Chanhassen
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chanhassen clear sky chart from 2005-11-05 to 2018-03-21.

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
35%
16953
16%
49149
9%
16906
42%
16906
24%
32957

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%
975
13%
2716
6%
970
35%
970
20%
1951
January16th to endNight
24%
1040
12%
2743
3%
1040
30%
1040
17%
2069
February1st to 15thNight
27%
954
14%
2483
4%
950
33%
950
22%
1785
February16th to endNight
28%
822
16%
2188
5%
822
36%
822
23%
1516
March1st to 15thNight
32%
618
15%
2178
10%
618
39%
618
20%
1442
March16th to endNight
31%
594
15%
2170
13%
594
39%
594
16%
1494
April1st to 15thNight
33%
539
17%
1797
13%
539
42%
539
22%
1185
April16th to endNight
28%
540
16%
1662
9%
540
38%
540
18%
1197
May1st to 15thNight
34%
540
14%
1506
7%
540
39%
540
23%
1044
May16th to endNight
42%
563
15%
1498
6%
561
47%
561
29%
980
June1st to 15thNight
47%
540
13%
1440
5%
540
49%
540
33%
928
June16th to endNight
57%
540
17%
1339
7%
540
60%
540
42%
821
July1st to 15thNight
56%
510
15%
1342
7%
510
59%
510
46%
769
July16th to endNight
61%
564
20%
1447
11%
531
64%
531
45%
816
August1st to 15thNight
63%
539
22%
1610
19%
536
67%
536
36%
927
August16th to endNight
56%
573
23%
1785
20%
573
65%
573
38%
996
September1st to 15thNight
56%
540
23%
1800
22%
540
63%
540
36%
972
September16th to endNight
41%
576
21%
1986
14%
576
52%
576
29%
1145
October1st to 15thNight
37%
720
22%
2160
14%
720
43%
720
30%
1310
October16th to endNight
33%
768
17%
2308
9%
768
41%
768
22%
1563
November1st to 15thNight
31%
908
18%
2619
9%
908
39%
908
24%
1736
November16th to endNight
27%
975
16%
2730
8%
975
35%
975
20%
1944
December1st to 15thNight
24%
975
10%
2730
3%
975
30%
975
16%
2045
December16th to endNight
19%
1040
12%
2912
3%
1040
27%
1040
13%
2322

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%8%36%5%3445%7%37%
49682
Night
12%7%36%5%34446%40%
49320
Cloud CoverDay
26%7%25%423346%32%
49693
Night
24%6%25%423345%36%
49324
Cloud CoverDay
14%8%36%5%3445%7%37%
49691
Night
12%8%36%5%24446%40%
49324
TransparencyDay
46%6%14%22%9%
49371
Night
44%5%13%23%11%1
49149
SeeingDay
17%9%31%26%12%2
6687
Night
15%8%32%30%10%
16954

