Dallas (OR)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dallas (OR) clear sky chart from 2005-11-06 to 2024-03-08.

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
49%
22853
13%
80743
13%
22762
52%
22762
18%
56706

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
30%
753
4%
4398
5%
736
33%
736
4%
3820
January11th to 20thNight
34%
756
8%
4400
9%
740
36%
740
6%
3597
January21st to endNight
40%
834
8%
4514
13%
814
43%
814
7%
3774
February1st to 10thNight
37%
760
7%
2470
7%
760
39%
760
11%
2013
February11th to 20thNight
37%
740
9%
2404
7%
740
41%
740
13%
1865
February21st to endNight
35%
628
10%
1983
8%
628
38%
628
12%
1543
March1st to 10thNight
40%
750
10%
2120
8%
750
41%
750
14%
1674
March11th to 20thNight
42%
720
12%
1980
9%
720
45%
720
16%
1535
March21st to endNight
34%
792
7%
2156
4%
792
36%
792
13%
1741
April1st to 10thNight
39%
720
9%
1800
4%
720
41%
720
16%
1419
April11th to 20thNight
42%
694
12%
1762
6%
694
44%
694
22%
1296
April21st to endNight
49%
540
13%
1620
9%
540
52%
540
20%
1138
May1st to 10thNight
53%
446
15%
1526
13%
446
57%
446
25%
947
May11th to 20thNight
55%
354
14%
1416
17%
354
59%
354
19%
887
May21st to endNight
53%
389
11%
1552
12%
388
59%
388
20%
953
June1st to 10thNight
56%
360
11%
1440
16%
360
59%
360
21%
889
June11th to 20thNight
53%
360
11%
1440
16%
360
58%
360
26%
826
June21st to endNight
67%
360
18%
1440
25%
360
72%
360
39%
656
July1st to 10thNight
76%
350
20%
1400
29%
350
82%
350
50%
565
July11th to 20thNight
70%
348
27%
1392
35%
348
80%
348
52%
535
July21st to endNight
83%
426
32%
1519
40%
403
89%
403
72%
499
August1st to 10thNight
83%
537
28%
1602
25%
534
86%
534
62%
700
August11th to 20thNight
84%
534
33%
1602
27%
534
87%
534
61%
715
August21st to endNight
72%
703
34%
1891
22%
703
76%
703
55%
964
September1st to 10thNight
73%
720
31%
1800
18%
720
76%
720
60%
941
September11th to 20thNight
68%
720
27%
1826
18%
720
69%
720
41%
1122
September21st to endNight
67%
720
24%
2047
22%
720
70%
720
38%
1203
October1st to 10thNight
58%
720
17%
2160
18%
720
61%
720
31%
1314
October11th to 20thNight
59%
720
20%
2160
22%
720
61%
720
26%
1412
October21st to endNight
44%
792
18%
2377
14%
792
50%
792
21%
1640
November1st to 10thNight
42%
740
12%
2518
11%
740
44%
740
13%
1913
November11th to 20thNight
36%
760
9%
2660
8%
760
39%
760
11%
2101
November21st to endNight
42%
760
8%
2660
7%
760
44%
760
14%
1963
December1st to 10thNight
40%
760
11%
2660
10%
760
42%
760
13%
2025
December11th to 20thNight
31%
759
8%
3214
7%
759
32%
759
7%
2620
December21st to endNight
27%
828
4%
4834
6%
817
29%
817
4%
3901

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
16%8%47%6%45%5%5%6%34%
78533
Night
17%8%47%6%35%45%6%36%
81048
TransparencyDay
50%8%12%17%11%2
78239
Night
49%8%12%18%10%3
80864
SeeingDay
15%10%20%26%21%8%
13756
Night
17%5%19%36%21%2
22879

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
25%15%8%14%10%46%4347%
2539
11th to 20thDay
