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 2005-11-06 to 2024-03-18.

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%
25094
16%
80748
9%
25000
42%
25000
21%
54809

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
25%
942
12%
4381
6%
926
33%
926
11%
3194
January11th to 20thNight
22%
946
10%
4361
6%
930
27%
930
9%
3342
January21st to endNight
21%
1032
7%
4634
3%
1023
27%
1023
8%
3587
February1st to 10thNight
26%
950
15%
2470
5%
950
32%
950
21%
1807
February11th to 20thNight
26%
929
19%
2404
6%
925
34%
925
24%
1657
February21st to endNight
28%
633
16%
1889
6%
633
36%
633
19%
1314
March1st to 10thNight
29%
746
18%
2266
10%
746
36%
746
23%
1488
March11th to 20thNight
32%
564
21%
2068
14%
564
44%
564
20%
1314
March21st to endNight
35%
594
18%
2080
16%
594
41%
594
18%
1402
April1st to 10thNight
25%
540
15%
1800
9%
540
36%
540
19%
1213
April11th to 20thNight
32%
533
18%
1775
14%
533
41%
533
19%
1227
April21st to endNight
33%
540
17%
1714
10%
540
42%
540
21%
1143
May1st to 10thNight
29%
540
15%
1440
8%
540
34%
540
22%
1037
May11th to 20thNight
38%
531
19%
1417
10%
531
44%
531
29%
939
May21st to endNight
47%
584
14%
1551
7%
582
51%
582
29%
1018
June1st to 10thNight
49%
540
16%
1440
7%
540
53%
540
33%
917
June11th to 20thNight
46%
540
15%
1440
7%
540
49%
540
34%
914
June21st to endNight
54%
540
18%
1440
8%
540
58%
540
38%
868
July1st to 10thNight
62%
525
18%
1400
10%
525
64%
525
47%
784
July11th to 20thNight
58%
522
20%
1392
10%
522
61%
522
41%
822
July21st to endNight
68%
591
22%
1487
13%
558
72%
558
51%
798
August1st to 10thNight
66%
537
23%
1506
19%
534
69%
534
39%
882
August11th to 20thNight
58%
534
22%
1600
20%
534
64%
534
34%
948
August21st to endNight
56%
594
21%
1979
22%
594
61%
594
34%
1093
September1st to 10thNight
55%
540
23%
1800
23%
540
62%
540
33%
1005
September11th to 20thNight
52%
540
27%
1800
23%
540
59%
540
35%
997
September21st to endNight
43%
684
21%
2027
14%
684
51%
684
32%
1209
October1st to 10thNight
44%
720
22%
2160
15%
720
49%
720
32%
1288
October11th to 20thNight
30%
720
20%
2160
10%
720
39%
720
23%
1424
October21st to endNight
32%
792
16%
2488
10%
792
40%
792
19%
1715
November1st to 10thNight
31%
740
22%
2406
14%
740
43%
740
23%
1532
November11th to 20thNight
23%
946
14%
2656
6%
946
31%
946
19%
1914
November21st to endNight
25%
950
16%
2660
7%
950
33%
950
21%
1858
December1st to 10thNight
24%
950
11%
2660
4%
950
30%
950
18%
1957
December11th to 20thNight
18%
948
12%
3212
3%
948
25%
948
11%
2430
December21st to endNight
18%
1037
7%
4785
4%
1026
25%
1026
7%
3772

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%9%47%6%35%5%5%7%36%
78570
Night
14%10%47%5%3445%6%37%
81274
TransparencyDay
49%312%24%10%1
78270
Night
49%311%24%12%1
81094
SeeingDay
17%9%29%26%14%4
15022
Night
18%8%31%31%11%1
25129

