Hutville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hutville clear sky chart from 2005-11-06 to 2024-01-11.

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
39%
23869
16%
74353
11%
23815
45%
23815
20%
51451

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
15%
760
13%
2459
5%
757
24%
757
10%
1936
January11th to 20thNight
15%
724
10%
2352
4%
724
23%
724
10%
1874
January21st to endNight
21%
792
12%
2574
7%
792
27%
792
11%
2021
February1st to 10thNight
20%
720
10%
2340
5%
720
26%
720
11%
1802
February11th to 20thNight
19%
700
12%
2141
6%
700
24%
700
12%
1608
February21st to endNight
14%
592
13%
1776
4%
592
24%
592
13%
1371
March1st to 10thNight
26%
720
15%
2068
8%
720
33%
720
18%
1483
March11th to 20thNight
30%
720
19%
1980
10%
720
37%
720
22%
1375
March21st to endNight
28%
792
17%
2178
8%
792
35%
792
19%
1567
April1st to 10thNight
30%
712
15%
1972
8%
712
36%
712
24%
1354
April11th to 20thNight
34%
533
20%
1620
11%
533
43%
533
23%
1078
April21st to endNight
30%
540
17%
1620
6%
540
40%
540
22%
1109
May1st to 10thNight
35%
540
12%
1620
7%
540
40%
540
19%
1159
May11th to 20thNight
41%
531
16%
1593
11%
531
46%
531
22%
1094
May21st to endNight
61%
583
15%
1745
13%
582
64%
582
30%
1096
June1st to 10thNight
58%
540
15%
1620
13%
540
62%
540
30%
1009
June11th to 20thNight
58%
540
17%
1620
13%
540
63%
540
30%
996
June21st to endNight
58%
540
18%
1471
14%
540
63%
540
32%
945
July1st to 10thNight
66%
525
15%
1511
15%
525
67%
525
32%
948
July11th to 20thNight
70%
522
18%
1566
16%
522
72%
522
34%
920
July21st to endNight
65%
591
18%
1672
14%
558
67%
558
30%
1038
August1st to 10thNight
70%
537
18%
1600
16%
534
70%
534
33%
960
August11th to 20thNight
64%
534
20%
1598
17%
534
66%
534
31%
1001
August21st to endNight
71%
594
24%
1788
20%
594
73%
594
38%
1002
September1st to 10thNight
62%
706
22%
1966
16%
706
64%
706
34%
1202
September11th to 20thNight
68%
720
30%
1980
24%
720
70%
720
42%
1135
September21st to endNight
51%
720
25%
1980
19%
720
57%
720
32%
1250
October1st to 10thNight
53%
720
24%
2047
20%
720
58%
720
33%
1243
October11th to 20thNight
36%
720
21%
2160
14%
720
45%
720
25%
1416
October21st to endNight
31%
792
21%
2414
15%
792
40%
792
20%
1691
November1st to 10thNight
41%
740
22%
2406
17%
740
49%
740
27%
1449
November11th to 20thNight
30%
760
19%
2470
12%
760
40%
760
18%
1690
November21st to endNight
28%
760
16%
2470
11%
760
35%
760
15%
1780
December1st to 10thNight
21%
760
11%
2470
6%
760
26%
760
11%
1934
December11th to 20thNight
21%
759
12%
2997
6%
758
29%
758
11%
2195
December21st to endNight
16%
830
6%
4509
5%
817
23%
817
5%
3720

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%9%47%6%45%5%5%7%32%
75054
Night
14%9%47%6%35%5%5%7%35%
74627
TransparencyDay
50%7%11%20%11%2
74777
Night
48%6%11%20%13%2
74423
SeeingDay
19%11%26%22%15%6%
13912
Night
18%9%28%29%14%2
23880

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
17%14%8%9%9%5%5%5%46%18%
1706
11th to 20thDay