33%11%5%8%7%46%44415%
2540
21st to endDay
23%13%5%10%8%5%7%6%5%6%13%
3146
February1st to 10thDay
24%11%49%8%47%6%5%6%16%
1710
11th to 20thDay
22%13%5%9%8%5%6%5%5%5%18%
1665
21st to endDay
21%13%6%9%8%5%6%5%4419%
1470
March1st to 10thDay
20%12%49%7%48%5%6%7%18%
1997
11th to 20thDay
23%11%5%8%8%45%5%5%5%21%
1980
21st to endDay
22%11%6%10%9%47%5%5%6%16%
2199
April1st to 10thDay
21%11%5%9%8%5%6%5%5%6%19%
2160
11th to 20thDay
20%10%48%7%45%5%5%5%26%
2141
21st to endDay
17%9%47%6%46%6%6%7%27%
2340
May1st to 10thDay
13%8%37%6%45%5%6%6%36%
2434
11th to 20thDay
18%7%37%6%445%6%8%32%
2477
21st to endDay
17%6%35%6%46%6%6%8%32%
2723
June1st to 10thDay
18%7%47%7%35%5%5%5%34%
2520
11th to 20thDay
15%7%46%6%36%6%7%8%32%
2520
21st to endDay
7%4245%345%46%56%
2520
July1st to 10thDay
4324433447%61%
2520
11th to 20thDay
5%323223346%67%
2520
21st to endDay
4312212225%76%
2705
August1st to 10thDay
3312324347%67%
2328
11th to 20thDay
331332235%7%67%
2298
21st to endDay
442432345%8%61%
2464
September1st to 10thDay
6%21232335%7%66%
2160
11th to 20thDay
9%6%26%5%35%5%5%7%46%
2129
21st to endDay
14%5%25%5%35%447%47%
1912
October1st to 10thDay
14%6%36%6%45%46%5%41%
1800
11th to 20thDay
14%8%48%8%46%5%5%7%31%
1800
21st to endDay
17%11%49%7%45%446%29%
1978
November1st to 10thDay
21%10%6%10%8%5%6%6%6%417%
1556
11th to 20thDay
22%12%5%9%7%46%447%18%
1520
21st to endDay
21%10%49%7%5%6%5%5%5%23%
1520
December1st to 10thDay
20%12%7%10%8%3445%5%23%
1520
11th to 20thDay
21%10%5%12%9%5%7%6%7%7%13%
1928
21st to endDay
25%15%7%16%9%45%4347%
2794
January1st to 10thNight
25%18%6%10%8%5%5%44412%
4406
11th to 20thNight
30%14%5%8%7%3444417%
4416
21st to endNight
27%12%6%9%7%45%445%17%
4521
February1st to 10thNight
18%13%5%9%8%47%5%5%5%22%
2470
11th to 20thNight
21%10%48%6%45%5%5%5%27%
2402
21st to endNight
20%10%48%7%45%5%5%6%25%
1983
March1st to 10thNight
16%9%5%8%8%5%6%6%6%6%25%
2120
11th to 20thNight
18%8%38%7%46%6%6%7%26%
1980
21st to endNight
19%11%48%8%46%5%6%6%23%
2156
April1st to 10thNight
21%9%47%6%45%45%7%27%
1800
11th to 20thNight
16%8%36%6%46%45%7%35%
1762
21st to endNight
15%7%36%6%446%6%7%36%
1620
May1st to 10thNight
10%6%36%5%35%5%6%7%45%
1526
11th to 20thNight
13%6%26%5%5%6%5%6%8%39%
1416
21st to endNight
12%437%5%35%6%7%8%40%
1552
June1st to 10thNight
14%5%36%5%25%46%6%43%
1440
11th to 20thNight
11%6%35%42435%7%48%
1440
21st to endNight
5%5%24423236%65%
1440
July1st to 10thNight
3213223235%74%
1440
11th to 20thNight
4112212235%75%
1440
21st to endNight
21111113484%
1608
August1st to 10thNight
2212213346%75%
1611
11th to 20thNight
2213222335%76%
1602
21st to endNight
5%223323335%71%
1891
September1st to 10thNight
4212223335%72%
1800
11th to 20thNight
8%425%4345%46%55%
1826
21st to endNight
9%42443435%7%55%
2047
October1st to 10thNight
12%5%25%5%3445%5%50%
2160
11th to 20thNight
13%6%25%4446%5%7%43%
2160
21st to endNight
17%8%36%6%34445%40%
2377
November1st to 10thNight
21%7%38%7%45%5%6%6%27%
2518
11th to 20thNight
