This page made possible by the sponsorship of: Chippewa Valley Astronomical Society.

Hobbs Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hobbs Observatory clear sky chart from 2005-11-05 to 2017-05-24.

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%
15773
16%
45878
9%
15726
42%
15726
23%
30860

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
26%
900
12%
2506
6%
895
32%
895
18%
1858
January16th to endNight
23%
960
12%
2612
4%
960
29%
960
16%
2001
February1st to 15thNight
29%
880
15%
2288
5%
876
35%
876
22%
1636
February16th to endNight
29%
693
15%
1955
6%
693
35%
693
19%
1378
March1st to 15thNight
34%
651
16%
2091
11%
651
39%
651
21%
1363
March16th to endNight
34%
576
17%
2046
14%
576
41%
576
18%
1360
April1st to 15thNight
29%
539
16%
1797
12%
539
38%
539
20%
1192
April16th to endNight
31%
540
17%
1742
11%
540
39%
540
19%
1205
May1st to 15thNight
30%
540
15%
1440
8%
540
36%
540
23%
1034
May16th to endNight
43%
542
15%
1441
6%
540
49%
540
30%
958
June1st to 15thNight
45%
495
12%
1320
5%
495
48%
495
28%
890
June16th to endNight
53%
495
15%
1320
6%
495
57%
495
39%
792
July1st to 15thNight
56%
465
18%
1240
9%
465
60%
465
44%
706
July16th to endNight
67%
522
18%
1305
10%
489
69%
489
46%
738
August1st to 15thNight
66%
494
24%
1418
20%
491
68%
491
38%
829
August16th to endNight
53%
525
21%
1696
19%
525
59%
525
33%
958
September1st to 15thNight
57%
495
25%
1650
23%
495
65%
495
34%
904
September16th to endNight
48%
580
20%
1789
15%
580
55%
580
32%
1045
October1st to 15thNight
42%
660
24%
1980
17%
660
48%
660
31%
1188
October16th to endNight
35%
704
16%
2181
10%
704
42%
704
22%
1457
November1st to 15thNight
32%
757
20%
2333
12%
757
41%
757
25%
1497
November16th to endNight
26%
900
14%
2520
8%
900
33%
900
19%
1810
December1st to 15thNight
21%
900
10%
2520
3%
900
27%
900
16%
1900
December16th to endNight
20%
960
11%
2688
4%
960
27%
960
12%
2161

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
15%8%36%5%3445%6%35%
46408
Night
14%8%36%5%24446%38%
46047
Cloud CoverDay
27%7%25%423345%31%
46418
Night
26%7%25%423345%33%
46051
Cloud CoverDay
15%8%36%5%3445%7%35%
46416
Night
14%8%36%5%24446%38%
46051
TransparencyDay
48%313%23%9%
46093
Night
46%312%24%11%1
45879
SeeingDay
18%7%26%27%14%4
5580
Night
18%7%29%31%11%1
15773

