Burnsville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burnsville clear sky chart from 2005-11-05 to 2017-08-12.

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%
16009
16%
46529
8%
15963
42%
15963
24%
31287

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
27%
900
13%
2506
6%
895
34%
895
18%
1837
January16th to endNight
22%
960
12%
2541
4%
960
29%
960
17%
1924
February1st to 15thNight
26%
879
13%
2288
4%
875
32%
875
22%
1651
February16th to endNight
28%
751
16%
2013
5%
751
36%
751
23%
1403
March1st to 15thNight
32%
579
14%
2019
10%
579
38%
579
19%
1342
March16th to endNight
31%
576
14%
2097
11%
576
39%
576
16%
1437
April1st to 15thNight
33%
539
17%
1797
12%
539
42%
539
21%
1185
April16th to endNight
29%
540
16%
1674
10%
540
38%
540
17%
1201
May1st to 15thNight
32%
540
14%
1500
7%
540
37%
540
23%
1045
May16th to endNight
41%
562
15%
1498
6%
561
47%
561
29%
981
June1st to 15thNight
45%
540
13%
1440
5%
540
48%
540
33%
930
June16th to endNight
56%
540
16%
1440
7%
540
59%
540
40%
867
July1st to 15thNight
58%
510
15%
1360
6%
510
61%
510
45%
779
July16th to endNight
61%
564
20%
1439
11%
531
64%
531
46%
818
August1st to 15thNight
63%
527
22%
1575
18%
524
67%
524
37%
900
August16th to endNight
56%
525
21%
1644
19%
525
63%
525
36%
923
September1st to 15thNight
56%
495
24%
1650
22%
495
65%
495
34%
911
September16th to endNight
40%
533
19%
1816
12%
533
49%
533
29%
1054
October1st to 15thNight
37%
660
23%
1980
15%
660
44%
660
30%
1204
October16th to endNight
32%
704
16%
2123
9%
704
39%
704
21%
1435
November1st to 15thNight
30%
825
20%
2401
9%
825
39%
825
25%
1572
November16th to endNight
27%
900
14%
2520
7%
900
32%
900
19%
1843
December1st to 15thNight
23%
900
10%
2520
3%
900
29%
900
15%
1893
December16th to endNight
20%
960
11%
2688
3%
960
28%
960
12%
2152

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%36%5%3445%7%37%
47453
Night
13%7%36%5%34446%40%
46700
Cloud CoverDay
25%6%25%433346%32%
47464
Night
25%6%25%423345%35%
46704
Cloud CoverDay
13%8%36%5%35%45%7%36%
47462
Night
12%7%36%5%34446%40%
46704
TransparencyDay
45%6%14%22%9%
47142
Night
44%5%13%23%11%1
46529
SeeingDay
16%9%30%27%13%2
5970
Night
16%8%32%30%10%1
16011

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%45%436%28%
1432
16th to endDay
10%13%6%10%7%36%5%6%6%22%
1683
February1st to 15thDay
8%12%7%9%7%4445%5%30%
1575
16th to endDay
13%9%5%7%5%35%5%5%6%31%
1459
March1st to 15thDay
15%11%47%5%25%446%32%
1940
16th to endDay
19%9%36%6%34437%30%
2126
April1st to 15thDay
17%9%45%434346%37%
2151
16th to endDay
23%11%36%433445%29%
2284
May1st to 15thDay
20%7%35%6%245%46%33%
2451
16th to endDay
16%6%35%434448%38%
2617
June1st to 15thDay
17%4244245%5%8%40%
2520
16th to endDay
10%4245%46%5%6%8%40%
2520
July1st to 15thDay
7%32443446%10%48%
2520
16th to endDay
7%324435%5%6%9%47%
2629
August1st to 15thDay
10%425%6%35%6%5%8%41%
2289
16th to endDay
11%32442345%8%49%
2206
September1st to 15thDay
12%5%25%3245%47%46%
1980
16th to endDay
15%5%25%42445%7%42%
1802
October1st to 15thDay
16%5%25%423345%45%
1650
16th to endDay
19%9%25%42334438%
1749
November1st to 15thDay
11%9%5%6%5%1335%6%40%