18%17%9%11%8%5%3335%18%
1620
21st to endDay
15%17%9%11%9%45%45%5%18%
1782
February1st to 10thDay
20%15%6%10%8%4433422%
1620
11th to 20thDay
16%12%6%13%9%3445%6%22%
1703
21st to endDay
17%16%5%9%7%23347%27%
1480
March1st to 10thDay
18%10%6%7%6%445%5%6%29%
1890
11th to 20thDay
18%13%5%8%6%34446%29%
1980
21st to endDay
22%9%47%6%44446%28%
2178
April1st to 10thDay
14%12%47%6%3445%7%33%
2003
11th to 20thDay
17%11%46%6%44347%35%
2288
21st to endDay
19%8%37%6%4446%6%32%
2340
May1st to 10thDay
19%8%36%7%45%5%5%7%32%
2340
11th to 20thDay
19%8%37%6%35%5%5%8%31%
2301
21st to endDay
9%6%36%6%46%8%7%9%37%
2531
June1st to 10thDay
11%5%36%7%45%6%7%8%37%
2340
11th to 20thDay
12%5%37%6%36%5%6%9%37%
2340
21st to endDay
11%5%25%6%46%7%8%10%36%
2472
July1st to 10thDay
11%5%36%6%46%5%7%9%38%
2390
11th to 20thDay
10%6%25%5%35%6%6%10%41%
2340
21st to endDay
10%5%35%6%5%6%6%8%9%38%
2547
August1st to 10thDay
8%5%25%6%46%7%7%10%40%
2327
11th to 20thDay
10%6%25%7%47%7%9%10%35%
2303
21st to endDay
8%5%25%5%36%6%7%9%42%
2561
September1st to 10thDay
13%5%35%43445%7%45%
1980
11th to 20thDay
10%5%25%5%36%5%5%9%45%
1980
21st to endDay
17%6%25%5%34446%44%
1980
October1st to 10thDay
14%6%36%5%345%5%8%40%
1913
11th to 20thDay
14%8%36%5%35%46%7%39%
1800
21st to endDay
21%10%37%6%3445%6%32%
1940
November1st to 10thDay
10%8%35%5%35%5%5%7%45%
1672
11th to 20thDay
17%10%5%6%7%3345%5%34%
1710
21st to endDay
18%13%5%7%7%34346%30%
1710
December1st to 10thDay
18%17%8%10%6%35%446%19%
1710
11th to 20thDay
17%14%6%12%7%35%45%5%22%
2153
21st to endDay
23%22%7%10%6%34435%11%
3124
January1st to 10thNight
16%15%6%10%8%46%34423%
2459
11th to 20thNight
18%15%6%11%7%45%445%21%
2352
21st to endNight
15%15%7%10%7%46%446%22%
2574
February1st to 10thNight
20%14%49%7%45%35%5%25%
2340
11th to 20thNight
17%11%5%9%8%36%46%6%25%
2140
21st to endNight
18%13%5%10%7%34445%26%
1776
March1st to 10thNight
15%9%5%7%6%35%5%6%6%33%
2068
11th to 20thNight
15%9%5%6%5%3445%8%36%
1980
21st to endNight
19%11%47%5%3445%6%33%
2178
April1st to 10thNight
14%8%46%5%35%5%5%8%37%
1972
11th to 20thNight
14%7%46%7%35%5%6%7%37%
1620
21st to endNight
14%8%37%6%345%5%7%37%
1620
May1st to 10thNight
16%8%36%6%46%6%5%7%32%
1620
11th to 20thNight
17%8%36%5%2446%9%36%
1592
21st to endNight
7%5%35%5%36%6%8%10%41%
1744
June1st to 10thNight
8%5%35%6%35%5%6%8%46%
1620
11th to 20thNight
8%5%25%5%35%5%8%11%43%
1620
21st to endNight
10%425%5%35%6%7%9%45%
1471
July1st to 10thNight
8%425%5%35%6%6%8%47%
1556
11th to 20thNight
7%325%5%35%6%7%11%47%
1620
21st to endNight
8%6%25%5%45%6%7%7%44%
1771
August1st to 10thNight
5%435%6%45%7%7%10%45%
1611
11th to 20thNight
8%6%26%6%35%46%8%46%
1598
21st to endNight
7%423445%6%7%8%52%
1788
September1st to 10thNight
11%5%25%434448%50%
1966
11th to 20thNight
8%5%24333448%56%
1980
21st to endNight
14%5%25%5%3445%5%47%
1980
October1st to 10thNight
11%5%25%5%3346%8%48%
2047
11th to 20thNight
15%8%27%435%45%6%40%
2160
21st to endNight
21%8%36%5%345%46%35%
2414
November1st to 10thNight