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
12%11%6%9%6%36%35%6%27%
1432
16th to endDay
13%15%5%11%6%35%45%7%20%
1611
February1st to 15thDay
10%10%6%9%5%35%45%6%32%
1575
16th to endDay
14%10%5%8%5%35%5%5%6%29%
1517
March1st to 15thDay
15%10%46%5%25%445%34%
1868
16th to endDay
19%9%36%5%3435%6%32%
2178
April1st to 15thDay
17%10%46%6%2435%5%34%
2151
16th to endDay
24%10%26%5%24345%30%
2217
May1st to 15thDay
19%7%36%6%35%446%32%
2511
16th to endDay
14%6%25%6%2446%6%38%
2516
June1st to 15thDay
20%5%35%42445%7%36%
2310
16th to endDay
10%5%25%5%36%6%6%9%38%
2310
July1st to 15thDay
8%324436%5%6%9%44%
2310
16th to endDay
9%3245%35%6%6%9%43%
2459
August1st to 15thDay
10%5%346%35%5%7%9%39%
2202
16th to endDay
13%5%2442446%8%43%
2154
September1st to 15thDay
13%425%42345%7%45%
1980
16th to endDay
17%5%245%34347%40%
1829
October1st to 15thDay
16%7%35%324346%42%
1650
16th to endDay
21%10%26%423235%37%
1690
November1st to 15thDay
15%9%45%423336%39%
1522
16th to endDay
17%11%446%2436%5%31%
1440
December1st to 15thDay
16%11%6%9%9%45%43423%
1440
16th to endDay
20%16%6%11%8%4332319%
1536
January1st to 15thNight
13%10%6%9%6%35%345%31%
2506
16th to endNight
12%13%6%9%7%345%5%6%25%
2612
February1st to 15thNight
8%11%5%8%6%25%446%35%
2285
16th to endNight
11%11%5%7%6%345%45%34%
1955
March1st to 15thNight
12%7%46%5%24446%41%
2079
16th to endNight
18%8%35%5%23346%36%
2046
April1st to 15thNight
21%8%2442445%5%36%
1797
16th to endNight
23%8%35%433347%33%
1742
May1st to 15thNight
23%5%25%5%24446%34%
1440
16th to endNight
13%5%36%42445%6%43%
1440
June1st to 15thNight
15%5%25%5%345%5%8%38%
1320
16th to endNight
9%324325%5%6%9%47%
1320
July1st to 15thNight
7%21332345%9%54%
1320
16th to endNight
6%22435%5%5%9%53%
1401
August1st to 15thNight
8%32442446%8%50%
1427
16th to endNight
14%424314345%51%
1696
September1st to 15thNight
10%41442345%6%52%
1650
16th to endNight
13%5%14423436%49%
1789
October1st to 15thNight
16%6%23322236%48%
1980
16th to endNight
19%8%25%423345%39%
2181
November1st to 15thNight
14%9%35%32345%7%40%
2333
16th to endNight
17%9%47%5%34446%32%
2520
December1st to 15thNight
15%13%6%8%7%24346%28%
2520
16th to endNight
19%15%5%11%7%2433423%
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
25%8%5%7%5%35%346%24%
1432
16th to endDay
27%14%311%5%3335%5%16%
1611
February1st to 15thDay
24%10%48%433245%28%
1575
16th to endDay
26%8%47%5%33445%24%
1517
March1st to 15thDay
28%8%35%42433432%
1878
16th to endDay
31%8%25%5%24335%27%
2178
April1st to 15thDay
30%8%25%5%2334429%
2151
16th to endDay
37%9%25%41333424%
2217
May1st to 15thDay
32%5%26%5%24345%27%
2511
16th to endDay
29%5%24423445%32%
2516
June1st to 15thDay
35%5%24323445%28%
2310
16th to endDay
27%4244345%47%31%
2310
July1st to 15thDay
26%21433445%7%35%
2310
16th to endDay
26%3133335%5%7%35%
2459
August1st to 15thDay
18%4245%3447%8%36%
2202
16th to endDay
19%5%1342345%7%41%
2154
September1st to 15thDay
20%5%1442335%6%41%
1980
16th to endDay
23%424434346%37%
1829
October1st to 15thDay
24%6%24314335%40%
1650
16th to endDay
28%9%25%41223435%
1690
November1st to 15thDay
27%7%34422235%35%
1522
16th to endDay
30%8%335%2425%429%
1440
December1st to 15thDay
29%11%47%6%3433320%
1440
16th to endDay
32%13%49%7%2232317%
1536
January1st to 15thNight
25%8%48%5%3434428%
2506
16th to endNight
27%11%48%5%2344421%
2612
February1st to 15thNight
22%9%5%7%5%13345%30%
2278
16th to endNight
23%9%36%5%3343430%
1955
March1st to 15thNight