24%9%48%8%45%5%5%5%23%
2660
21st to endNight
19%7%39%7%45%5%5%6%30%
2660
December1st to 10thNight
22%9%49%7%45%5%5%6%26%
2660
11th to 20thNight
22%11%49%8%46%45%6%19%
3276
21st to endNight
22%12%5%12%9%45%5%45%18%
4862

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
79%9%5%5%21
2539
11th to 20thDay
71%8%8%9%22
2540
21st to endDay
72%9%7%7%5%
3146
February1st to 10thDay
68%9%9%10%4
1710
11th to 20thDay
67%9%9%10%41
1674
21st to endDay
68%7%9%10%6%1
1470
March1st to 10thDay
65%9%11%12%4
1997
11th to 20thDay
64%7%11%12%6%1
1980
21st to endDay
68%9%11%10%2
2199
April1st to 10thDay
66%8%11%11%4
2160
11th to 20thDay
59%8%10%13%7%3
2144
21st to endDay
55%10%12%13%8%1
2340
May1st to 10thDay
47%8%15%21%9%1
2434
11th to 20thDay
49%8%15%18%8%1
2480
21st to endDay
49%11%17%19%4
2724
June1st to 10thDay
50%8%16%20%5%1
2520
11th to 20thDay
48%10%20%17%6%
2520
21st to endDay
29%7%19%28%13%4
2520
July1st to 10thDay
23%7%15%26%22%7%
2451
11th to 20thDay
20%5%9%29%30%7%
2445
21st to endDay
11%49%33%35%8%
2555
August1st to 10thDay
17%6%16%34%21%6%
2312
11th to 20thDay
19%5%13%33%23%6%
2298
21st to endDay
22%6%12%32%23%4
2464
September1st to 10thDay
19%5%12%31%21%12%
2160
11th to 20thDay
35%8%14%20%16%6%
2129
21st to endDay
38%6%14%22%15%6%
1912
October1st to 10thDay
43%8%10%19%17%3
1800
11th to 20thDay
50%8%11%16%12%1
1800
21st to endDay
56%8%8%13%13%1
1978
November1st to 10thDay
66%8%10%12%4
1556
11th to 20thDay
65%9%9%9%6%1
1520
21st to endDay
61%10%7%11%11%1
1520
December1st to 10thDay
63%7%9%12%9%1
1520
11th to 20thDay
67%10%10%11%2
1928
21st to endDay
79%7%7%43
2794
January1st to 10thNight
73%9%8%5%41
4406
11th to 20thNight
70%6%7%11%42
4416
21st to endNight
72%6%8%8%6%1
4521
February1st to 10thNight
63%10%11%12%4
2470
11th to 20thNight
57%10%12%13%6%2
2404
21st to endNight
60%8%12%11%7%2
1983
March1st to 10thNight
58%9%11%16%6%
2120
11th to 20thNight
55%9%12%16%6%1
1980
21st to endNight
60%9%13%15%2
2156
April1st to 10thNight
57%9%15%13%6%
1800
11th to 20thNight
49%8%17%16%7%3
1762
21st to endNight
48%8%14%21%7%2
1620
May1st to 10thNight
38%8%17%27%8%2
1526
11th to 20thNight
43%7%17%22%7%3
1416
21st to endNight
39%9%21%24%6%
1552
June1st to 10thNight
41%8%17%28%6%1
1440
11th to 20thNight
34%8%23%27%8%
1440
21st to endNight
23%5%19%35%13%4
1440
July1st to 10thNight
16%415%32%25%7%
1400
11th to 20thNight
15%413%27%32%9%
1392
21st to endNight
6%310%35%36%11%
1519
August1st to 10thNight
11%5%16%39%23%6%
1602
11th to 20thNight
13%415%38%22%8%
1602
21st to endNight
18%5%11%37%23%6%
1891
September1st to 10thNight
15%5%14%31%23%11%
1800
11th to 20thNight
29%7%14%25%16%8%
1826
21st to endNight
29%7%16%22%19%8%
2047
October1st to 10thNight
35%6%10%27%18%5%
2160
11th to 20thNight
38%9%12%21%16%3
2160
21st to endNight
46%8%11%17%15%3
2377
November1st to 10thNight
57%9%10%16%7%
2518
11th to 20thNight
62%8%10%11%7%2
2660
21st to endNight
55%8%11%11%13%2
2660
December1st to 10thNight
58%8%11%12%11%1