1454
16th to endDay
15%9%38%424347%35%
1440
December1st to 15thDay
16%11%6%8%7%35%45%5%26%
1440
16th to endDay
19%14%6%11%6%3332422%
1536
January1st to 15thNight
10%9%6%7%6%45%45%6%33%
2506
16th to endNight
12%12%5%9%5%35%5%5%5%28%
2541
February1st to 15thNight
9%11%5%8%7%34335%36%
2285
16th to endNight
8%8%47%6%35%5%46%38%
2013
March1st to 15thNight
12%8%46%5%24347%38%
2007
16th to endNight
18%9%37%42435%5%35%
2097
April1st to 15thNight
17%8%35%424446%39%
1797
16th to endNight
25%6%34424445%33%
1674
May1st to 15thNight
19%5%35%423446%40%
1500
16th to endNight
12%425%5%34448%43%
1496
June1st to 15thNight
12%325%43445%8%45%
1440
16th to endNight
7%313435%45%7%54%
1440
July1st to 15thNight
42234235%5%9%56%
1440
16th to endNight
6%213335%448%57%
1537
August1st to 15thNight
6%3244345%5%7%52%
1585
16th to endNight
9%413323446%55%
1644
September1st to 15thNight
10%32332335%5%54%
1650
16th to endNight
12%4345%23345%50%
1816
October1st to 15thNight
14%5%24423335%50%
1980
16th to endNight
20%7%34423345%40%
2123
November1st to 15thNight
13%8%25%434445%43%
2401
16th to endNight
14%10%47%5%34436%34%
2520
December1st to 15thNight
13%10%49%7%45%445%30%
2520
16th to endNight
18%14%6%9%6%34445%23%
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%7%44335%25%
1432
16th to endDay
24%12%49%5%35%446%18%
1683
February1st to 15thDay
23%11%47%6%3433426%
1575
16th to endDay
26%7%47%5%34445%26%
1459
March1st to 15thDay
28%8%37%423345%28%
1951
16th to endDay
31%7%26%5%43335%26%
2126
April1st to 15thDay
30%7%3442333431%
2151
16th to endDay
35%10%35%42233422%
2284
May1st to 15thDay
31%6%25%5%34435%26%
2451
16th to endDay
29%6%25%423346%30%
2617
June1st to 15thDay
30%424413446%32%
2520
16th to endDay
25%42444446%7%31%
2520
July1st to 15thDay
22%31342336%9%38%
2520
16th to endDay
21%31443445%7%38%
2629
August1st to 15thDay
16%3145%446%6%8%37%
2289
16th to endDay
17%324323347%45%
2206
September1st to 15thDay
18%5%14435%345%43%
1980
16th to endDay
21%5%2432445%6%39%
1802
October1st to 15thDay
22%5%25%42234442%
1650
16th to endDay
25%7%25%423245%35%
1749
November1st to 15thDay
22%8%35%5%13345%36%
1454
16th to endDay
30%6%36%432245%31%
1440
December1st to 15thDay
30%9%47%5%3444321%
1440
16th to endDay
30%13%411%6%3213319%
1536
January1st to 15thNight
23%7%37%6%34435%29%
2506
16th to endNight
26%11%47%5%3444423%
2541
February1st to 15thNight
23%10%37%5%23335%32%
2278
16th to endNight
22%7%26%6%34445%32%
2013
March1st to 15thNight
25%7%35%5%23236%34%
2019
16th to endNight
30%7%25%42333431%
2097
April1st to 15thNight
30%6%25%32334434%
1797
16th to endNight
37%6%2442433426%
1674
May1st to 15thNight
33%5%14323335%33%
1499
16th to endNight
26%425%5%23246%35%
1496
June1st to 15thNight
26%414432346%37%
1440
16th to endNight
23%213323345%45%
1440
July1st to 15thNight
20%113323447%47%
1440
16th to endNight
20%213324338%46%
1537
August1st to 15thNight
14%21432346%7%48%
1585
16th to endNight
17%313222435%52%
1644
September1st to 15thNight
17%312423345%49%
1650
16th to endNight
18%424423335%47%
1816
October1st to 15thNight
21%6%24312335%45%
1980
16th to endNight
26%7%24322345%37%