25%6%25%423335%36%
2091
16th to endNight
31%7%25%422245%31%
2046
April1st to 15thNight
33%7%1442334431%
1797
16th to endNight
37%7%24322235%26%
1742
May1st to 15thNight
36%5%24423336%27%
1439
16th to endNight
29%5%24313345%35%
1440
June1st to 15thNight
31%3244335%5%6%29%
1320
16th to endNight
26%213314347%40%
1320
July1st to 15thNight
24%213322347%44%
1320
16th to endNight
23%12223447%45%
1401
August1st to 15thNight
15%31342445%7%46%
1427
16th to endNight
20%313313245%49%
1696
September1st to 15thNight
16%42432335%5%48%
1650
16th to endNight
19%414323336%47%
1789
October1st to 15thNight
23%5%23322235%45%
1980
16th to endNight
27%7%2432334436%
2181
November1st to 15thNight
25%8%34312336%37%
2333
16th to endNight
29%8%36%423435%28%
2520
December1st to 15thNight
30%12%47%6%2223423%
2520
16th to endNight
31%12%49%6%2323320%
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
12%10%6%9%7%36%45%6%27%
1432
16th to endDay
13%16%5%11%7%35%45%6%20%
1611
February1st to 15thDay
10%11%6%8%6%35%45%6%32%
1575
16th to endDay
14%10%49%6%35%5%5%7%28%
1517
March1st to 15thDay
16%9%46%5%25%446%34%
1878
16th to endDay
19%9%36%5%2435%6%32%
2176
April1st to 15thDay
17%9%37%6%34345%34%
2151
16th to endDay
24%10%35%5%24345%30%
2217
May1st to 15thDay
19%7%36%6%35%45%6%32%
2511
16th to endDay
14%6%25%6%345%6%7%38%
2516
June1st to 15thDay
20%5%35%42445%8%35%
2310
16th to endDay
9%5%25%6%36%6%6%10%37%
2310
July1st to 15thDay
8%4145%36%5%7%9%43%
2310
16th to endDay
8%4245%36%5%6%10%42%
2459
August1st to 15thDay
9%5%25%5%35%5%8%8%39%
2202
16th to endDay
13%6%1442445%8%42%
2154
September1st to 15thDay
12%5%25%5%2345%7%45%
1980
16th to endDay
17%434444347%39%
1829
October1st to 15thDay
16%7%35%323446%42%
1650
16th to endDay
21%10%35%423235%36%
1690
November1st to 15thDay
15%9%45%433336%39%
1522
16th to endDay
17%11%35%6%25%36%6%31%
1440
December1st to 15thDay
15%12%6%10%9%45%43423%
1440
16th to endDay
19%16%6%11%8%3433319%
1536
January1st to 15thNight
12%11%5%9%6%35%445%30%
2506
16th to endNight
12%13%6%9%7%346%5%6%25%
2612
February1st to 15thNight
8%11%6%8%6%35%445%35%
2278
16th to endNight
11%11%5%6%6%34445%34%
1955
March1st to 15thNight
13%7%36%5%34445%41%
2091
16th to endNight
18%8%35%5%23345%36%
2046
April1st to 15thNight
21%8%2442445%5%36%
1797
16th to endNight
23%8%25%423346%33%
1742
May1st to 15thNight
22%6%26%425%445%34%
1439
16th to endNight
14%5%35%424446%43%
1440
June1st to 15thNight
15%5%25%5%435%5%8%39%
1320
16th to endNight
9%324325%5%7%8%48%
1320
July1st to 15thNight
7%31422345%9%55%
1320
16th to endNight
6%23335%5%5%9%53%
1401
August1st to 15thNight
8%4144245%5%8%49%
1427
16th to endNight
14%424314345%51%
1696
September1st to 15thNight
10%42442335%6%52%
1650
16th to endNight
13%424423447%49%
1789
October1st to 15thNight
16%5%24323237%48%
1980
16th to endNight
19%9%35%42334439%
2181
November1st to 15thNight
14%9%45%413447%40%
2333
16th to endNight
17%10%47%5%34446%32%
2520
December1st to 15thNight
15%14%5%8%7%24345%28%
2520
16th to endNight
19%15%5%11%6%2433422%
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%411%20%6%
1433
16th to endDay
62%313%14%5%
1611
February1st to 15thDay
52%216%19%7%1
1576
16th to endDay
53%5%10%23%7%
1517
March1st to 15thDay
51%315%20%8%
1878
16th to endDay
53%314%23%5%
2178
April1st to 15thDay
52%210%20%12%1
2151
16th to endDay
57%211%17%9%
2217
May1st to 15thDay
52%313%21%7%
2511
16th to endDay
44%5%11%24%12%2
2520
June1st to 15thDay
46%313%27%8%