By Month

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 10thDay
12%17%8%13%7%34345%23%
2527
11th to 20thDay
8%11%5%14%9%6%9%10%6%417%
2530
21st to endDay
14%18%8%12%6%34446%22%
2979
February1st to 10thDay
9%10%6%9%6%46%5%5%6%33%
1710
11th to 20thDay
11%9%47%7%445%6%8%35%
1664
21st to endDay
13%10%5%10%6%45%5%47%31%
1564
March1st to 10thDay
15%10%5%6%5%45%446%36%
1928
11th to 20thDay
14%9%47%6%45%45%7%36%
2057
21st to endDay
19%10%37%6%4446%7%32%
2276
April1st to 10thDay
16%11%47%6%3445%6%33%
2160
11th to 20thDay
22%10%46%6%3445%5%31%
2134
21st to endDay
22%10%37%6%35%5%45%30%
2244
May1st to 10thDay
16%8%36%6%35%5%6%8%34%
2520
11th to 20thDay
18%7%36%6%45%45%6%37%
2479
21st to endDay
16%5%25%6%445%6%7%39%
2725
June1st to 10thDay
14%5%25%4345%6%8%44%
2520
11th to 20thDay
14%5%35%6%46%5%5%9%38%
2520
21st to endDay
12%5%25%5%45%6%7%10%40%
2520
July1st to 10thDay
7%4245%36%6%8%9%46%
2520
11th to 20thDay
10%4245%36%5%7%10%45%
2520
21st to endDay
7%4245%45%6%6%9%49%
2743
August1st to 10thDay
10%5%25%6%45%6%8%9%40%
2421
11th to 20thDay
13%5%36%5%445%6%8%42%
2301
21st to endDay
12%5%2443445%8%48%
2376
September1st to 10thDay
14%6%35%5%2345%7%46%
2160
11th to 20thDay
13%5%35%6%3445%7%46%
2160
21st to endDay
16%6%35%4345%5%7%41%
1912
October1st to 10thDay
17%6%35%5%345%5%6%41%
1800
11th to 20thDay
18%11%36%5%35%5%46%33%
1800
21st to endDay
22%12%45%433345%36%
1867
November1st to 10thDay
14%8%47%6%34447%39%
1672
11th to 20thDay
17%12%6%9%6%45%446%28%
1520
21st to endDay
15%12%46%7%3436%5%36%
1520
December1st to 10thDay
11%13%5%12%9%5%6%5%46%25%
1520
11th to 20thDay
12%14%7%10%8%45%44427%
1918
21st to endDay
22%18%7%13%7%3423319%
2783
January1st to 10thNight
10%16%9%13%6%3434429%
4428
11th to 20thNight
10%11%6%13%9%5%7%9%6%420%
4440
21st to endNight
14%19%8%11%7%3444422%
4685
February1st to 10thNight
7%11%6%10%8%46%45%5%33%
2470
11th to 20thNight
8%9%48%6%36%5%5%7%38%
2403
21st to endNight
14%10%46%8%4445%6%34%
1889
March1st to 10thNight
12%8%46%6%445%5%7%40%
2266
11th to 20thNight
12%9%47%5%4445%6%40%
2068
21st to endNight
20%8%36%5%34445%37%
2080
April1st to 10thNight
19%10%345%345%5%6%35%
1800
11th to 20thNight
24%8%36%43445%5%35%
1775
21st to endNight
21%9%35%5%3345%7%36%
1714
May1st to 10thNight
21%8%36%5%35%45%5%34%
1440
11th to 20thNight
19%5%26%43345%7%42%
1416
21st to endNight
14%5%36%5%35%5%5%8%42%
1551
June1st to 10thNight
12%5%244445%5%9%45%
1440
11th to 20thNight
12%424435%5%6%8%45%
1440
21st to endNight
10%3345%35%6%7%8%48%
1440
July1st to 10thNight
8%3233235%5%9%56%
1440
11th to 20thNight
8%414435%5%5%8%53%
1440
21st to endNight
5%2143345%5%10%58%
1575
August1st to 10thNight
9%415%435%5%6%8%50%
1515
11th to 20thNight
13%5%25%42445%7%49%
1600
21st to endNight
12%424324445%55%
1979
September1st to 10thNight
11%425%5%3445%6%52%
1800
11th to 20thNight
12%5%245%33447%52%
1800
21st to endNight
15%425%42445%7%48%
2027
October1st to 10thNight
16%5%24433347%48%
2160
11th to 20thNight
17%8%36%5%3445%7%39%
2160
21st to endNight