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%7%9%8%46%445%29%
1552
16th to endDay
9%13%6%9%6%47%5%5%6%24%
1830
February1st to 15thDay
8%11%7%8%6%4445%7%32%
1710
16th to endDay
10%11%5%8%6%36%445%32%
1571
March1st to 15thDay
14%12%46%6%24347%32%
2111
16th to endDay
17%10%37%6%35%436%30%
2180
April1st to 15thDay
16%9%35%5%24346%37%
2151
16th to endDay
23%11%36%423345%29%
2295
May1st to 15thDay
19%8%36%5%3445%5%33%
2445
16th to endDay
16%7%25%43445%7%37%
2617
June1st to 15thDay
16%5%244245%6%8%39%
2520
16th to endDay
9%5%15%6%35%6%6%9%40%
2610
July1st to 15thDay
7%41342446%9%49%
2526
16th to endDay
6%3145%25%47%9%48%
2622
August1st to 15thDay
9%426%5%36%6%6%8%41%
2340
16th to endDay
12%42442435%7%49%
2416
September1st to 15thDay
10%4244345%47%48%
2160
16th to endDay
17%5%25%42346%7%41%
1960
October1st to 15thDay
16%6%26%5%14436%43%
1800
16th to endDay
19%8%35%424436%37%
1914
November1st to 15thDay
12%11%5%5%414346%40%
1568
16th to endDay
14%9%26%5%15%45%9%34%
1560
December1st to 15thDay
14%12%6%9%9%35%445%24%
1560
16th to endDay
18%15%7%11%6%2333423%
1664
January1st to 15thNight
9%9%5%9%7%35%446%34%
2716
16th to endNight
11%12%5%10%6%35%45%6%28%
2743
February1st to 15thNight
8%11%5%8%5%35%346%37%
2480
16th to endNight
9%7%46%6%45%5%47%38%
2188
March1st to 15thNight
13%9%46%5%35%446%38%
2166
16th to endNight
17%9%46%5%24346%35%
2170
April1st to 15thNight
17%8%35%324446%40%
1797
16th to endNight
23%8%35%5%33445%34%
1662
May1st to 15thNight
18%5%35%334447%39%
1506
16th to endNight
11%5%25%5%35%348%43%
1496
June1st to 15thNight
12%43432446%8%45%
1440
16th to endNight
6%22342446%7%54%
1339
July1st to 15thNight
42134245%5%9%55%
1422
16th to endNight
5%12332346%9%56%
1545
August1st to 15thNight
6%3134345%5%7%52%
1620
16th to endNight
8%42332335%5%56%
1785
September1st to 15thNight
8%224423347%56%
1800
16th to endNight
12%424424346%50%
1986
October1st to 15thNight
13%7%24422236%49%
2160
16th to endNight
18%9%25%323345%39%
2308
November1st to 15thNight
15%7%36%423345%42%
2619
16th to endNight
13%10%47%6%34436%36%
2730
December1st to 15thNight
12%11%49%7%34445%31%
2730
16th to endNight
16%14%5%10%7%3345%5%23%
2912

