Mountain Home
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mountain Home clear sky chart from 2005-11-06 to 2025-02-06.

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
43%
25510
22%
105917
16%
25160
52%
25160
23%
59911

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%
987
20%
5700
7%
956
38%
956
12%
3311
January11th to 20thNight
23%
995
18%
5273
9%
960
34%
960
15%
2864
January21st to endNight
23%
1089
23%
6067
8%
1056
35%
1056
14%
3578
February1st to 10thNight
26%
976
21%
2536
7%
976
33%
976
26%
1726
February11th to 20thNight
21%
831
20%
2306
6%
827
31%
827
25%
1487
February21st to endNight
19%
628
23%
1884
7%
628
32%
628
23%
1168
March1st to 10thNight
28%
567
24%
3382
14%
555
41%
555
13%
1963
March11th to 20thNight
30%
563
24%
3424
14%
550
38%
550
15%
1661
March21st to endNight
27%
620
12%
3649
10%
605
37%
605
13%
2058
April1st to 10thNight
29%
570
26%
1900
13%
570
47%
570
27%
1096
April11th to 20thNight
34%
563
25%
1875
16%
563
49%
563
27%
1089
April21st to endNight
30%
570
20%
1900
11%
570
44%
570
24%
1178
May1st to 10thNight
41%
565
20%
3051
14%
559
50%
559
17%
1724
May11th to 20thNight
45%
548
18%
2782
18%
541
52%
541
20%
1541
May21st to endNight
51%
608
15%
2826
13%
593
57%
593
20%
1622
June1st to 10thNight
67%
570
24%
1520
20%
570
70%
570
43%
888
June11th to 20thNight
73%
570
28%
1520
24%
570
76%
570
53%
800
June21st to endNight
68%
570
28%
1520
21%
570
72%
570
50%
816
July1st to 10thNight
72%
544
21%
2540
20%
535
74%
535
25%
1348
July11th to 20thNight
80%
536
23%
2404
26%
533
82%
533
34%
1138
July21st to endNight
75%
608
18%
2880
28%
569
77%
569
22%
1671
August1st to 10thNight
75%
551
32%
2486
27%
544
77%
544
35%
1011
August11th to 20thNight
70%
549
16%
2796
28%
544
73%
544
25%
1418
August21st to endNight
76%
607
22%
2997
29%
605
78%
605
31%
1314
September1st to 10thNight
72%
570
30%
1900
31%
570
76%
570
39%
1002
September11th to 20thNight
68%
570
29%
1900
28%
570
71%
570
31%
1097
September21st to endNight
64%
670
31%
2166
27%
670
69%
670
39%
1139
October1st to 10thNight
64%
760
30%
2190
23%
740
67%
740
44%
1160
October11th to 20thNight
46%
760
30%
2275
18%
740
57%
740
35%
1295
October21st to endNight
40%
836
24%
2786
18%
814
49%
814
25%
1764
November1st to 10thNight
43%
780
32%
2340
19%
780
56%
780
36%
1313
November11th to 20thNight
40%
800
28%
2566
16%
800
53%
800
34%
1391
November21st to endNight
36%
910
25%
2710
14%
910
47%
910
27%
1642
December1st to 10thNight
32%
991
31%
4320
10%
980
44%
980
22%
2246
December11th to 20thNight
31%
992
17%
4881
10%
978
39%
978
15%
2864
December21st to endNight
25%
1086
14%
6665
8%
1059
36%
1059
9%
4528

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
12%6%26%44435%7%46%
108397
Night
13%6%25%43435%6%49%
110020
TransparencyDay
36%5%10%25%19%4
112043
Night
35%410%25%20%5%
114514
SeeingDay
16%10%24%25%18%5%
15753
Night
16%9%26%31%16%2
25708

