Theodore Roosevelt National Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Theodore Roosevelt National Park clear sky chart from 2005-11-06 to 2024-01-14.

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
40%
24992
18%
74515
11%
24946
47%
24946
27%
46950

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
29%
947
17%
2647
7%
946
38%
946
25%
1775
January11th to 20thNight
30%
920
15%
2575
7%
920
36%
920
21%
1776
January21st to endNight
26%
990
14%
2772
6%
990
33%
990
17%
2049
February1st to 10thNight
32%
829
12%
2449
6%
829
38%
829
19%
1751
February11th to 20thNight
30%
700
15%
2195
8%
700
37%
700
20%
1485
February21st to endNight
38%
592
18%
1776
9%
592
46%
592
24%
1181
March1st to 10thNight
34%
720
14%
2160
9%
720
39%
720
22%
1467
March11th to 20thNight
38%
712
19%
2118
11%
712
46%
712
27%
1357
March21st to endNight
37%
594
13%
1980
10%
594
43%
594
17%
1395
April1st to 10thNight
36%
540
18%
1800
13%
540
45%
540
23%
1138
April11th to 20thNight
31%
533
16%
1771
10%
533
40%
533
20%
1174
April21st to endNight
42%
540
18%
1620
14%
540
48%
540
28%
1043
May1st to 10thNight
51%
540
17%
1455
9%
540
55%
540
32%
925
May11th to 20thNight
49%
531
16%
1418
10%
531
51%
531
32%
914
May21st to endNight
46%
584
12%
1552
6%
582
48%
582
27%
1055
June1st to 10thNight
47%
540
13%
1440
6%
540
50%
540
34%
902
June11th to 20thNight
43%
540
9%
1440
5%
540
45%
540
31%
927
June21st to endNight
56%
540
13%
1440
7%
540
59%
540
45%
821
July1st to 10thNight
57%
525
13%
1400
7%
525
59%
525
49%
777
July11th to 20thNight
57%
522
18%
1392
9%
522
61%
522
46%
781
July21st to endNight
62%
591
25%
1488
14%
558
66%
558
57%
742
August1st to 10thNight
60%
537
26%
1424
17%
534
64%
534
47%
786
August11th to 20thNight
64%
534
26%
1520
19%
534
70%
534
47%
801
August21st to endNight
58%
594
28%
1980
26%
594
67%
594
44%
970
September1st to 10thNight
62%
540
27%
1800
26%
540
71%
540
44%
878
September11th to 20thNight
54%
540
27%
1862
25%
540
63%
540
35%
988
September21st to endNight
46%
540
24%
1980
20%
540
55%
540
30%
1069
October1st to 10thNight
40%
657
21%
2097
17%
657
45%
657
27%
1292
October11th to 20thNight
42%
774
25%
2214
14%
774
48%
774
30%
1362
October21st to endNight
34%
990
21%
2574
7%
990
41%
990
30%
1679
November1st to 10thNight
37%
925
22%
2405
10%
925
44%
925
29%
1601
November11th to 20thNight
33%
950
22%
2588
9%
950
41%
950
28%
1694
November21st to endNight
34%
950
19%
2660
8%
950
43%
950
28%
1713
December1st to 10thNight
29%
950
15%
2660
7%
950
37%
950
22%
1876
December11th to 20thNight
30%
949
18%
3174
8%
948
40%
948
20%
2026
December21st to endNight
26%
1032
12%
4689
7%
1026
34%
1026
13%
2780

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%7%36%5%345%6%8%45%
74808
Night
8%7%36%5%35%5%5%7%45%
74978
TransparencyDay
37%7%15%26%13%2
74511
Night
38%7%14%25%14%2
74797
SeeingDay
12%8%30%31%16%3
14891
Night
11%8%34%35%11%1
25013