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
21%8%47%8%34435%26%
1552
16th to endDay
23%12%48%6%45%346%20%
1830
February1st to 15thDay
22%9%5%7%5%33345%28%
1710
16th to endDay
23%10%48%5%25%34426%
1571
March1st to 15thDay
27%10%36%5%23245%28%
2122
16th to endDay
29%9%26%5%33335%26%
2180
April1st to 15thDay
29%8%25%423345%31%
2151
16th to endDay
36%10%25%41334423%
2295
May1st to 15thDay
33%7%15%5%2434428%
2445
16th to endDay
31%6%25%323335%31%
2617
June1st to 15thDay
31%5%1332345%6%32%
2520
16th to endDay
25%41442445%7%33%
2610
July1st to 15thDay
23%313323447%41%
2526
16th to endDay
23%31432436%8%38%
2622
August1st to 15thDay
16%4245%246%6%8%38%
2340
16th to endDay
19%314423346%46%
2416
September1st to 15thDay
17%423433446%44%
2160
16th to endDay
22%5%2432345%6%39%
1960
October1st to 15thDay
24%426%413335%40%
1800
16th to endDay
25%8%34423335%36%
1914
November1st to 15thDay
23%10%3431334436%
1568
16th to endDay
28%7%16%422347%31%
1560
December1st to 15thDay
27%10%5%7%8%3442420%
1560
16th to endDay
29%12%6%10%6%2232320%
1664
January1st to 15thNight
21%7%37%6%34335%31%
2716
16th to endNight
24%11%39%5%24345%24%
2743
February1st to 15thNight
22%10%37%5%23235%32%
2473
16th to endNight
21%7%26%5%34445%33%
2188
March1st to 15thNight
25%8%25%423335%34%
2178
16th to endNight
30%7%26%423335%31%
2170
April1st to 15thNight
30%7%25%312335%34%
1797
16th to endNight
37%6%25%42333427%
1662
May1st to 15thNight
33%414223335%33%
1505
16th to endNight
26%5%25%433335%36%
1496
June1st to 15thNight
27%32332335%6%38%
1440
16th to endNight
22%213323245%46%
1339
July1st to 15thNight
20%213324347%46%
1422
16th to endNight
21%11322325%6%47%
1545
August1st to 15thNight
15%313423447%49%
1620
16th to endNight
16%322312345%53%
1785
September1st to 15thNight
15%214423347%51%
1800
16th to endNight
19%323423335%48%
1986
October1st to 15thNight
21%6%23422235%45%
2160
16th to endNight
25%8%15%32234438%
2308
November1st to 15thNight
26%6%25%31333439%
2619
16th to endNight
25%9%36%5%23335%32%
2730
December1st to 15thNight
26%9%38%6%3334426%
2730
16th to endNight
28%11%49%6%2334420%
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
8%11%7%8%9%35%5%36%29%
1552
16th to endDay
10%13%6%9%7%47%45%7%23%
1830
February1st to 15thDay
8%10%7%8%6%345%46%32%
1710
16th to endDay
11%10%5%9%6%26%45%5%31%
1571
March1st to 15thDay
15%12%47%5%2435%6%31%
2122
16th to endDay
17%10%37%6%34436%30%
2178
April1st to 15thDay
16%9%36%5%23346%37%
2151
16th to endDay
23%11%26%5%24345%29%
2295
May1st to 15thDay
20%8%36%5%2435%5%33%
2445
16th to endDay
17%6%35%43445%7%37%
2617
June1st to 15thDay
16%6%244245%6%8%39%
2520
16th to endDay
10%425%5%36%5%6%9%40%
2610
July1st to 15thDay
8%4144245%5%9%49%
2526
16th to endDay
7%324435%47%10%47%
2622
August1st to 15thDay
9%425%5%35%7%6%8%41%
2340
16th to endDay
12%41442435%7%49%
2416
September1st to 15thDay
10%4245%3445%7%47%
2160
16th to endDay
17%5%25%42345%7%41%
1960
October1st to 15thDay
17%6%26%5%23335%43%
1800
16th to endDay
19%9%35%424336%37%
1914
November1st to 15thDay
11%11%5%6%424446%39%
1568
16th to endDay
15%8%27%5%2445%9%34%
1560
December1st to 15thDay
15%11%7%8%9%35%5%35%24%
1560
16th to endDay
18%14%9%10%6%2333423%
1664
January1st to 15thNight
9%9%5%9%7%35%45%6%34%
2716
16th to endNight
11%12%5%10%6%35%45%6%28%
2743
February1st to 15thNight
8%11%5%8%6%35%346%37%
2473
16th to endNight
9%8%36%6%45%5%5%6%38%
2188
March1st to 15thNight
13%9%36%5%24446%38%
2178
16th to endNight
17%9%47%5%34346%34%
2170
April1st to 15thNight
17%8%36%313446%39%
1797
16th to endNight
23%8%35%5%23445%34%
1662
May1st to 15thNight
19%5%35%334446%39%
1505
16th to endNight
11%5%26%5%35%45%7%43%
1496
June1st to 15thNight
12%43442346%7%45%
1440
16th to endNight
6%21432436%7%54%
1339
July1st to 15thNight
4213435%45%9%55%
1422
16th to endNight
6%12332446%8%56%
1545
August1st to 15thNight
7%323425%5%5%7%53%
1620
16th to endNight
9%33332345%6%55%
1785
September1st to 15thNight
8%324423348%55%
1800
16th to endNight
12%424423446%50%
1986
October1st to 15thNight
13%7%33422246%49%
2160
16th to endNight
18%9%35%323345%40%
2308