19%11%36%5%34445%36%
2488
November1st to 10thNight
14%10%5%5%42345%7%40%
2406
11th to 20thNight
15%10%5%9%6%34446%33%
2656
21st to endNight
15%11%47%5%3445%6%36%
2660
December1st to 10thNight
12%13%5%9%8%34446%30%
2660
11th to 20thNight
13%15%5%11%8%45%445%26%
3279
21st to endNight
25%15%6%10%6%3334421%
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
65%211%17%4
2528
11th to 20thDay
69%27%16%7%
2530
21st to endDay
65%213%16%4
2979
February1st to 10thDay
52%313%20%11%1
1710
11th to 20thDay
48%412%26%9%1
1673
21st to endDay
54%310%23%9%2
1564
March1st to 10thDay
51%214%21%11%1
1928
11th to 20thDay
50%312%22%12%1
2057
21st to endDay
53%311%24%8%1
2276
April1st to 10thDay
52%310%21%12%1
2160
11th to 20thDay
56%29%19%12%2
2134
21st to endDay
57%311%19%9%1
2244
May1st to 10thDay
50%412%24%9%1
2520
11th to 20thDay
49%312%22%12%1
2483
21st to endDay
44%5%11%25%13%2
2725
June1st to 10thDay
39%313%31%12%2
2520
11th to 20thDay
43%413%26%14%1
2520
21st to endDay
39%5%16%29%10%2
2520
July1st to 10thDay
33%416%32%14%1
2451
11th to 20thDay
34%5%14%28%17%3
2445
21st to endDay
31%417%31%16%2
2591
August1st to 10thDay
38%5%14%31%10%2
2406
11th to 20thDay
41%314%29%12%
2301
21st to endDay
35%412%31%17%1
2376
September1st to 10thDay
38%413%30%15%
2160
11th to 20thDay
39%316%33%8%1
2160
21st to endDay
43%412%31%10%
1912
October1st to 10thDay
43%212%30%11%
1800
11th to 20thDay
52%311%23%10%1
1800
21st to endDay
53%213%24%9%
1867
November1st to 10thDay
46%412%22%14%2
1672
11th to 20thDay
58%312%18%8%1
1520
21st to endDay
50%316%22%7%1
1520
December1st to 10thDay
62%313%17%5%
1520
11th to 20thDay
61%215%15%5%2
1915
21st to endDay
74%26%14%4
2783
January1st to 10thNight
61%210%21%6%1
4428
11th to 20thNight
66%210%15%7%
4440
21st to endNight
67%28%17%5%1
4685
February1st to 10thNight
53%310%22%10%2
2470
11th to 20thNight
46%412%28%9%1
2404
21st to endNight
52%212%21%11%2
1889
March1st to 10thNight
45%413%27%9%2
2266
11th to 20thNight
47%210%25%14%2
2068
21st to endNight
51%39%23%12%1
2080
April1st to 10thNight
50%48%19%18%2
1800
11th to 20thNight
53%27%20%15%2
1775
21st to endNight
49%29%23%15%2
1714
May1st to 10thNight
51%411%20%13%1
1440
11th to 20thNight
43%310%27%16%2
1417
21st to endNight
42%413%22%17%1
1552
June1st to 10thNight
37%5%11%30%17%1
1440
11th to 20thNight
36%5%13%25%18%2
1440
21st to endNight
33%415%33%13%3
1440
July1st to 10thNight
26%412%36%20%2
1400
11th to 20thNight
29%414%30%20%3
1392
21st to endNight
22%319%32%19%5%
1487
August1st to 10thNight
31%414%31%16%3
1506
11th to 20thNight
35%415%27%18%2
1600
21st to endNight
33%314%29%17%4
1979
September1st to 10thNight
34%411%32%19%1
1800
11th to 20thNight
33%213%35%15%
1800
21st to endNight
37%313%33%13%1
2027
October1st to 10thNight
38%210%35%14%2
2160
11th to 20thNight
47%213%24%13%1
2160
21st to endNight
52%311%22%12%1
2488
November1st to 10thNight
44%311%26%14%1
2406
11th to 20thNight
53%314%17%12%1
2656
21st to endNight
50%315%24%7%1
2660
December1st to 10thNight
56%314%21%5%