By Month

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 10thDay
5%9%5%6%7%47%6%7%8%38%
1518
11th to 20thDay
49%5%10%7%36%6%6%9%36%
1464
21st to endDay
410%5%10%8%5%7%6%6%9%31%
1584
February1st to 10thDay
7%11%6%9%7%45%5%6%7%33%
1526
11th to 20thDay
6%12%6%9%8%45%6%5%7%31%
1651
21st to endDay
411%6%11%7%45%5%6%8%33%
1480
March1st to 10thDay
7%11%410%8%45%45%7%35%
1800
11th to 20thDay
8%8%36%6%35%46%8%43%
1839
21st to endDay
12%11%47%6%35%5%6%7%34%
2376
April1st to 10thDay
10%8%47%7%445%6%8%37%
2160
11th to 20thDay
12%11%5%8%7%46%5%6%6%31%
2136
21st to endDay
14%7%36%6%345%6%8%38%
2340
May1st to 10thDay
14%9%25%5%35%5%5%8%40%
2502
11th to 20thDay
14%6%25%6%3445%8%43%
2478
21st to endDay
19%6%35%5%3446%8%36%
2724
June1st to 10thDay
14%5%344345%7%8%44%
2520
11th to 20thDay
11%425%5%35%6%6%8%43%
2520
21st to endDay
6%313435%46%10%55%
2520
July1st to 10thDay
6%3135%345%5%9%56%
2520
11th to 20thDay
5%21332445%7%63%
2520
21st to endDay
431442446%7%60%
2742
August1st to 10thDay
8%31332445%8%57%
2507
11th to 20thDay
7%41343345%8%56%
2378
21st to endDay
7%31432435%8%59%
2376
September1st to 10thDay
9%5%2432335%7%58%
2160
11th to 20thDay
10%42332345%9%55%
2097
21st to endDay
13%5%24323346%56%
1980
October1st to 10thDay
14%7%345%2345%6%47%
1859
11th to 20thDay
10%8%45%5%3445%8%45%
1728
21st to endDay
11%8%45%5%3445%8%44%
1782
November1st to 10thDay
10%10%5%6%4345%5%6%41%
1673
11th to 20thDay
5%9%47%5%35%5%6%10%41%
1588
21st to endDay
6%8%48%6%47%5%7%7%39%
1520
December1st to 10thDay
6%12%5%9%7%45%5%7%8%33%
1520
11th to 20thDay
5%9%5%8%445%5%5%8%42%
1926
21st to endDay
5%8%48%6%45%6%5%7%43%
2794
January1st to 10thNight
5%8%47%7%45%7%7%8%38%
2647
11th to 20thNight
5%9%5%8%8%45%6%6%7%37%
2575
21st to endNight
411%6%11%8%5%6%6%6%8%29%
2772
February1st to 10thNight
6%10%5%8%8%5%7%6%6%7%32%
2449
11th to 20thNight
5%10%5%8%7%46%5%7%8%35%
2194
21st to endNight
5%10%49%7%45%45%9%39%
1776
March1st to 10thNight
7%9%5%7%7%45%5%6%8%38%
2160
11th to 20thNight
9%8%46%5%35%5%6%7%44%
2118
21st to endNight
11%10%49%6%46%6%6%8%31%
1980
April1st to 10thNight
9%9%35%6%25%6%7%7%41%
1800
11th to 20thNight
12%9%47%6%35%6%6%8%36%
1771
21st to endNight
13%6%35%435%45%7%44%
1620
May1st to 10thNight
10%6%25%445%46%8%46%
1455
11th to 20thNight
13%6%244345%5%9%45%
1417
21st to endNight
17%5%34435%5%6%7%41%
1552
June1st to 10thNight
11%423425%46%9%48%
1440
11th to 20thNight
11%425%5%35%5%5%9%47%
1440
21st to endNight
5%3144245%5%7%59%
1440
July1st to 10thNight
5%3233235%5%10%59%
1440
11th to 20thNight
43144245%5%7%61%
1440
21st to endNight
321231346%7%68%
1576
August1st to 10thNight
6%413423448%60%
1432
11th to 20thNight
6%21332335%7%63%
1520
21st to endNight
5%41332346%8%61%
1980
September1st to 10thNight
7%22232345%7%63%
1800
11th to 20thNight
10%42442345%8%56%
1862
21st to endNight
12%5%24434446%53%
1980
October1st to 10thNight
14%8%35%42335%6%46%
2097
11th to 20thNight
10%8%345%25%447%49%
2214
21st to endNight
10%7%35%5%3445%8%45%
2574
November1st to 10thNight
9%8%36%5%35%5%6%7%43%
2405
11th to 20thNight
5%9%48%7%4445%8%42%
2588
21st to endNight
5%6%46%6%35%5%6%8%44%
2660
December1st to 10thNight
5%9%5%10%8%47%6%6%7%34%
2660
11th to 20thNight
6%8%48%7%445%6%7%42%
3271
21st to endNight
6%9%48%7%45%5%45%43%
4873

