Prineville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prineville 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
54%
22889
17%
80706
18%
22805
57%
22805
24%
51218

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
35%
750
7%
4377
8%
736
38%
736
7%
3274
January11th to 20thNight
42%
755
10%
4412
13%
740
47%
740
9%
3398
January21st to endNight
45%
832
9%
4677
15%
814
50%
814
10%
3311
February1st to 10thNight
39%
760
11%
2470
11%
760
42%
760
17%
1784
February11th to 20thNight
45%
741
14%
2379
12%
740
50%
740
20%
1634
February21st to endNight
39%
628
14%
1884
12%
628
43%
628
16%
1405
March1st to 10thNight
39%
750
12%
2249
11%
750
42%
750
18%
1643
March11th to 20thNight
46%
720
14%
1988
12%
720
48%
720
21%
1430
March21st to endNight
39%
792
10%
2063
6%
792
41%
792
18%
1582
April1st to 10thNight
43%
720
13%
1800
7%
720
44%
720
22%
1310
April11th to 20thNight
45%
711
16%
1779
9%
711
47%
711
24%
1283
April21st to endNight
50%
665
15%
1745
10%
665
52%
665
27%
1193
May1st to 10thNight
59%
360
19%
1440
22%
360
63%
360
27%
789
May11th to 20thNight
62%
354
17%
1416
21%
354
66%
354
24%
809
May21st to endNight
60%
388
13%
1552
17%
388
64%
388
20%
938
June1st to 10thNight
59%
360
13%
1440
19%
360
63%
360
24%
834
June11th to 20thNight
59%
360
18%
1440
26%
360
65%
360
32%
721
June21st to endNight
74%
360
23%
1440
38%
360
78%
360
46%
609
July1st to 10thNight
84%
350
23%
1400
36%
350
88%
350
59%
512
July11th to 20thNight
83%
348
32%
1392
46%
348
89%
348
64%
479
July21st to endNight
84%
394
38%
1488
51%
372
89%
372
65%
506
August1st to 10thNight
86%
435
34%
1501
36%
433
88%
433
59%
602
August11th to 20thNight
87%
564
36%
1632
28%
564
89%
564
68%
707
August21st to endNight
78%
792
39%
1980
25%
792
80%
792
71%
945
September1st to 10thNight
80%
720
39%
1800
24%
720
82%
720
71%
859
September11th to 20thNight
74%
720
35%
1800
25%
720
75%
720
52%
1001
September21st to endNight
69%
720
30%
2020
27%
720
71%
720
43%
1130
October1st to 10thNight
65%
720
22%
2160
22%
720
68%
720
38%
1224
October11th to 20thNight
61%
720
25%
2160
24%
720
65%
720
36%
1232
October21st to endNight
54%
792
20%
2483
20%
792
58%
792
26%
1570
November1st to 10thNight
47%
740
17%
2405
18%
740
49%
740
18%
1690
November11th to 20thNight
43%
760
13%
2615
12%
760
45%
760
17%
1829
November21st to endNight
49%
760
14%
2660
13%
760
54%
760
23%
1676
December1st to 10thNight
46%
760
13%
2660
12%
760
49%
760
19%
1777
December11th to 20thNight
40%
759
11%
3204
10%
759
44%
759
12%
2302
December21st to endNight
33%
829
7%
4795
9%
817
36%
817
8%
3230

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
10%8%36%5%3445%6%45%
78501
Night
11%10%36%5%35%45%7%41%
81090
TransparencyDay
39%411%21%17%8%
78204
Night
43%413%21%14%5%
80908
SeeingDay
14%10%25%27%18%7%
13675
Night
14%6%17%39%22%3
22920