13%7%35%5%3445%6%46%
2406
11th to 20thNight
16%9%5%8%5%34447%35%
2470
21st to endNight
18%12%47%6%35%5%5%6%29%
2470
December1st to 10thNight
19%14%6%10%6%45%45%5%23%
2470
11th to 20thNight
16%12%7%9%7%345%5%6%26%
3042
21st to endNight
23%19%8%9%6%34445%15%
4532

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
67%5%8%14%6%
1707
11th to 20thDay
71%411%11%3
1620
21st to endDay
69%5%8%12%5%1
1782
February1st to 10thDay
67%5%9%13%6%1
1620
11th to 20thDay
63%5%8%15%7%1
1713
21st to endDay
60%49%18%6%2
1480
March1st to 10thDay
55%5%11%22%7%1
1890
11th to 20thDay
56%6%10%18%9%1
1980
21st to endDay
57%6%9%20%8%1
2178
April1st to 10thDay
51%5%13%17%12%1
2003
11th to 20thDay
50%6%11%17%14%3
2288
21st to endDay
52%6%10%20%11%2
2340
May1st to 10thDay
50%7%13%18%9%2
2340
11th to 20thDay
52%7%13%16%11%1
2305
21st to endDay
40%10%14%23%12%1
2531
June1st to 10thDay
42%8%11%24%14%1
2340
11th to 20thDay
41%9%14%21%13%1
2340
21st to endDay
40%10%14%20%14%2
2472
July1st to 10thDay
41%9%13%22%14%2
2325
11th to 20thDay
37%7%15%25%15%1
2271
21st to endDay
38%8%15%25%12%2
2405
August1st to 10thDay
36%10%15%26%13%1
2314
11th to 20thDay
38%11%14%25%11%1
2303
21st to endDay
34%8%15%22%15%5%
2561
September1st to 10thDay
37%7%11%22%19%3
1980
11th to 20thDay
36%6%12%26%18%3
1980
21st to endDay
42%410%23%20%1
1980
October1st to 10thDay
41%7%10%23%18%1
1913
11th to 20thDay
44%6%11%22%16%2
1800
21st to endDay
53%5%12%19%9%1
1940
November1st to 10thDay
38%5%11%26%17%3
1672
11th to 20thDay
52%5%9%21%11%3
1710
21st to endDay
57%410%19%9%1
1710
December1st to 10thDay
67%5%9%15%3
1710
11th to 20thDay
65%49%17%5%
2150
21st to endDay
76%6%8%7%3
3124
January1st to 10thNight
66%47%16%7%
2459
11th to 20thNight
65%5%12%13%5%
2352
21st to endNight
64%5%9%15%6%1
2574
February1st to 10thNight
63%411%15%6%1
2340
11th to 20thNight
59%410%16%9%1
2141
21st to endNight
61%49%15%8%2
1776
March1st to 10thNight
52%5%10%21%11%1
2068
11th to 20thNight
47%5%11%24%10%3
1980
21st to endNight
53%49%21%12%2
2178
April1st to 10thNight
45%6%11%22%14%2
1972
11th to 20thNight
44%6%12%17%19%3
1620
21st to endNight
45%7%11%20%15%2
1620
May1st to 10thNight
50%8%11%19%10%3
1620
11th to 20thNight
46%7%10%20%14%3
1593
21st to endNight
33%10%16%26%12%2
1745
June1st to 10thNight
35%9%13%23%18%2
1620
11th to 20thNight
34%8%14%25%17%2
1620
21st to endNight
33%10%13%25%17%2
1471
July1st to 10thNight
34%8%13%21%19%4
1511
11th to 20thNight
29%9%14%27%18%2
1566
21st to endNight
34%9%15%26%14%3
1672
August1st to 10thNight
32%8%18%25%16%1
1600
11th to 20thNight
35%8%15%24%17%1
1598
21st to endNight
27%7%17%25%19%4
1788
September1st to 10thNight
33%7%12%23%19%6%
1966
11th to 20thNight
28%5%12%28%25%3
1980
21st to endNight
37%5%10%22%24%1
1980
October1st to 10thNight
34%6%12%26%20%2
2047
11th to 20thNight
43%5%10%26%15%1
2160
21st to endNight
50%5%8%23%12%2
2414
November1st to 10thNight
38%5%12%23%18%3
2406
11th to 20thNight
50%48%21%14%2
2470
21st to endNight