2123
November1st to 15thNight
24%6%2442333439%
2401
16th to endNight
27%9%36%43433429%
2520
December1st to 15thNight
28%8%37%6%3333425%
2520
16th to endNight
30%12%48%5%3333420%
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%12%6%9%8%5%6%345%28%
1432
16th to endDay
9%14%6%10%7%37%5%47%21%
1683
February1st to 15thDay
9%12%6%8%7%45%345%30%
1575
16th to endDay
13%8%5%8%5%35%5%5%6%31%
1459
March1st to 15thDay
15%11%5%7%5%24446%32%
1951
16th to endDay
19%9%36%5%34446%31%
2124
April1st to 15thDay
17%9%35%5%24346%36%
2151
16th to endDay
22%11%35%5%34445%29%
2284
May1st to 15thDay
19%7%35%6%34447%32%
2451
16th to endDay
14%7%35%5%25%45%8%37%
2617
June1st to 15thDay
15%5%2442446%9%39%
2520
16th to endDay
9%325%5%47%5%7%8%39%
2520
July1st to 15thDay
7%32442447%10%47%
2520
16th to endDay
6%4235%35%6%6%9%46%
2629
August1st to 15thDay
9%4245%45%6%7%8%40%
2289
16th to endDay
10%325%42436%8%48%
2206
September1st to 15thDay
11%5%14435%445%46%
1980
16th to endDay
14%7%25%42345%7%41%
1802
October1st to 15thDay
15%6%245%23445%45%
1650
16th to endDay
18%8%35%5%34345%37%
1749
November1st to 15thDay
9%10%5%6%5%2435%6%39%
1454
16th to endDay
15%9%27%5%34348%34%
1440
December1st to 15thDay
16%11%6%8%7%35%5%5%425%
1440
16th to endDay
18%14%7%10%7%3422422%
1536
January1st to 15thNight
10%9%5%7%6%46%45%6%32%
2506
16th to endNight
11%12%6%9%6%35%5%5%6%29%
2541
February1st to 15thNight
8%10%5%9%6%35%335%37%
2278
16th to endNight
9%7%47%6%45%45%6%38%
2013
March1st to 15thNight
12%9%46%6%34347%38%
2019
16th to endNight
17%9%46%434346%35%
2097
April1st to 15thNight
17%9%35%323346%39%
1797
16th to endNight
24%8%25%434446%32%
1674
May1st to 15thNight
19%7%25%42345%6%39%
1499
16th to endNight
11%5%35%5%3445%7%42%
1496
June1st to 15thNight
12%425%42445%8%44%
1440
16th to endNight
7%2235%2345%7%53%
1440
July1st to 15thNight
3215%32446%9%56%
1440
16th to endNight
5%31343445%9%55%
1537
August1st to 15thNight
6%3144246%5%8%52%
1585
16th to endNight
9%424323346%54%
1644
September1st to 15thNight
9%3135%23346%54%
1650
16th to endNight
12%5%25%423346%49%
1816
October1st to 15thNight
14%6%25%323336%49%
1980
16th to endNight
19%8%25%433336%39%
2123
November1st to 15thNight
13%8%345%24345%44%
2401
16th to endNight
14%10%48%5%35%446%33%
2520
December1st to 15thNight
13%10%49%8%45%345%30%
2520
16th to endNight
18%14%5%9%7%34445%22%
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
57%6%11%17%7%
1433
16th to endDay
60%6%13%15%3
1683
February1st to 15thDay
54%5%14%18%6%
1576
16th to endDay
52%6%13%22%5%
1459
March1st to 15thDay
51%6%15%19%6%
1951
16th to endDay
54%6%12%21%3
2126
April1st to 15thDay
48%413%21%10%1
2151
16th to endDay
56%5%13%16%7%1
2284
May1st to 15thDay
51%6%12%21%6%
2451
16th to endDay
45%7%12%21%11%1
2621
June1st to 15thDay
40%7%15%26%9%
2520
16th to endDay
37%8%17%24%10%1
2520
July1st to 15thDay
30%8%16%28%14%1
2371
16th to endDay
30%9%18%23%15%1
2464
August1st to 15thDay
36%9%13%28%9%2
2275
16th to endDay
32%6%17%27%14%1
2206
September1st to 15thDay
36%6%14%28%12%
1980
16th to endDay
41%6%14%29%8%
1802
October1st to 15thDay
40%412%28%13%
1650
16th to endDay
