Dallas (OR)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dallas (OR) clear sky chart from 2005-11-05 to 2018-02-13.

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
50%
15289
13%
48828
13%
15262
52%
15262
20%
33969

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 15thNight
36%
776
7%
2716
7%
776
38%
776
8%
2212
January16th to endNight
41%
832
11%
2766
11%
832
43%
832
13%
2122
February1st to 15thNight
40%
746
7%
2444
7%
746
41%
746
11%
1988
February16th to endNight
37%
632
9%
2017
7%
632
40%
632
12%
1562
March1st to 15thNight
38%
720
6%
2018
5%
720
39%
720
12%
1668
March16th to endNight
36%
768
7%
2097
5%
768
37%
768
12%
1731
April1st to 15thNight
40%
719
8%
1799
4%
719
42%
719
16%
1424
April16th to endNight
51%
588
12%
1668
9%
588
52%
588
20%
1202
May1st to 15thNight
53%
416
14%
1496
14%
416
57%
416
23%
922
May16th to endNight
54%
375
10%
1496
13%
374
57%
374
17%
973
June1st to 15thNight
56%
360
10%
1440
14%
360
59%
360
19%
896
June16th to endNight
60%
360
14%
1440
19%
360
64%
360
29%
772
July1st to 15thNight
78%
340
20%
1360
30%
340
82%
340
50%
543
July16th to endNight
82%
397
28%
1436
36%
374
88%
374
65%
504
August1st to 15thNight
86%
538
27%
1611
25%
535
87%
535
60%
721
August16th to endNight
79%
646
33%
1792
25%
646
81%
646
55%
892
September1st to 15thNight
78%
720
30%
1800
19%
720
80%
720
61%
936
September16th to endNight
68%
716
26%
1983
23%
716
70%
716
38%
1178
October1st to 15thNight
58%
720
18%
2160
18%
720
62%
720
29%
1359
October16th to endNight
49%
768
14%
2305
14%
768
51%
768
18%
1661
November1st to 15thNight
40%
760
8%
2612
7%
760
41%
760
10%
2091
November16th to endNight
39%
780
7%
2730
7%
780
41%
780
12%
2088
December1st to 15thNight
40%
780
11%
2730
10%
780
42%
780
12%
2077
December16th to endNight
31%
832
6%
2912
6%
832
32%
832
7%
2447

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%8%36%6%35%446%33%
49225
Night
14%7%36%6%35%45%6%36%
48998
Cloud CoverDay
16%8%37%6%35%446%33%
49225
Night
16%7%36%5%34446%36%
49002
TransparencyDay
51%7%11%17%10%2
48899
Night
48%7%12%18%10%2
48829
SeeingDay
17%9%20%25%18%7%
6098
Night
18%416%34%23%2
15300

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 15thDay
23%12%6%10%7%46%435%15%
1552
16th to endDay
22%8%48%8%5%6%5%5%6%19%
1807
February1st to 15thDay
23%12%5%8%8%45%5%45%15%
1685
16th to endDay
20%14%5%8%9%45%5%4416%
1457
March1st to 15thDay
24%13%5%8%8%46%5%45%13%
1941
16th to endDay
24%11%410%9%46%437%12%
2127
April1st to 15thDay
20%12%5%7%10%47%5%6%6%15%
2149
16th to endDay
18%10%48%8%36%5%5%7%21%
2289
May1st to 15thDay
14%9%36%6%33446%34%
2454
16th to endDay
17%7%37%7%46%5%6%7%27%
2615
June1st to 15thDay
16%8%5%7%6%45%446%29%
2520
16th to endDay
10%5%36%7%35%5%5%7%39%
2520
July1st to 15thDay
4213422246%63%
2520
16th to endDay
6%212212235%67%
2633
August1st to 15thDay
33332335%7%62%
2340
16th to endDay
4414313348%60%
2408
September1st to 15thDay
4312314346%62%
2160
16th to endDay
12%6%26%5%34347%42%
1974
October1st to 15thDay
14%8%35%7%45%5%5%6%34%
1800
16th to endDay
16%8%39%9%35%5%5%6%26%
1917
November1st to 15thDay
22%11%5%10%8%45%5%5%8%13%
1573
16th to endDay
20%11%410%8%46%5%5%418%
1560
December1st to 15thDay
20%10%5%9%8%45%5%5%5%19%
1560
16th to endDay
23%12%5%9%9%5%6%5%5%411%
1664
January1st to 15thNight
22%11%5%8%7%46%5%6%5%18%
2716
16th to endNight
18%11%49%6%345%5%6%25%
2766
February1st to 15thNight
16%10%5%8%9%46%6%6%6%20%
2432
16th to endNight
17%9%39%7%46%6%5%425%
2017
March1st to 15thNight
19%10%48%8%37%5%5%6%20%
2018
16th to endNight
20%10%38%8%46%5%6%6%18%
2093
April1st to 15thNight
18%9%37%6%45%5%5%6%26%
1799
16th to endNight
12%6%36%6%45%6%5%8%34%
1668
May1st to 15thNight
9%6%25%5%35%5%5%7%42%
1496
16th to endNight
12%5%36%6%446%7%8%35%
1496
June1st to 15thNight
12%5%36%5%25%347%43%
1440
16th to endNight
6%6%25%5%24346%52%
1440
July1st to 15thNight
2212212325%73%
1440
16th to endNight
3111113480%
1533
August1st to 15thNight
112212246%73%
1620
16th to endNight
421231332471%
1792
September1st to 15thNight
31121324473%
1800
16th to endNight
9%414323448%52%
1983
October1st to 15thNight
11%5%25%42445%7%47%
2160
16th to endNight
16%6%37%6%35%5%5%434%
2305
November1st to 15thNight
21%8%49%7%36%5%6%5%21%
2612
16th to endNight
20%9%37%7%36%5%46%25%
2730
December1st to 15thNight
20%9%37%6%46%45%6%26%
2730
16th to endNight
24%11%5%8%9%35%5%4417%
2912

