Fort Smith
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Smith clear sky chart from 2005-11-06 to 2024-11-05.

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
34%
24761
3%
99102
1%
24559
35%
24559
4%
82756

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
23%
1017
2%
5362
1%
1006
25%
1006
2%
5037
January11th to 20thNight
27%
1017
8%
5186
2%
1010
28%
1010
2%
4086
January21st to endNight
25%
1085
2%
5370
1%
1069
26%
1069
1%
4633
February1st to 10thNight
33%
950
4%
2850
3%
950
34%
950
4%
2633
February11th to 20thNight
32%
746
3%
2561
2%
746
34%
746
4%
2288
February21st to endNight
35%
628
5%
2041
3%
628
37%
628
5%
1817
March1st to 10thNight
45%
754
6%
3814
6%
744
46%
744
4%
3067
March11th to 20thNight
33%
753
5%
3415
3%
740
34%
740
4%
2751
March21st to endNight
43%
814
5%
3320
3%
805
45%
805
7%
2249
April1st to 10thNight
36%
570
6%
1710
4%
570
38%
570
7%
1473
April11th to 20thNight
44%
563
3%
1686
2%
563
45%
563
8%
1437
April21st to endNight
41%
439
1%
1389
1%
439
41%
439
7%
1186
May1st to 10thNight
39%
377
0%
2145
0%
373
40%
373
4%
1550
May11th to 20thNight
38%
371
0%
1865
0%
364
38%
364
5%
1379
May21st to endNight
45%
406
0%
1713
0%
399
46%
399
6%
1218
June1st to 10thNight
37%
380
0%
950
0%
380
37%
380
5%
873
June11th to 20thNight
50%
380
0%
950
0%
380
50%
380
9%
833
June21st to endNight
58%
380
0%
950
0%
380
58%
380
8%
834
July1st to 10thNight
55%
360
0%
1496
0%
360
55%
360
6%
1081
July11th to 20thNight
59%
361
0%
1358
0%
359
59%
359
9%
936
July21st to endNight
61%
407
0%
1829
0%
383
63%
383
5%
1357
August1st to 10thNight
58%
371
0%
1939
0%
366
59%
366
6%
1327
August11th to 20thNight
46%
370
0%
1944
0%
365
46%
365
4%
1425
August21st to endNight
43%
606
2%
3069
1%
592
45%
592
4%
2392
September1st to 10thNight
40%
570
4%
1710
3%
570
41%
570
6%
1504
September11th to 20thNight
42%
677
7%
2007
5%
677
43%
677
9%
1692
September21st to endNight
33%
760
5%
2095
3%
760
35%
760
8%
1813
October1st to 10thNight
30%
753
7%
3690
2%
740
32%
740
3%
3033
October11th to 20thNight
28%
756
3%
3984
0%
740
31%
740
2%
3296
October21st to endNight
21%
1038
2%
4758
0%
1022
22%
1022
2%
4263
November1st to 10thNight
22%
950
3%
2805
1%
950
23%
950
3%
2605
November11th to 20thNight
19%
950
1%
3025
0%
950
20%
950
2%
2838
November21st to endNight
20%
986
1%
3116
0%
986
21%
986
2%
2934
December1st to 10thNight
23%
1040
1%
3230
0%
1040
25%
1040
2%
3046
December11th to 20thNight
26%
1040
2%
3985
1%
1039
28%
1039
2%
3735
December21st to endNight
30%
1136
3%
5785
3%
1114
31%
1114
3%
4135

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
9%9%49%6%6%6%5%7%7%32%
106180
Night
8%12%5%12%7%7%7%5%6%6%26%
101391
TransparencyDay
25%48%8%14%5%
105883
Night
30%48%8%11%4
101334
SeeingDay
15%9%28%29%15%4
16967
Night
14%8%30%31%15%3
24933