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
42%8%19%22%7%1
1519
11th to 20thDay
45%7%18%19%8%2
1464
21st to endDay
50%8%16%17%8%1
1584
February1st to 10thDay
50%6%13%21%10%
1526
11th to 20thDay
51%8%14%18%7%2
1660
21st to endDay
49%5%14%19%12%1
1480
March1st to 10thDay
49%8%16%20%7%1
1800
11th to 20thDay
38%7%17%28%11%
1839
21st to endDay
48%6%17%22%6%1
2376
April1st to 10thDay
42%8%17%20%12%1
2160
11th to 20thDay
51%7%13%19%9%
2139
21st to endDay
44%7%15%25%9%1
2340
May1st to 10thDay
42%7%13%26%11%1
2502
11th to 20thDay
39%9%13%27%12%
2482
21st to endDay
47%8%16%22%7%
2724
June1st to 10thDay
37%8%17%27%10%
2520
11th to 20thDay
36%8%16%28%10%3
2520
21st to endDay
24%8%21%29%15%2
2520
July1st to 10thDay
24%7%14%32%18%5%
2451
11th to 20thDay
20%5%13%29%25%8%
2445
21st to endDay
22%7%12%28%26%5%
2590
August1st to 10thDay
25%8%13%28%20%6%
2491
11th to 20thDay
26%7%12%32%19%4
2378
21st to endDay
24%5%11%28%29%3
2376
September1st to 10thDay
28%5%11%31%19%6%
2160
11th to 20thDay
28%6%14%31%18%3
2097
21st to endDay
32%412%31%19%2
1980
October1st to 10thDay
39%6%13%24%16%2
1859
11th to 20thDay
39%5%13%26%15%2
1728
21st to endDay
38%7%17%24%12%2
1782
November1st to 10thDay
44%5%12%24%14%2
1673
11th to 20thDay
38%6%16%26%12%2
1588
21st to endDay
43%7%19%22%8%1
1520
December1st to 10thDay
48%6%14%23%9%
1520
11th to 20thDay
40%6%22%28%4
1924
21st to endDay
40%6%11%29%13%1
2794
January1st to 10thNight
41%7%18%22%11%1
2647
11th to 20thNight
45%7%17%22%8%1
2575
21st to endNight
52%7%14%18%8%1
2772
February1st to 10thNight
49%7%16%17%10%
2449
11th to 20thNight
45%7%15%22%9%1
2195
21st to endNight
43%6%15%22%12%2
1776
March1st to 10thNight
43%8%16%24%9%
2160
11th to 20thNight
38%7%14%28%13%1
2118
21st to endNight
50%8%15%18%8%1
1980
April1st to 10thNight
40%8%14%23%14%2
1800
11th to 20thNight
45%7%13%21%13%1
1771
21st to endNight
40%6%15%28%11%
1620
May1st to 10thNight
34%8%13%28%15%2
1455
11th to 20thNight
35%8%15%29%13%
1418
21st to endNight
41%8%17%25%10%
1552
June1st to 10thNight
32%7%15%30%13%1
1440
11th to 20thNight
34%9%18%26%12%1
1440
21st to endNight
24%7%18%33%17%2
1440
July1st to 10thNight
21%7%18%33%16%5%
1400
11th to 20thNight
22%7%10%30%22%8%
1392
21st to endNight
15%6%14%34%25%6%
1488
August1st to 10thNight
22%6%12%31%20%8%
1424
11th to 20thNight
22%6%14%29%24%5%
1520
21st to endNight
21%5%10%31%26%6%
1980
September1st to 10thNight
21%5%10%34%23%7%
1800
11th to 20thNight
27%6%14%28%20%4
1862
21st to endNight
32%5%12%28%22%1
1980
October1st to 10thNight
39%5%13%25%15%3
2097
11th to 20thNight
36%5%11%30%16%2
2214
21st to endNight
38%6%14%26%14%2
2574
November1st to 10thNight
39%7%12%23%16%3
2405
11th to 20thNight
41%5%15%27%10%2
2588
21st to endNight
38%7%20%23%11%1
2660
December1st to 10thNight
47%7%16%20%9%1
2660
11th to 20thNight
41%7%19%25%8%
3272
21st to endNight
43%5%10%26%14%1
4873