November1st to 15thNight
15%7%36%424445%42%
2619
16th to endNight
13%10%37%6%34336%36%
2730
December1st to 15thNight
12%11%49%8%35%34431%
2730
16th to endNight
16%14%6%10%7%3445%423%
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
56%5%12%18%7%
1553
16th to endDay
58%7%13%16%4
1830
February1st to 15thDay
52%5%15%18%7%
1711
16th to endDay
52%7%11%21%6%
1571
March1st to 15thDay
52%5%14%19%6%
2122
16th to endDay
54%6%12%21%4
2180
April1st to 15thDay
48%412%22%10%1
2151
16th to endDay
57%413%16%7%1
2295
May1st to 15thDay
51%6%12%21%7%
2445
16th to endDay
45%7%12%21%11%1
2621
June1st to 15thDay
40%6%15%26%9%
2520
16th to endDay
37%8%16%26%10%1
2610
July1st to 15thDay
30%7%17%28%14%1
2377
16th to endDay
31%8%18%23%17%1
2457
August1st to 15thDay
38%8%13%27%9%2
2326
16th to endDay
33%6%16%28%13%1
2416
September1st to 15thDay
35%5%15%30%11%
2160
16th to endDay
41%6%14%30%7%
1960
October1st to 15thDay
43%312%26%12%
1800
16th to endDay
48%414%23%7%
1914
November1st to 15thDay
44%5%14%21%13%1
1568
16th to endDay
47%6%20%17%7%
1560
December1st to 15thDay
60%7%14%11%5%
1560
16th to endDay
65%310%13%6%
1664
January1st to 15thNight
50%5%13%21%8%
2716
16th to endNight
55%415%16%5%
2743
February1st to 15thNight
49%414%22%9%
2483
16th to endNight
45%6%13%23%10%
2188
March1st to 15thNight
46%5%14%22%10%
2178
16th to endNight
51%5%12%23%6%
2170
April1st to 15thNight
45%49%24%13%1
1797
16th to endNight
52%5%9%16%12%2
1662
May1st to 15thNight
45%6%14%18%12%2
1506
16th to endNight
38%6%13%23%16%2
1498
June1st to 15thNight
35%6%15%27%13%1
1440
16th to endNight
28%6%14%28%18%3
1339
July1st to 15thNight
24%6%15%32%18%2
1342
16th to endNight
23%7%16%30%17%4
1447
August1st to 15thNight
28%7%12%30%17%3
1610
16th to endNight
28%5%16%27%18%3
1785
September1st to 15thNight
28%5%14%31%19%
1800
16th to endNight
35%414%29%15%
1986
October1st to 15thNight
37%312%28%15%2
2160
16th to endNight
46%5%14%20%13%1
2308
November1st to 15thNight
43%5%13%22%14%1
2619
16th to endNight
49%5%15%19%8%
2730
December1st to 15thNight
55%6%13%19%5%
2730
16th to endNight
63%5%12%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
16%9%36%28%8%
135
16th to endDay
20%9%38%25%6%
144
February1st to 15thDay
11%17%43%24%3
135
16th to endDay
20%19%33%20%5%
120
March1st to 15thDay
20%14%41%20%3
135
16th to endDay
25%14%28%22%7%2
120
April1st to 15thDay
18%11%36%21%11%
270
16th to endDay
30%10%32%17%8%
405
May1st to 15thDay
23%14%31%21%7%1
468
16th to endDay
20%10%28%26%11%2
517
June1st to 15thDay
16%7%31%29%13%2
495
16th to endDay
10%9%34%27%14%3
495
July1st to 15thDay
9%5%28%31%17%7%
475
16th to endDay
7%5%28%35%19%3
515
August1st to 15thDay
11%225%34%22%3
493
16th to endDay
16%424%32%16%6%
456
September1st to 15thDay
12%6%25%33%18%4
315
16th to endDay
25%6%30%22%11%3
166
October1st to 15thDay
14%13%36%22%11%2
135
16th to endDay
24%11%34%18%11%
144
November1st to 15thDay
14%11%39%22%10%1
135
16th to endDay
28%12%44%12%2
135
December1st to 15thDay
18%17%36%25%2
135
16th to endDay
29%16%40%11%1
144
January1st to 15thNight
12%13%36%29%7%1
975
16th to endNight
17%10%39%28%4
1040
February1st to 15thNight
14%10%36%30%7%
955
16th to endNight
12%12%40%24%8%
822
March1st to 15thNight
15%9%36%28%8%
618
16th to endNight
18%10%31%24%13%1
594
April1st to 15thNight
20%9%33%28%7%
539
16th to endNight
27%5%33%26%6%
540
May1st to 15thNight
21%8%32%30%6%
540
16th to endNight
13%7%30%31%15%
563
June1st to 15thNight
13%5%28%42%10%
540
16th to endNight
8%327%47%12%
540
July1st to 15thNight
5%131%37%21%1
510
16th to endNight
6%125%47%17%1
564
August1st to 15thNight
8%120%43%23%2
539
16th to endNight
9%324%35%24%2
573
September1st to 15thNight
10%323%38%19%4
540
16th to endNight
12%8%33%26%17%1
576
October1st to 15thNight
17%10%31%26%13%1
720
16th to endNight
23%10%27%29%9%
768
November1st to 15thNight
19%10%32%27%8%
908
16th to endNight
17%15%35%24%7%
975
December1st to 15thNight
18%9%40%26%5%
975
16th to endNight
23%11%32%26%5%
1040
Page generated at 2018-03-22 10:34:27. Version ac04

Copyright 2018 A. Danko


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