By Month

Percentage Cloud Cover NW (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
5%10%5%17%14%13%12%7%6%37%
1579
11th to 20thDay
411%312%9%8%13%9%10%9%12%
1638
21st to endDay
10%21%6%13%7%7%5%5%9%6%13%
2254
February1st to 10thDay
49%7%15%10%9%9%6%8%7%16%
1339
11th to 20thDay
411%413%8%6%8%6%8%9%22%
1513
21st to endDay
310%5%14%11%10%6%7%9%7%19%
1413
March1st to 10thDay
5%9%5%11%9%8%8%6%9%8%23%
2979
11th to 20thDay
410%6%16%8%7%6%6%7%7%24%
3478
21st to endDay
36%410%6%6%5%46%7%43%
3895
April1st to 10thDay
8%13%49%7%5%5%45%6%35%
2470
11th to 20thDay
5%9%39%6%5%5%47%6%40%
2445
21st to endDay
9%9%39%6%5%5%47%8%36%
2788
May1st to 10thDay
7%7%38%5%5%5%5%7%9%39%
4740
11th to 20thDay
10%11%39%5%5%5%46%7%34%
4995
21st to endDay
15%5%25%45%5%5%6%9%41%
5857
June1st to 10thDay
13%10%39%5%5%5%46%7%33%
3230
11th to 20thDay
13%7%28%6%6%5%46%8%35%
3230
21st to endDay
7%6%27%5%6%6%5%7%8%40%
3230
July1st to 10thDay
7%5%38%6%7%7%5%9%10%33%
5380
11th to 20thDay
10%5%26%5%5%5%46%7%46%
5380
21st to endDay
12%6%27%5%6%7%5%8%10%34%
5551
August1st to 10thDay
7%426%5%5%5%35%7%52%
4720
11th to 20thDay
13%7%38%5%5%446%6%39%
4626
21st to endDay
15%7%38%6%6%6%5%7%9%29%
4534
September1st to 10thDay
16%9%37%5%5%5%47%8%31%
2470
11th to 20thDay
15%10%49%5%5%445%7%31%
2171
21st to endDay
16%12%49%6%5%5%46%7%29%
2085
October1st to 10thDay
11%19%5%7%5%5%336%7%30%
3149
11th to 20thDay
14%16%5%10%5%4436%7%27%
2811
21st to endDay
8%19%10%15%6%5%5%45%6%18%
2754
November1st to 10thDay
15%19%7%14%5%6%5%34418%
1370
11th to 20thDay
10%19%7%20%10%9%433312%
1155
21st to endDay
9%20%7%17%9%8%5%34413%
1064
December1st to 10thDay
5%18%6%17%11%8%6%7%5%5%11%
950
11th to 20thDay
7%15%7%15%11%6%9%5%7%7%12%
1199
21st to endDay
5%11%413%8%7%7%47%8%25%
1738
January1st to 10thNight
413%7%20%13%10%11%6%5%37%
5366
11th to 20thNight
5%10%412%7%7%14%9%10%6%15%
5260
21st to endNight
8%16%5%14%8%7%7%6%8%5%14%
5402
February1st to 10thNight
48%414%10%10%10%8%7%7%19%
2850
11th to 20thNight
410%5%13%7%7%6%6%7%8%25%
2559
21st to endNight
310%5%14%9%8%8%48%6%25%
2041
March1st to 10thNight
38%6%15%7%7%6%5%8%6%28%
3887
11th to 20thNight
6%10%414%7%6%7%48%7%27%
3501
21st to endNight
27%37%45%45%6%8%48%
3756
April1st to 10thNight
8%14%49%445%5%5%7%36%
1710
11th to 20thNight
49%37%6%4446%10%43%
1686
21st to endNight
6%8%38%6%6%5%5%8%9%36%
1389
May1st to 10thNight
10%8%37%5%45%5%6%8%39%
2220
11th to 20thNight
8%9%39%6%5%6%46%7%35%
1898
21st to endNight
15%6%26%5%4337%8%42%
1718
June1st to 10thNight
15%7%38%6%45%5%6%9%31%
950
11th to 20thNight
11%6%49%45%6%5%7%7%39%
950
21st to endNight
5%427%5%6%6%6%10%7%42%
950
July1st to 10thNight
8%6%27%5%6%6%7%7%10%36%
1580
11th to 20thNight
8%4245%5%5%5%7%9%47%
1580
21st to endNight
10%7%25%5%5%6%5%10%11%33%
1986
August1st to 10thNight
9%6%26%34435%6%52%
2210
11th to 20thNight
11%5%27%5%6%5%46%8%41%
2200
21st to endNight
16%7%38%6%5%5%46%7%32%
3133
September1st to 10thNight
14%9%37%5%5%5%47%9%33%
1710
11th to 20thNight
17%9%27%5%4436%7%35%
2007
21st to endNight
13%11%37%45%5%46%8%33%
2095
October1st to 10thNight
11%17%49%5%5%5%46%7%28%
3820
11th to 20thNight
13%16%6%9%5%5%5%45%7%25%
4086
21st to endNight
12%21%8%15%7%6%5%345%14%
4804
November1st to 10thNight
12%18%7%17%8%6%4345%16%
2805
11th to 20thNight
10%17%7%17%11%8%5%44412%
3025
21st to endNight
9%18%7%17%11%9%6%5%4410%
3116
December1st to 10thNight
8%17%8%17%9%8%8%6%6%5%11%
3230
11th to 20thNight
6%14%6%17%10%10%10%6%6%5%10%
3993
21st to endNight
5%11%412%8%8%7%5%6%6%28%
5918