48%5%14%22%7%
1749
November1st to 15thDay
44%5%13%21%13%1
1454
16th to endDay
49%6%19%16%6%
1440
December1st to 15thDay
59%7%14%12%5%
1440
16th to endDay
67%410%13%4
1536
January1st to 15thNight
51%6%12%21%6%
2506
16th to endNight
56%415%17%5%
2541
February1st to 15thNight
49%414%21%8%
2288
16th to endNight
46%5%13%24%9%
2013
March1st to 15thNight
46%5%14%22%10%
2019
16th to endNight
50%5%13%23%5%
2097
April1st to 15thNight
46%49%24%13%1
1797
16th to endNight
52%5%9%17%12%2
1674
May1st to 15thNight
45%6%14%18%12%2
1500
16th to endNight
39%6%13%23%16%1
1498
June1st to 15thNight
36%6%15%27%13%1
1440
16th to endNight
28%6%14%28%18%3
1440
July1st to 15thNight
24%6%15%32%18%2
1360
16th to endNight
24%5%16%30%17%4
1439
August1st to 15thNight
29%6%13%29%17%3
1575
16th to endNight
28%6%15%27%18%3
1644
September1st to 15thNight
30%5%13%29%20%
1650
16th to endNight
35%414%29%14%
1816
October1st to 15thNight
37%411%28%15%3
1980
16th to endNight
46%5%13%21%12%
2123
November1st to 15thNight
42%5%13%22%15%1
2401
16th to endNight
52%5%15%17%8%
2520
December1st to 15thNight
55%6%13%18%5%
2520
16th to endNight
63%5%12%13%5%
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
17%12%35%25%7%1
90
16th to endDay
21%10%40%22%4
96
February1st to 15thDay
13%20%42%20%4
90
16th to endDay
22%14%29%28%31
81
March1st to 15thDay
18%14%42%22%2
90
16th to endDay
30%14%30%19%6%
110
April1st to 15thDay
19%11%34%23%10%
270
16th to endDay
31%10%31%19%7%1
394
May1st to 15thDay
21%16%30%22%7%1
468
16th to endDay
18%11%29%25%12%2
517
June1st to 15thDay
14%8%30%31%13%1
495
16th to endDay
11%9%34%26%14%2
495
July1st to 15thDay
8%5%28%30%18%7%
475
16th to endDay
7%5%28%33%21%3
515
August1st to 15thDay
9%325%36%20%4
474
16th to endDay
13%5%25%33%17%4
374
September1st to 15thDay
13%8%22%33%16%6%
255
16th to endDay
23%10%24%23%13%4
129
October1st to 15thDay
7%11%33%30%13%4
90
16th to endDay
27%10%33%19%9%
96
November1st to 15thDay
5%5%42%31%13%2
90
16th to endDay
40%8%38%10%2
90
December1st to 15thDay
18%15%30%33%2
90
16th to endDay
36%16%36%9%1
96
January1st to 15thNight
14%12%36%28%7%1
900
16th to endNight
17%11%39%27%4
960
February1st to 15thNight
14%10%37%29%6%1
880
16th to endNight
13%11%39%25%9%
751
March1st to 15thNight
15%9%36%29%8%
579
16th to endNight
19%10%31%25%11%1
576
April1st to 15thNight
20%10%32%28%7%
539
16th to endNight
27%6%31%25%6%
540
May1st to 15thNight
21%9%32%29%6%
540
16th to endNight
13%7%31%31%15%
563
June1st to 15thNight
13%5%30%40%9%
540
16th to endNight
8%228%47%12%
540
July1st to 15thNight
5%229%38%23%1
510
16th to endNight
5%225%47%17%1
564
August1st to 15thNight
7%122%43%22%2
527
16th to endNight
9%226%34%24%2
525
September1st to 15thNight
10%424%37%18%4
495
16th to endNight
12%9%33%25%18%1
533
October1st to 15thNight
18%10%30%25%13%1
660
16th to endNight
23%9%27%29%9%
704
November1st to 15thNight
18%11%33%26%8%
825
16th to endNight
18%14%34%24%8%
900
December1st to 15thNight
19%10%39%25%5%
900
16th to endNight
25%10%30%27%5%
960
Page generated at 2017-08-13 13:16:42. Version ac04

Copyright 2017 A. Danko


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