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
16%9%36%43323446%
4077
11th to 20thDay
9%7%26%43335%6%52%
4080
21st to endDay
21%6%35%23324447%
4488
February1st to 10thDay
17%9%36%5%34335%43%
1755
11th to 20thDay
16%7%27%33335%5%44%
1762
21st to endDay
17%11%35%5%45%35%5%38%
1586
March1st to 10thDay
18%10%36%34324444%
3436
11th to 20thDay
13%6%25%33335%6%51%
3480
21st to endDay
16%7%27%5%4435%6%40%
3836
April1st to 10thDay
11%6%36%5%4435%6%46%
2280
11th to 20thDay
15%6%36%44445%6%41%
2254
21st to endDay
18%10%37%444446%39%
2280
May1st to 10thDay
13%7%37%5%45%5%7%8%37%
3823
11th to 20thDay
13%6%27%5%5%446%8%40%
4082
21st to endDay
13%7%37%5%5%5%46%7%38%
4720
June1st to 10thDay
8%5%25%5%5%6%46%10%44%
2660
11th to 20thDay
6%4145%5%6%5%8%11%47%
2660
21st to endDay
4415%5%5%5%5%7%9%51%
2660
July1st to 10thDay
10%5%26%5%5%5%47%10%42%
4200
11th to 20thDay
5%31445%5%5%7%12%49%
4120
21st to endDay
7%6%27%5%6%7%6%8%10%35%
4465
August1st to 10thDay
431434435%9%60%
4104
11th to 20thDay
10%6%26%44447%9%44%
3802
21st to endDay
5%325%445%5%6%8%54%
4180
September1st to 10thDay
12%5%25%44446%6%48%
2280
11th to 20thDay
12%6%25%44446%7%45%
2280
21st to endDay
10%425%435%35%6%53%
1989
October1st to 10thDay
8%5%25%34335%6%57%
1900
11th to 20thDay
15%415%232236%56%
1900
21st to endDay
18%7%25%323246%49%
2090
November1st to 10thDay
13%6%24332335%56%
1958
11th to 20thDay
11%6%26%443345%52%
1830
21st to endDay
18%7%25%333345%48%
1688
December1st to 10thDay
12%7%25%443245%53%
2610
11th to 20thDay
15%8%37%433345%45%
3008
21st to endDay
18%15%38%444345%31%
4074
January1st to 10thNight
15%7%37%44435%6%41%
5888
11th to 20thNight
10%6%28%434345%51%
5900
21st to endNight
18%9%35%332235%46%
6490
February1st to 10thNight
16%9%36%44335%7%42%
2536
11th to 20thNight
16%7%37%433345%45%
2305
21st to endNight
16%8%24443245%47%
1884
March1st to 10thNight
22%8%25%323245%43%
3419
11th to 20thNight
13%7%25%333245%52%
3480
21st to endNight
13%7%36%5%45%45%6%41%
3793
April1st to 10thNight
11%6%25%434446%51%
1900
11th to 20thNight
13%5%25%43445%6%49%
1875
21st to endNight
17%6%25%44345%7%43%
1900
May1st to 10thNight
16%6%25%43435%7%45%
3069
11th to 20thNight
12%7%35%44446%9%43%
2823
21st to endNight
11%7%37%5%3446%8%42%
2844
June1st to 10thNight
8%325%43346%11%52%
1520
11th to 20thNight
431333436%11%58%
1520
21st to endNight
332343436%9%59%
1520
July1st to 10thNight
8%425%45%5%47%10%48%
2750
11th to 20thNight
432344446%8%60%
2850
21st to endNight
5%6%37%6%5%5%5%7%8%43%
3098
August1st to 10thNight
231333346%9%63%
2836
11th to 20thNight
6%426%445%46%8%52%
3029
21st to endNight
431423445%8%62%
3476
September1st to 10thNight
8%42423346%8%56%
1900
11th to 20thNight
10%5%25%44446%7%49%
1900
21st to endNight
7%5%25%333346%59%
2166
October1st to 10thNight
7%41432335%6%62%
2280
11th to 20thNight
12%424224245%58%
2280
21st to endNight
17%5%24333235%52%
2508
November1st to 10thNight
12%5%24323345%57%
2340
11th to 20thNight
11%6%24332346%56%
2566
21st to endNight
15%7%24333346%49%
2710
December1st to 10thNight
13%6%25%423247%52%
4580
11th to 20thNight
17%8%26%33323447%
5199
21st to endNight
23%11%37%444345%32%
6886