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 15thDay
25%12%6%11%8%45%33314%
1552
16th to endDay
23%9%48%6%46%5%46%18%
1807
February1st to 15thDay
24%12%48%7%46%5%45%14%
1685
16th to endDay
21%12%6%10%8%5%6%44317%
1457
March1st to 15thDay
25%12%5%9%8%37%5%45%13%
1941
16th to endDay
25%11%5%9%8%46%435%14%
2127
April1st to 15thDay
20%11%5%8%8%5%6%5%5%6%17%
2149
16th to endDay
19%9%47%7%46%5%5%6%23%
2289
May1st to 15thDay
16%8%36%5%3435%7%35%
2454
16th to endDay
18%7%36%7%36%5%5%8%27%
2615
June1st to 15thDay
17%7%5%7%6%35%5%45%30%
2520
16th to endDay
10%5%35%6%35%5%5%7%41%
2520
July1st to 15thDay
4313223347%63%
2520
16th to endDay
6%313212225%68%
2633
August1st to 15thDay
3312323347%62%
2340
16th to endDay
4413312347%61%
2408
September1st to 15thDay
5%312323346%62%
2160
16th to endDay
13%6%26%5%34447%41%
1974
October1st to 15thDay
16%7%36%6%35%45%6%32%
1800
16th to endDay
17%10%48%7%46%446%24%
1917
November1st to 15thDay
25%10%5%9%6%47%5%5%5%12%
1573
16th to endDay
22%12%5%9%7%5%5%44418%
1560
December1st to 15thDay
21%12%5%9%8%34445%18%
1560
16th to endDay
26%13%6%11%7%45%5%5%410%
1664
January1st to 15thNight
24%11%5%7%6%45%5%45%18%
2716
16th to endNight
21%9%47%6%3445%6%25%
2766
February1st to 15thNight
18%11%5%8%8%36%45%5%21%
2432
16th to endNight
18%9%48%6%45%5%45%26%
2017
March1st to 15thNight
20%9%48%7%46%5%46%21%
2018
16th to endNight
21%10%48%8%45%5%6%6%19%
2097
April1st to 15thNight
20%8%37%6%35%45%7%27%
1799
16th to endNight
14%6%35%6%45%45%8%34%
1668
May1st to 15thNight
10%5%26%445%5%5%7%43%
1496
16th to endNight
13%5%36%6%25%6%6%8%35%
1496
June1st to 15thNight
14%5%35%425%25%6%43%
1440
16th to endNight
7%7%24423347%52%
1440
July1st to 15thNight
321221223473%
1440
16th to endNight
2111112480%
1533
August1st to 15thNight
2111212246%72%
1620
16th to endNight
321221322371%
1792
September1st to 15thNight
312213325%73%
1800
16th to endNight
9%41332445%7%53%
1983
October1st to 15thNight
12%5%15%33445%6%46%
2160
16th to endNight
17%7%26%6%34445%35%
2305
November1st to 15thNight
25%7%47%7%45%5%6%5%21%
2612
16th to endNight
22%8%38%7%45%445%25%
2730
December1st to 15thNight
21%9%47%7%3445%6%25%
2730
16th to endNight
25%11%5%9%8%46%5%4416%
2912