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
52%40%431
1579
11th to 20thDay
36%41%9%10%4
1653
21st to endDay
43%41%8%5%3
2254
February1st to 10thDay
23%66%35%3
1339
11th to 20thDay
21%66%5%7%1
1521
21st to endDay
21%65%27%4
1413
March1st to 10thDay
33%43%9%14%1
2979
11th to 20thDay
34%42%6%14%4
3479
21st to endDay
19%41%5%18%17%
3895
April1st to 10thDay
15%65%49%7%
2470
11th to 20thDay
13%66%49%7%
2445
21st to endDay
14%66%413%3
2788
May1st to 10thDay
22%43%7%15%12%1
4740
11th to 20thDay
28%42%6%14%10%
4999
21st to endDay
22%42%8%18%9%
5858
June1st to 10thDay
20%66%47%3
3230
11th to 20thDay
17%66%39%5%
3230
21st to endDay
14%66%5%10%5%
3230
July1st to 10thDay
27%39%15%15%4
5296
11th to 20thDay
20%37%6%29%7%1
5287
21st to endDay
28%39%11%20%1
5375
August1st to 10thDay
18%38%10%24%9%1
4702
11th to 20thDay
25%39%7%16%13%
4671
21st to endDay
32%40%15%12%1
4533
September1st to 10thDay
21%61%9%8%1
2470
11th to 20thDay
20%60%8%10%1
2171
21st to endDay
21%61%7%8%3
2085
October1st to 10thDay
35%38%11%14%2
3149
11th to 20thDay
37%38%8%15%2
2811
21st to endDay
41%39%11%9%
2754
November1st to 10thDay
30%59%6%41
1370
11th to 20thDay
30%61%5%41
1155
21st to endDay
29%61%5%41
1064
December1st to 10thDay
29%62%6%21
950
11th to 20thDay
37%50%5%6%2
1200
21st to endDay
30%39%9%18%4
1738
January1st to 10thNight
53%39%441
5366
11th to 20thNight
35%40%10%11%5%
5307
21st to endNight
42%42%7%8%2
5402
February1st to 10thNight
23%66%46%2
2850
11th to 20thNight
20%65%6%8%1
2561
21st to endNight
19%65%46%5%1
2041
March1st to 10thNight
33%42%11%12%1
3887
11th to 20thNight
31%43%7%13%5%
3501
21st to endNight
14%41%5%23%16%
3756
April1st to 10thNight
14%65%311%6%
1710
11th to 20thNight
13%65%410%8%
1686
21st to endNight
12%66%414%4
1389
May1st to 10thNight
25%42%8%15%10%
2220
11th to 20thNight
25%44%7%15%8%1
1898
21st to endNight
25%42%5%17%11%1
1718
June1st to 10thNight
20%66%47%2
950
11th to 20thNight
14%65%5%10%7%
950
21st to endNight
14%67%5%7%7%
950
July1st to 10thNight
26%39%13%21%1
1555
11th to 20thNight
17%38%9%27%9%
1550
21st to endNight
28%38%13%20%1
1923
August1st to 10thNight
19%38%8%24%12%
2203
11th to 20thNight
22%39%8%17%14%1
2221
21st to endNight
34%39%15%11%1
3133
September1st to 10thNight
20%62%7%8%2
1710
11th to 20thNight
16%60%9%13%2
2007
21st to endNight
17%62%10%8%3
2095
October1st to 10thNight
39%38%9%15%
3820
11th to 20thNight
40%39%10%10%1
4086
21st to endNight
48%39%6%6%1
4804
November1st to 10thNight
31%58%5%6%
2805
11th to 20thNight
30%61%441
3025
21st to endNight
30%62%441
3116
December1st to 10thNight
30%61%5%22
3230
11th to 20thNight
40%51%433
3991
21st to endNight
27%40%16%12%5%
5918