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
10%9%36%26%14%4
270
11th to 20thDay
8%12%41%26%11%2
249
21st to endDay
9%16%41%27%7%
264
February1st to 10thDay
11%10%44%31%4
240
11th to 20thDay
13%10%38%30%7%1
240
21st to endDay
8%13%41%28%9%1
198
March1st to 10thDay
18%11%37%23%8%3
240
11th to 20thDay
14%9%33%27%12%4
271
21st to endDay
14%11%32%26%14%3
462
April1st to 10thDay
14%15%35%27%9%1
420
11th to 20thDay
20%16%34%23%6%2
417
21st to endDay
19%9%26%31%15%2
600
May1st to 10thDay
17%7%26%30%16%5%
603
11th to 20thDay
17%6%23%30%18%6%
625
21st to endDay
17%7%26%27%18%5%
679
June1st to 10thDay
13%8%25%29%20%5%
630
11th to 20thDay
11%9%34%30%13%3
630
21st to endDay
7%6%30%34%20%3
630
July1st to 10thDay
7%5%23%40%22%4
621
11th to 20thDay
8%6%27%39%18%3
618
21st to endDay
6%226%40%22%4
684
August1st to 10thDay
7%420%39%24%5%
626
11th to 20thDay
8%422%36%24%6%
588
21st to endDay
9%424%31%25%7%
495
September1st to 10thDay
10%6%34%29%17%4
450
11th to 20thDay
11%6%23%37%18%4
387
21st to endDay
16%7%33%25%15%4
270
October1st to 10thDay
22%7%21%27%17%5%
270
11th to 20thDay
11%11%35%25%13%4
270
21st to endDay
15%15%36%24%8%1
297
November1st to 10thDay
15%13%38%19%14%2
270
11th to 20thDay
10%13%34%30%11%2
270
21st to endDay
9%11%37%33%10%
270
December1st to 10thDay
10%11%39%28%11%1
270
11th to 20thDay
12%10%43%27%7%1
270
21st to endDay
5%13%39%30%12%1
297
January1st to 10thNight
8%10%42%29%10%1
950
11th to 20thNight
10%13%37%29%10%1
920
21st to endNight
10%12%40%31%7%
990
February1st to 10thNight
10%10%38%31%10%1
829
11th to 20thNight
9%10%41%30%9%1
704
21st to endNight
8%7%36%35%12%3
592
March1st to 10thNight
10%11%38%33%7%1
720
11th to 20thNight
11%6%39%33%9%2
712
21st to endNight
14%7%31%36%12%
594
April1st to 10thNight
12%10%35%35%8%
540
11th to 20thNight
16%11%36%29%8%1
533
21st to endNight
17%6%29%36%12%
540
May1st to 10thNight
12%5%26%41%16%1
540
11th to 20thNight
15%427%39%15%
531
21st to endNight
19%6%25%36%13%1
584
June1st to 10thNight
12%7%30%36%14%1
540
11th to 20thNight
12%8%31%37%12%1
540
21st to endNight
6%429%45%15%1
540
July1st to 10thNight
4333%46%14%
525
11th to 20thNight
6%5%30%50%11%
522
21st to endNight
3230%51%14%
591
August1st to 10thNight
7%325%49%15%1
537
11th to 20thNight
6%322%47%21%1
534
21st to endNight
8%327%42%19%1
594
September1st to 10thNight
8%324%47%17%1
540
11th to 20thNight
11%5%26%43%15%1
540
21st to endNight
15%5%32%36%12%1
540
October1st to 10thNight
18%8%29%34%12%1
657
11th to 20thNight
14%10%28%36%11%1
774
21st to endNight
14%10%37%28%10%1
990
November1st to 10thNight
13%10%35%33%9%1
925
11th to 20thNight
9%10%40%30%10%
950
21st to endNight
8%12%39%33%9%
950
December1st to 10thNight
9%9%41%32%9%
950
11th to 20thNight
11%12%36%33%7%1
950
21st to endNight
16%10%36%28%10%
1045
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