2660
11th to 20thNight
61%312%18%6%1
3281
21st to endNight
69%28%16%5%
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
16%13%32%26%11%3
270
11th to 20thDay
19%11%39%22%7%1
270
21st to endDay
21%9%34%26%8%2
297
February1st to 10thDay
16%14%43%19%7%2
270
11th to 20thDay
16%19%37%20%8%
270
21st to endDay
17%15%41%26%1
225
March1st to 10thDay
19%14%38%19%9%1
270
11th to 20thDay
20%10%37%20%10%2
261
21st to endDay
24%12%31%21%10%3
362
April1st to 10thDay
25%11%34%21%6%2
420
11th to 20thDay
28%13%25%24%9%1
412
21st to endDay
27%13%23%25%9%2
491
May1st to 10thDay
21%11%32%26%9%2
603
11th to 20thDay
22%11%27%24%13%4
625
21st to endDay
18%8%24%29%15%5%
679
June1st to 10thDay
13%7%24%33%18%5%
630
11th to 20thDay
15%6%34%28%13%3
630
21st to endDay
13%7%27%29%15%8%
630
July1st to 10thDay
9%420%29%26%12%
621
11th to 20thDay
11%5%24%31%21%8%
618
21st to endDay
6%424%36%21%9%
684
August1st to 10thDay
10%422%31%25%8%
626
11th to 20thDay
13%5%18%28%28%8%
615
21st to endDay
15%6%21%28%24%6%
495
September1st to 10thDay
17%6%24%29%19%5%
450
11th to 20thDay
12%6%27%31%20%4
450
21st to endDay
19%9%29%27%14%3
364
October1st to 10thDay
18%11%28%23%16%5%
270
11th to 20thDay
21%16%34%22%7%1
270
21st to endDay
28%14%34%18%42
297
November1st to 10thDay
18%11%36%24%9%3
270
11th to 20thDay
21%17%34%23%5%
270
21st to endDay
22%13%41%17%7%
270
December1st to 10thDay
15%14%36%27%7%1
270
11th to 20thDay
19%14%38%21%8%
270
21st to endDay
28%13%40%16%3
297
January1st to 10thNight
15%10%36%29%9%1
950
11th to 20thNight
18%8%36%29%7%1
950
21st to endNight
20%9%32%30%8%1
1045
February1st to 10thNight
12%13%37%30%7%1
950
11th to 20thNight
13%12%39%28%7%1
929
21st to endNight
19%11%34%29%6%
633
March1st to 10thNight
16%11%37%27%8%1
746
11th to 20thNight
17%10%33%32%7%1
564
21st to endNight
23%8%28%28%11%2
594
April1st to 10thNight
25%8%36%24%6%1
540
11th to 20thNight
28%7%28%30%8%
533
21st to endNight
24%7%31%27%10%1
540
May1st to 10thNight
25%6%33%30%6%1
540
11th to 20thNight
20%6%30%32%9%2
531
21st to endNight
16%6%24%38%16%1
584
June1st to 10thNight
13%5%27%42%13%
540
11th to 20thNight
13%6%28%41%11%1
540
21st to endNight
11%424%44%15%2
540
July1st to 10thNight
8%321%40%26%3
525
11th to 20thNight
8%424%38%23%3
522
21st to endNight
6%120%47%23%3
591
August1st to 10thNight
9%115%47%26%1
537
11th to 20thNight
13%316%36%28%3
534
21st to endNight
14%222%36%24%3
594
September1st to 10thNight
12%422%41%17%4
540
11th to 20thNight
13%426%37%18%3
540
21st to endNight
16%8%29%32%14%1
684
October1st to 10thNight
18%7%26%32%16%1
720
11th to 20thNight
20%11%33%28%8%1
720
21st to endNight
24%8%29%30%9%
792
November1st to 10thNight
20%10%33%30%7%1
740
11th to 20thNight
21%12%36%24%7%
946
21st to endNight
21%13%36%23%7%
950
December1st to 10thNight
20%9%36%27%8%1
950
11th to 20thNight
22%9%35%24%7%1
950
21st to endNight
28%10%31%25%6%
1045
Page generated at 2024-03-15 13:01:42. Version ac07

Copyright © 2024 Attilla Danko.


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