2310
16th to endDay
40%415%26%12%1
2310
July1st to 15thDay
35%413%29%13%2
2161
16th to endDay
34%5%17%27%13%1
2292
August1st to 15thDay
38%5%12%29%12%1
2187
16th to endDay
37%414%29%13%1
2154
September1st to 15thDay
37%413%31%13%
1980
16th to endDay
44%314%30%7%
1829
October1st to 15thDay
42%313%28%12%
1650
16th to endDay
51%212%25%7%
1690
November1st to 15thDay
46%311%23%12%1
1522
16th to endDay
52%418%18%5%
1440
December1st to 15thDay
64%212%16%4
1440
16th to endDay
70%210%11%4
1536
January1st to 15thNight
55%312%21%6%
2506
16th to endNight
58%412%18%5%
2612
February1st to 15thNight
49%312%23%8%1
2288
16th to endNight
50%312%24%7%
1955
March1st to 15thNight
45%412%25%10%1
2091
16th to endNight
49%311%25%8%1
2046
April1st to 15thNight
49%38%22%15%2
1797
16th to endNight
52%28%21%13%2
1742
May1st to 15thNight
50%411%21%12%1
1440
16th to endNight
41%410%23%18%1
1442
June1st to 15thNight
42%5%12%28%11%
1320
16th to endNight
31%415%29%16%2
1320
July1st to 15thNight
26%412%34%19%1
1240
16th to endNight
25%418%29%18%3
1305
August1st to 15thNight
31%412%28%20%2
1418
16th to endNight
34%214%28%16%3
1696
September1st to 15thNight
31%311%31%20%
1650
16th to endNight
35%313%34%12%
1789
October1st to 15thNight
38%110%32%14%1
1980
16th to endNight
48%213%22%12%
2181
November1st to 15thNight
43%313%24%14%1
2333
16th to endNight
52%315%19%7%
2520
December1st to 15thNight
58%313%19%4
2520
16th to endNight
66%310%14%4
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
23%10%34%24%6%1
90
16th to endDay
28%11%29%26%5%
96
February1st to 15thDay
14%14%45%21%4
90
16th to endDay
19%9%37%28%31
81
March1st to 15thDay
18%13%38%23%5%
90
16th to endDay
28%6%25%22%13%2
162
April1st to 15thDay
24%8%27%27%10%1
270
16th to endDay
33%10%22%20%12%
318
May1st to 15thDay
24%11%31%22%8%1
468
16th to endDay
18%10%27%24%14%4
481
June1st to 15thDay
21%7%26%27%12%4
420
16th to endDay
11%7%31%25%17%6%
420
July1st to 15thDay
11%422%29%20%11%
400
16th to endDay
8%422%33%20%9%
445
August1st to 15thDay
10%323%30%26%5%
418
16th to endDay
18%417%30%23%5%
322
September1st to 15thDay
14%5%19%32%18%8%
255
16th to endDay
17%424%32%17%2
202
October1st to 15thDay
11%11%28%30%12%6%
90
16th to endDay
28%10%29%26%5%1
96
November1st to 15thDay
7%6%31%38%12%3
90
16th to endDay
40%6%35%12%41
90
December1st to 15thDay
25%8%35%26%3
90
16th to endDay
32%17%38%9%2
96
January1st to 15thNight
18%9%33%29%8%1
900
16th to endNight
20%8%35%29%5%
960
February1st to 15thNight
14%10%34%31%8%
880
16th to endNight
16%10%34%29%7%
693
March1st to 15thNight
16%9%31%32%8%1
651
16th to endNight
22%6%29%28%11%1
576
April1st to 15thNight
25%6%33%27%7%
539
16th to endNight
27%6%30%27%8%
540
May1st to 15thNight
25%5%33%29%5%1
540
16th to endNight
15%6%26%35%13%2
542
June1st to 15thNight
16%6%25%40%10%
495
16th to endNight
11%227%43%13%1
495
July1st to 15thNight
7%325%35%25%2
465
16th to endNight
6%20%45%23%2
522
August1st to 15thNight
8%114%44%28%2
494
16th to endNight
15%122%33%24%2
525
September1st to 15thNight
11%321%38%19%6%
495
16th to endNight
15%6%25%31%19%1
580
October1st to 15thNight
19%6%27%28%16%1
660
16th to endNight
24%7%25%31%10%
704
November1st to 15thNight
20%7%33%28%8%
757
16th to endNight
22%12%32%23%8%
900
December1st to 15thNight
23%9%35%23%7%
900
16th to endNight
28%7%28%27%7%1
960
Page generated at 2017-05-25 12:27:36. Version ac04

Copyright 2017 A. Danko


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