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
8%12%35%29%14%1
180
11th to 20thDay
14%9%29%29%14%3
180
21st to endDay
18%13%34%21%10%4
198
February1st to 10thDay
11%7%37%26%14%6%
180
11th to 20thDay
6%8%39%28%15%3
195
21st to endDay
410%30%37%16%4
225
March1st to 10thDay
8%9%37%26%13%5%
360
11th to 20thDay
11%13%37%31%7%2
460
21st to endDay
10%13%37%25%12%4
506
April1st to 10thDay
15%15%35%21%12%3
460
11th to 20thDay
10%10%35%29%11%5%
457
21st to endDay
14%10%30%30%14%2
650
May1st to 10thDay
18%10%28%29%14%1
653
11th to 20thDay
13%11%26%29%17%4
706
21st to endDay
13%9%28%33%14%3
940
June1st to 10thDay
22%9%28%29%10%3
870
11th to 20thDay
17%9%29%28%14%3
870
21st to endDay
8%7%24%36%20%4
870
July1st to 10thDay
15%8%22%35%14%6%
856
11th to 20thDay
12%6%19%37%22%5%
852
21st to endDay
12%5%21%30%25%6%
904
August1st to 10thDay
12%6%20%29%25%8%
676
11th to 20thDay
21%9%24%31%14%2
659
21st to endDay
19%9%21%32%16%3
539
September1st to 10thDay
23%11%30%20%11%4
490
11th to 20thDay
18%10%27%28%14%2
490
21st to endDay
20%13%31%28%7%1
485
October1st to 10thDay
28%9%29%21%9%5%
300
11th to 20thDay
23%13%35%20%7%2
300
21st to endDay
19%13%36%22%8%2
330
November1st to 10thDay
20%11%38%17%13%2
208
11th to 20thDay
19%10%40%19%8%3
180
21st to endDay
18%9%37%22%13%1
180
December1st to 10thDay
12%430%36%14%3
180
11th to 20thDay
14%8%33%27%14%5%
180
21st to endDay
6%7%29%32%14%12%
198
January1st to 10thNight
12%8%31%32%14%3
1040
11th to 20thNight
14%8%32%32%12%1
1040
21st to endNight
16%11%31%28%10%3
1097
February1st to 10thNight
7%9%35%31%14%5%
950
11th to 20thNight
8%8%35%35%13%2
750
21st to endNight
6%8%34%34%17%1
628
March1st to 10thNight
6%8%28%35%19%4
760
11th to 20thNight
12%9%33%33%11%1
760
21st to endNight
6%7%33%34%17%2
827
April1st to 10thNight
15%10%31%29%13%2
570
11th to 20thNight
7%7%34%34%17%1
563
21st to endNight
10%7%32%35%14%2
439
May1st to 10thNight
10%9%32%35%13%1
380
11th to 20thNight
12%7%34%31%15%1
374
21st to endNight
13%6%31%35%14%2
411
June1st to 10thNight
18%9%28%29%13%3
380
11th to 20thNight
13%423%39%20%1
380
21st to endNight
6%325%38%26%2
380
July1st to 10thNight
10%8%18%37%22%4
370
11th to 20thNight
11%218%40%25%3
368
21st to endNight
8%217%37%31%5%
416
August1st to 10thNight
13%416%39%22%5%
378
11th to 20thNight
16%5%22%37%17%2
376
21st to endNight
18%426%34%16%3
614
September1st to 10thNight
18%7%24%30%18%3
570
11th to 20thNight
22%6%23%33%13%3
677
21st to endNight
19%7%31%29%12%1
760
October1st to 10thNight
22%11%28%26%11%3
760
11th to 20thNight
22%7%31%27%11%2
760
21st to endNight
22%12%26%26%12%2
1045
November1st to 10thNight
17%8%30%27%15%2
950
11th to 20thNight
19%10%31%27%11%3
950
21st to endNight
18%11%32%25%13%2
986
December1st to 10thNight
15%7%31%34%11%2
1040
11th to 20thNight
13%11%35%27%12%3
1040
21st to endNight
12%8%29%26%20%5%
1144
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