2660
11th to 20thNight
64%9%9%12%6%
3276
21st to endNight
66%10%11%9%3
4862

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%17%22%18%12%3
180
11th to 20thDay
27%14%16%27%12%4
180
21st to endDay
24%10%19%26%16%5%
407
February1st to 10thDay
25%16%19%21%15%5%
370
11th to 20thDay
27%11%27%19%13%3
365
21st to endDay
21%23%22%18%13%2
334
March1st to 10thDay
21%12%29%25%10%2
449
11th to 20thDay
25%10%24%22%17%2
420
21st to endDay
24%16%21%22%15%2
462
April1st to 10thDay
24%17%22%17%15%5%
420
11th to 20thDay
24%13%25%20%12%6%
412
21st to endDay
17%13%28%23%15%4
420
May1st to 10thDay
13%14%23%24%19%6%
423
11th to 20thDay
20%11%20%23%17%9%
448
21st to endDay
13%9%20%25%22%11%
485
June1st to 10thDay
16%10%19%24%22%9%
450
11th to 20thDay
15%9%25%29%18%3
450
21st to endDay
5%7%19%29%32%8%
450
July1st to 10thDay
4416%34%29%12%
446
11th to 20thDay
2319%32%31%12%
444
21st to endDay
2313%31%38%13%
487
August1st to 10thDay
3212%31%34%18%
447
11th to 20thDay
2310%29%36%21%
437
21st to endDay
5%415%34%30%12%
495
September1st to 10thDay
6%319%30%30%13%
450
11th to 20thDay
9%6%16%28%30%12%
450
21st to endDay
12%6%21%30%25%6%
450
October1st to 10thDay
13%10%21%23%24%10%
450
11th to 20thDay
15%11%17%23%24%10%
450
21st to endDay
19%14%22%25%13%7%
493
November1st to 10thDay
21%13%24%26%13%3
214
11th to 20thDay
19%12%25%19%18%7%
180
21st to endDay
23%11%22%21%18%7%
180
December1st to 10thDay
26%11%16%27%12%7%
180
11th to 20thDay
29%9%19%29%10%3
180
21st to endDay
27%11%24%21%14%3
198
January1st to 10thNight
29%9%21%25%13%3
760
11th to 20thNight
26%9%18%25%18%3
760
21st to endNight
23%6%17%34%18%3
836
February1st to 10thNight
20%7%23%30%18%2
760
11th to 20thNight
22%8%21%31%17%1
744
21st to endNight
22%11%23%32%12%
628
March1st to 10thNight
18%9%23%34%15%1
750
11th to 20thNight
21%6%21%34%16%1
720
21st to endNight
22%8%23%28%17%1
792
April1st to 10thNight
23%8%21%30%17%1
720
11th to 20thNight
18%8%24%33%16%1
694
21st to endNight
16%418%40%21%1
540
May1st to 10thNight
11%425%41%18%1
446
11th to 20thNight
13%417%44%22%1
354
21st to endNight
12%321%39%24%1
389
June1st to 10thNight
14%317%43%23%
360
11th to 20thNight
12%125%44%16%1
360
21st to endNight
8%216%54%21%
360
July1st to 10thNight
4113%56%25%1
350
11th to 20thNight
4121%51%23%
348
21st to endNight
1113%54%31%1
426
August1st to 10thNight
319%45%38%5%
537
11th to 20thNight
47%41%44%3
534
21st to endNight
5%116%45%32%2
703
September1st to 10thNight
5%216%41%35%1
720
11th to 20thNight
7%314%36%33%6%
720
21st to endNight
10%413%40%30%4
720
October1st to 10thNight
12%218%39%25%3
720
11th to 20thNight
15%315%36%26%4
720
21st to endNight
19%6%22%30%18%4
792
November1st to 10thNight
22%6%19%35%17%1
740
11th to 20thNight
25%9%20%29%14%2
760
21st to endNight
20%6%19%34%19%2
760
December1st to 10thNight
24%5%19%33%17%3
760
11th to 20thNight
26%8%24%27%14%1
760
21st to endNight
28%9%23%27%12%1
836
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