%18%7%1
2492
11th to 20thDay
22%38%10%20%9%
2350
21st to endDay
26%39%11%16%9%1
2396
September1st to 10thDay
26%38%9%19%7%
2160
11th to 20thDay
30%40%12%16%3
2039
21st to endDay
35%39%9%13%4
1980
October1st to 10thDay
34%38%8%16%3
1922
11th to 20thDay
45%38%9%8%1
1692
21st to endDay
45%38%6%9%1
1782
November1st to 10thDay
35%41%8%11%5%
1672
11th to 20thDay
42%41%7%7%3
1663
21st to endDay
43%42%7%7%1
1520
December1st to 10thDay
45%41%7%6%1
1335
11th to 20thDay
53%32%7%6%1
1685
21st to endDay
65%28%33
2783
January1st to 10thNight
55%26%5%12%1
4428
11th to 20thNight
55%29%8%9%1
4440
21st to endNight
51%27%13%7%2
4884
February1st to 10thNight
41%37%6%10%6%
2608
11th to 20thNight
41%36%8%10%5%
2267
21st to endNight
45%35%8%8%3
1884
March1st to 10thNight
38%36%8%13%4
2280
11th to 20thNight
37%36%7%13%7%
2229
21st to endNight
39%37%8%12%4
2024
April1st to 10thNight
39%37%7%11%6%1
1800
11th to 20thNight
35%37%6%13%8%1
1736
21st to endNight
33%38%7%13%8%2
1620
May1st to 10thNight
34%38%6%12%8%2
1530
11th to 20thNight
33%39%5%15%7%1
1417
21st to endNight
26%40%8%14%10%3
1552
June1st to 10thNight
26%39%7%20%7%2
1440
11th to 20thNight
27%39%9%14%11%1
1360
21st to endNight
28%39%9%15%8%1
1440
July1st to 10thNight
21%38%10%20%10%1
1400
11th to 20thNight
23%41%10%16%10%1
1392
21st to endNight
17%40%12%20%10%1
1487
August1st to 10thNight
23%39%9%20%7%2
1423
11th to 20thNight
17%37%11%22%11%1
1551
21st to endNight
23%37%9%18%11%1
1957
September1st to 10thNight
23%38%9%20%10%
1800
11th to 20thNight
26%38%11%21%4
1903
21st to endNight
30%39%11%16%4
1980
October1st to 10thNight
29%38%10%17%6%1
2037
11th to 20thNight
38%38%9%11%4
2268
21st to endNight
41%40%6%10%2
2574
November1st to 10thNight
33%42%9%10%6%1
2406
11th to 20thNight
41%41%7%6%5%
2512
21st to endNight
39%42%9%9%1
2660
December1st to 10thNight
41%42%9%8%1
2838
11th to 20thNight
46%36%9%7%1
3490
21st to endNight
64%28%441
4884

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 10thDay
19%16%39%24%3
270
11th to 20thDay
18%15%43%20%31
270
21st to endDay
17%13%44%22%4
297
February1st to 10thDay
21%15%41%17%5%
270
11th to 20thDay
14%25%44%15%3
270
21st to endDay
23%22%39%15%
225
March1st to 10thDay
14%24%42%15%5%
270
11th to 20thDay
17%21%38%19%5%1
320
21st to endDay
23%20%31%18%7%
470
April1st to 10thDay
25%14%35%21%41
420
11th to 20thDay
27%15%27%22%8%1
412
21st to endDay
22%17%27%24%7%2
420
May1st to 10thDay
19%17%34%20%7%2
510
11th to 20thDay
19%13%37%23%6%3
625
21st to endDay
15%12%35%26%9%3
679
June1st to 10thDay
13%14%33%28%9%3
630
11th to 20thDay
16%12%34%27%10%2
630
21st to endDay
17%7%32%30%10%3
630
July1st to 10thDay
7%7%32%36%13%5%
621
11th to 20thDay
11%9%31%31%13%3
618
21st to endDay
9%8%33%31%15%5%
684
August1st to 10thDay
11%8%33%33%13%3
626
11th to 20thDay
13%9%23%28%22%5%
486
21st to endDay
19%11%27%25%13%4
495
September1st to 10thDay
18%10%31%23%13%5%
450
11th to 20thDay
13%12%32%28%12%2
450
21st to endDay
23%14%27%25%11%1
450
October1st to 10thDay
27%13%28%22%9%2
392
11th to 20thDay
25%26%36%12%2
270
21st to endDay
32%21%35%9%2
297
November1st to 10thDay
20%21%34%20%4
270
11th to 20thDay
21%27%39%10%3
270
21st to endDay
21%27%32%17%1
270
December1st to 10thDay
19%17%36%21%7%1
183
11th to 20thDay
26%24%35%11%31
186
21st to endDay
24%23%38%12%2
297
January1st to 10thNight
17%20%42%18%3
950
11th to 20thNight
19%19%41%17%41
950
21st to endNight
17%16%38%23%5%1
1045
February1st to 10thNight
16%18%39%21%6%
950
11th to 20thNight
16%18%38%21%6%
791
21st to endNight
19%15%43%18%4
628
March1st to 10thNight
14%14%37%26%8%1
760
11th to 20thNight
17%19%36%23%6%1
760
21st to endNight
21%12%32%25%9%1
624
April1st to 10thNight
24%15%30%24%7%1
540
11th to 20thNight
26%11%28%26%8%1
533
21st to endNight
19%9%31%29%10%1
540
May1st to 10thNight
20%10%24%33%11%2
540
11th to 20thNight
20%10%26%32%10%2
531
21st to endNight
15%7%29%35%13%
584
June1st to 10thNight
14%6%25%38%14%1
540
11th to 20thNight
17%5%26%38%13%
460
21st to endNight
16%6%26%34%13%3
540
July1st to 10thNight
12%325%37%21%2
525
11th to 20thNight
13%431%34%17%1
522
21st to endNight
8%430%37%18%4
591
August1st to 10thNight
11%330%35%19%1
537
11th to 20thNight
10%321%37%25%4
534
21st to endNight
15%7%30%31%16%1
594
September1st to 10thNight
16%5%26%31%19%3
540
11th to 20thNight
16%8%33%32%11%
643
21st to endNight
22%8%28%31%11%1
720
October1st to 10thNight
22%12%32%23%10%2
720
11th to 20thNight
24%16%34%20%7%
720
21st to endNight
30%14%32%18%5%1
792
November1st to 10thNight
22%16%38%20%4
740
11th to 20thNight
23%23%34%16%4
802
21st to endNight
23%19%37%18%3
950
December1st to 10thNight
18%22%40%15%5%1
950
11th to 20thNight
21%18%35%19%6%2
950
21st to endNight
25%19%37%17%3
1045
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