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
43%39%26%17%2
4078
11th to 20thDay
32%39%28%22%5%
4080
21st to endDay
42%27%18%23%8%
4488
February1st to 10thDay
46%410%24%14%3
1755
11th to 20thDay
42%48%24%17%4
1771
21st to endDay
47%48%20%14%8%
1586
March1st to 10thDay
45%37%18%17%10%
3436
11th to 20thDay
35%49%27%20%6%
3480
21st to endDay
44%411%24%16%1
3836
April1st to 10thDay
38%5%8%26%20%3
2280
11th to 20thDay
42%5%11%21%16%5%
2254
21st to endDay
47%5%9%22%15%2
2280
May1st to 10thDay
44%6%12%23%14%1
3858
11th to 20thDay
41%7%14%25%12%1
4086
21st to endDay
44%7%11%23%14%2
4733
June1st to 10thDay
35%8%16%24%17%1
2660
11th to 20thDay
29%8%15%29%17%3
2660
21st to endDay
27%7%16%27%20%4
2660
July1st to 10thDay
36%7%15%27%13%2
4136
11th to 20thDay
25%7%11%34%21%2
4051
21st to endDay
40%9%16%26%8%1
4325
August1st to 10thDay
21%6%17%31%21%3
4090
11th to 20thDay
37%6%13%30%14%1
3839
21st to endDay
26%6%13%36%16%3
4179
September1st to 10thDay
35%6%11%24%17%7%
2280
11th to 20thDay
36%7%8%22%24%3
2280
21st to endDay
31%6%7%26%27%3
1989
October1st to 10thDay
17%35%17%45%14%
3160
11th to 20thDay
20%2422%40%11%
3140
21st to endDay
30%47%32%23%4
3428
November1st to 10thDay
32%38%26%24%7%
1958
11th to 20thDay
34%46%24%23%9%
1830
21st to endDay
40%39%21%24%3
1688
December1st to 10thDay
35%38%31%21%2
2610
11th to 20thDay
42%47%26%21%1
3005
21st to endDay
54%49%21%9%3
4074
January1st to 10thNight
43%411%24%15%3
5888
11th to 20thNight
36%49%21%27%3
5900
21st to endNight
43%28%21%22%4
6490
February1st to 10thNight
43%49%25%15%3
2536
11th to 20thNight
41%49%24%19%4
2306
21st to endNight
39%49%22%18%7%
1884
March1st to 10thNight
45%39%17%16%9%
3419
11th to 20thNight
36%49%28%20%4
3480
21st to endNight
42%49%29%14%1
3793
April1st to 10thNight
34%5%10%23%22%6%
1900
11th to 20thNight
35%5%10%25%19%6%
1875
21st to endNight
40%5%10%26%15%3
1900
May1st to 10thNight
40%6%14%25%14%2
3099
11th to 20thNight
38%6%16%26%13%2
2824
21st to endNight
38%7%14%28%13%1
2852
June1st to 10thNight
27%6%13%33%20%2
1520
11th to 20thNight
20%5%14%36%21%4
1520
21st to endNight
21%6%16%30%20%7%
1520
July1st to 10thNight
30%7%18%25%17%3
2705
11th to 20thNight
21%6%12%35%24%3
2796
21st to endNight
36%7%17%28%12%
2999
August1st to 10thNight
17%6%16%37%22%2
2826
11th to 20thNight
29%5%17%30%16%1
3058
21st to endNight
21%5%14%34%22%3
3476
September1st to 10thNight
26%5%11%30%19%8%
1900
11th to 20thNight
33%7%10%21%24%5%
1900
21st to endNight
27%410%23%31%5%
2166
October1st to 10thNight
13%37%15%40%21%
3800
11th to 20thNight
19%25%17%38%19%
3779
21st to endNight
28%37%28%28%6%
4120
November1st to 10thNight
31%39%25%25%7%
2340
11th to 20thNight
30%48%24%26%8%
2566
21st to endNight
37%48%24%23%4
2710
December1st to 10thNight
34%39%35%17%2
4580
11th to 20thNight
42%37%23%21%4
5201
21st to endNight
53%5%9%22%8%2
6886