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 15thDay
74%5%7%8%4
1552
16th to endDay
64%7%9%10%6%2
1807
February1st to 15thDay
71%8%8%8%3
1685
16th to endDay
70%7%6%8%6%
1457
March1st to 15thDay
72%6%9%8%3
1941
16th to endDay
71%8%9%8%2
2127
April1st to 15thDay
67%8%11%9%2
2149
16th to endDay
60%10%11%11%41
2289
May1st to 15thDay
49%6%12%20%10%1
2454
16th to endDay
53%10%14%16%4
2619
June1st to 15thDay
54%8%14%16%4
2520
16th to endDay
41%8%18%21%7%2
2520
July1st to 15thDay
21%5%13%29%22%6%
2371
16th to endDay
18%410%29%29%7%
2468
August1st to 15thDay
21%6%15%32%18%5%
2324
16th to endDay
23%5%12%31%21%4
2408
September1st to 15thDay
21%5%12%25%24%10%
2160
16th to endDay
41%6%15%21%12%3
1974
October1st to 15thDay
49%8%9%17%12%2
1800
16th to endDay
58%8%9%11%10%1
1917
November1st to 15thDay
68%7%10%10%2
1573
16th to endDay
67%8%6%9%7%
1560
December1st to 15thDay
66%6%7%11%6%
1560
16th to endDay
74%7%7%6%3
1664
January1st to 15thNight
67%6%9%8%6%1
2716
16th to endNight
59%6%9%11%9%3
2766
February1st to 15thNight
62%9%11%12%4
2444
16th to endNight
58%8%11%12%7%1
2017
March1st to 15thNight
63%9%9%13%4
2018
16th to endNight
62%9%12%11%3
2097
April1st to 15thNight
57%8%15%12%6%
1799
16th to endNight
48%8%15%19%6%1
1668
May1st to 15thNight
40%6%15%25%9%2
1497
16th to endNight
45%8%19%20%5%
1496
June1st to 15thNight
41%8%18%23%7%
1440
16th to endNight
32%5%21%29%8%2
1440
July1st to 15thNight
15%314%32%25%7%
1360
16th to endNight
9%212%31%32%11%
1436
August1st to 15thNight
13%416%39%18%7%
1611
16th to endNight
18%312%35%23%6%
1792
September1st to 15thNight
14%5%13%26%27%11%
1800
16th to endNight
29%6%15%25%16%6%
1983
October1st to 15thNight
36%7%10%25%15%4
2160
16th to endNight
50%7%11%15%12%1
2305
November1st to 15thNight
62%8%10%13%4
2612
16th to endNight
59%7%11%9%11%1
2730
December1st to 15thNight
59%6%10%13%9%
2730
16th to endNight
71%6%8%9%3
2912

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 15thDay
27%5%16%25%21%3
90
16th to endDay
27%9%18%22%16%5%
239
February1st to 15thDay
30%12%17%21%15%2
273
16th to endDay
25%16%25%19%10%3
217
March1st to 15thDay
34%15%26%16%5%1
270
16th to endDay
33%14%22%18%9%1
288
April1st to 15thDay
21%14%25%18%13%7%
269
16th to endDay
24%14%26%18%10%5%
270
May1st to 15thDay
19%18%24%18%14%4
288
16th to endDay
16%8%20%24%16%13%
330
June1st to 15thDay
18%9%23%23%20%5%
315
16th to endDay
9%10%22%30%21%5%
315
July1st to 15thDay
45%15%32%30%12%
305
16th to endDay
4319%37%27%9%
327
August1st to 15thDay
3414%33%27%15%
315
16th to endDay
5%413%28%31%15%
332
September1st to 15thDay
6%420%26%28%13%
315
16th to endDay
12%7%20%29%26%3
315
October1st to 15thDay
18%11%20%24%20%4
315
16th to endDay
22%12%18%26%14%6%
333
November1st to 15thDay
26%14%23%25%5%2
101
16th to endDay
27%12%26%14%14%4
90
December1st to 15thDay
31%5%21%23%10%8%
90
16th to endDay
28%6%19%27%14%4
96
January1st to 15thNight
28%7%16%26%19%2
780
16th to endNight
23%5%15%29%21%3
832
February1st to 15thNight
21%5%19%31%21%1
752
16th to endNight
21%8%22%30%15%
632
March1st to 15thNight
23%7%20%32%14%1
720
16th to endNight
24%7%19%30%16%1
768
April1st to 15thNight
24%6%20%27%19%1
719
16th to endNight
15%417%38%22%1
588
May1st to 15thNight
12%323%41%19%
417
16th to endNight
14%215%39%26%1
375
June1st to 15thNight
15%215%43%23%
360
16th to endNight
11%120%47%19%
360
July1st to 15thNight
412%51%30%
340
16th to endNight
211%52%31%
397
August1st to 15thNight
45%40%43%5%
538
16th to endNight
6%8%40%42%1
646
September1st to 15thNight
4112%36%40%5%
720
16th to endNight
10%211%39%32%3
716
October1st to 15thNight
15%117%37%24%3
720
16th to endNight
21%317%31%22%4
768
November1st to 15thNight
26%6%16%35%15%
760
16th to endNight
24%8%16%30%16%2
780
December1st to 15thNight
25%419%31%17%2
780
16th to endNight
28%7%20%26%15%
832
Page generated at 2018-02-13 17:46:04. Version ac04

Copyright 2018 A. Danko


Dallas (OR) Clear Sky Chart |Charts Home