55%412%20%7%1
2470
December1st to 10thNight
63%6%9%17%5%
2470
11th to 20thNight
58%5%12%19%6%
3044
21st to endNight
73%5%9%11%3
4532

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
26%21%34%13%6%1
270
11th to 20thDay
25%17%44%11%21
240
21st to endDay
26%23%33%14%3
264
February1st to 10thDay
31%25%31%12%
240
11th to 20thDay
31%29%30%9%1
240
21st to endDay
30%28%32%8%1
198
March1st to 10thDay
23%22%34%17%4
330
11th to 20thDay
27%14%35%19%5%
420
21st to endDay
29%15%32%19%41
462
April1st to 10thDay
22%16%32%18%10%2
420
11th to 20thDay
25%16%28%16%11%5%
412
21st to endDay
25%14%32%20%7%2
420
May1st to 10thDay
27%11%30%18%10%4
423
11th to 20thDay
21%9%25%26%14%5%
447
21st to endDay
13%6%22%28%20%10%
485
June1st to 10thDay
11%5%26%34%19%6%
450
11th to 20thDay
14%8%21%28%22%6%
450
21st to endDay
13%7%25%29%19%7%
582
July1st to 10thDay
13%315%24%24%20%
495
11th to 20thDay
11%420%26%25%13%
444
21st to endDay
11%219%27%27%13%
488
August1st to 10thDay
11%413%25%30%17%
446
11th to 20thDay
13%418%28%24%13%
439
21st to endDay
8%316%30%28%15%
495
September1st to 10thDay
13%417%25%28%13%
450
11th to 20thDay
12%314%24%33%15%
450
21st to endDay
20%8%20%24%19%8%
450
October1st to 10thDay
12%8%26%28%20%7%
450
11th to 20thDay
16%15%32%24%11%2
450
21st to endDay
27%13%32%20%7%1
455
November1st to 10thDay
16%15%36%19%12%2
270
11th to 20thDay
23%19%30%17%9%2
270
21st to endDay
26%19%36%16%3
270
December1st to 10thDay
25%21%33%16%42
270
11th to 20thDay
22%21%41%12%3
270
21st to endDay
32%19%31%15%3
297
January1st to 10thNight
24%17%37%19%4
760
11th to 20thNight
27%15%34%19%3
724
21st to endNight
23%14%36%24%3
792
February1st to 10thNight
27%12%36%23%2
720
11th to 20thNight
24%16%37%21%2
703
21st to endNight
27%14%39%19%2
592
March1st to 10thNight
21%13%36%25%5%
720
11th to 20thNight
20%14%33%26%8%
720
21st to endNight
22%12%31%27%7%1
792
April1st to 10thNight
18%12%36%27%6%1
712
11th to 20thNight
16%13%33%26%10%2
533
21st to endNight
19%6%39%27%8%1
540
May1st to 10thNight
20%8%29%29%13%1
540
11th to 20thNight
20%426%34%13%2
531
21st to endNight
9%321%37%28%3
584
June1st to 10thNight
8%323%42%23%1
540
11th to 20thNight
10%419%42%23%2
540
21st to endNight
11%222%40%22%3
540
July1st to 10thNight
10%213%40%27%8%
525
11th to 20thNight
8%114%39%33%5%
522
21st to endNight
10%213%38%34%3
591
August1st to 10thNight
8%19%44%32%5%
537
11th to 20thNight
10%213%38%32%5%
534
21st to endNight
8%212%37%34%8%
594
September1st to 10thNight
14%315%31%31%6%
706
11th to 20thNight
10%313%37%31%6%
720
21st to endNight
15%5%23%31%24%3
720
October1st to 10thNight
13%6%22%35%20%4
720
11th to 20thNight
19%9%31%28%12%1
720
21st to endNight
24%10%31%27%8%
792
November1st to 10thNight
16%9%29%30%15%1
740
11th to 20thNight
21%14%30%26%8%1
760
21st to endNight
23%11%33%26%7%1
760
December1st to 10thNight
28%12%33%23%4
760
11th to 20thNight
24%12%36%23%5%
760
21st to endNight
29%13%32%22%3
836
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