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
29%19%32%17%31
300
11th to 20thDay
27%20%35%15%2
300
21st to endDay
24%22%34%17%3
330
February1st to 10thDay
26%18%38%13%5%
285
11th to 20thDay
30%22%30%13%41
270
21st to endDay
36%24%29%8%2
225
March1st to 10thDay
30%18%33%16%3
270
11th to 20thDay
33%21%31%13%3
270
21st to endDay
28%24%37%8%3
307
April1st to 10thDay
22%18%31%20%8%1
460
11th to 20thDay
23%17%33%19%6%1
452
21st to endDay
23%15%34%20%5%2
460
May1st to 10thDay
21%17%30%22%9%
495
11th to 20thDay
16%12%31%23%16%3
675
21st to endDay
11%8%34%26%16%5%
734
June1st to 10thDay
10%5%22%28%27%8%
680
11th to 20thDay
7%219%38%29%6%
680
21st to endDay
5%424%34%27%7%
680
July1st to 10thDay
8%314%33%32%10%
671
11th to 20thDay
4313%35%32%13%
668
21st to endDay
7%113%31%32%15%
739
August1st to 10thDay
8%313%37%32%8%
676
11th to 20thDay
12%313%32%32%9%
528
21st to endDay
10%28%29%35%17%
539
September1st to 10thDay
11%311%32%32%10%
490
11th to 20thDay
13%311%31%30%13%
490
21st to endDay
11%8%22%30%24%6%
319
October1st to 10thDay
10%7%25%32%22%4
300
11th to 20thDay
16%14%34%25%9%2
300
21st to endDay
30%14%27%21%6%1
330
November1st to 10thDay
17%12%34%22%11%3
300
11th to 20thDay
22%13%33%21%10%1
300
21st to endDay
30%15%27%19%8%2
300
December1st to 10thDay
22%25%29%14%8%3
300
11th to 20thDay
26%22%26%19%7%
300
21st to endDay
28%22%32%15%4
330
January1st to 10thNight
23%16%32%25%4
1000
11th to 20thNight
23%16%34%24%31
1000
21st to endNight
20%15%37%25%3
1100
February1st to 10thNight
23%13%35%25%4
976
11th to 20thNight
22%16%37%23%1
831
21st to endNight
24%18%36%20%2
628
March1st to 10thNight
22%14%31%29%3
570
11th to 20thNight
23%13%31%28%5%
570
21st to endNight
22%13%34%27%5%
627
April1st to 10thNight
14%16%38%27%5%
570
11th to 20thNight
15%16%31%30%8%
563
21st to endNight
18%10%37%26%8%1
570
May1st to 10thNight
15%8%30%38%9%
570
11th to 20thNight
17%7%26%30%19%2
561
21st to endNight
11%7%22%35%21%4
617
June1st to 10thNight
10%314%38%33%2
570
11th to 20thNight
5%214%46%31%3
570
21st to endNight
5%118%41%32%3
570
July1st to 10thNight
6%210%36%37%8%
555
11th to 20thNight
419%38%40%7%
552
21st to endNight
5%18%38%40%8%
624
August1st to 10thNight
5%19%39%40%6%
567
11th to 20thNight
7%113%40%36%4
564
21st to endNight
9%17%34%41%7%
627
September1st to 10thNight
9%211%36%39%3
570
11th to 20thNight
12%19%36%35%7%
570
21st to endNight
9%5%16%36%31%3
670
October1st to 10thNight
9%319%37%29%3
760
11th to 20thNight
15%8%29%32%16%1
760
21st to endNight
22%9%27%31%11%
836
November1st to 10thNight
15%8%31%33%13%
780
11th to 20thNight
17%10%29%34%10%
800
21st to endNight
21%11%29%29%10%
910
December1st to 10thNight
22%11%30%30%6%
1000
11th to 20thNight
24%13%27%30%6%
1000
21st to endNight
25%16%28%27%3
1100
Page generated at 2025-02-03 02:05:56. Version ac07

Copyright © 2025 Attilla Danko.


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