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
15%15%48%8%46%5%6%7%20%
2539
11th to 20thDay
22%16%48%6%35%5%45%21%
2540
21st to endDay
15%13%5%9%7%45%5%6%6%25%
2956
February1st to 10thDay
12%13%47%7%446%5%9%29%
1710
11th to 20thDay
11%13%49%6%345%6%7%32%
1689
21st to endDay
11%14%5%8%6%46%6%6%7%26%
1570
March1st to 10thDay
11%13%6%9%6%46%5%5%8%26%
1871
11th to 20thDay
13%13%48%6%35%5%6%8%30%
1970
21st to endDay
12%14%5%9%7%46%5%6%6%26%
2292
April1st to 10thDay
12%15%5%8%7%35%5%46%28%
2160
11th to 20thDay
11%12%5%7%6%3435%7%36%
2129
21st to endDay
8%10%36%6%25%5%6%8%41%
2213
May1st to 10thDay
9%8%35%435%46%7%46%
2520
11th to 20thDay
11%8%37%5%35%5%6%6%41%
2477
21st to endDay
13%9%35%5%345%6%7%40%
2723
June1st to 10thDay
13%7%35%6%35%5%5%7%42%
2520
11th to 20thDay
9%5%35%43445%7%52%
2520
21st to endDay
4312423345%67%
2520
July1st to 10thDay
2212213335%75%
2520
11th to 20thDay
321231223477%
2520
21st to endDay
211221233480%
2741
August1st to 10thDay
2112323346%72%
2428
11th to 20thDay
2113222335%76%
2267
21st to endDay
3212213235%76%
2376
September1st to 10thDay
2212212346%76%
2160
11th to 20thDay
5%42433345%7%60%
2160
21st to endDay
8%6%2342445%6%57%
1939
October1st to 10thDay
10%7%25%425%446%51%
1800
11th to 20thDay
11%6%25%5%3446%7%47%
1800
21st to endDay
13%8%26%6%345%45%44%
1872
November1st to 10thDay
14%10%47%7%35%5%5%8%32%
1674
11th to 20thDay
17%10%27%6%45%6%6%7%28%
1563
21st to endDay
13%11%37%5%35%5%6%9%34%
1520
December1st to 10thDay
13%10%46%5%35%5%5%8%36%
1520
11th to 20thDay
14%11%47%8%45%7%7%8%26%
1928
21st to endDay
13%13%5%9%7%45%5%5%7%26%
2794
January1st to 10thNight
14%15%5%9%7%5%6%6%6%8%21%
4406
11th to 20thNight
21%17%47%7%45%5%5%5%21%
4420
21st to endNight
16%14%48%7%45%5%6%7%24%
4703
February1st to 10thNight
12%12%5%8%7%46%46%7%29%
2470
11th to 20thNight
11%13%47%435%45%7%35%
2377
21st to endNight
11%15%5%7%7%5%5%5%5%7%27%
1884
March1st to 10thNight
12%13%6%8%6%35%5%6%7%30%
2249
11th to 20thNight
10%11%49%7%46%5%7%8%30%
1988
21st to endNight
10%14%5%8%7%46%6%7%7%27%
2063
April1st to 10thNight
12%13%47%7%35%5%6%7%32%
1800
11th to 20thNight
12%12%46%5%35%447%37%
1779
21st to endNight
10%10%36%5%35%5%6%9%38%
1745
May1st to 10thNight
7%7%25%5%25%46%8%48%
1440
11th to 20thNight
10%5%345%35%5%5%9%45%
1416
21st to endNight
11%7%36%6%345%6%9%41%
1552
June1st to 10thNight
14%6%24435%5%5%6%47%
1440
11th to 20thNight
8%425%423448%55%
1440
21st to endNight
5%313223346%68%
1440
July1st to 10thNight
2111223446%75%
1440
11th to 20thNight
1112112335%80%
1440
21st to endNight
111211133481%
1576
August1st to 10thNight
1112323346%74%
1509
11th to 20thNight
1112213335%77%
1632
21st to endNight
1212212335%79%
1980
September1st to 10thNight
3112212235%78%
1800
11th to 20thNight
5%324423446%63%
1800
21st to endNight
7%5%24333446%59%
2020
October1st to 10thNight
10%6%24423346%56%
2160
11th to 20thNight
11%5%2432445%7%53%
2160
21st to endNight
12%8%26%6%3445%6%44%
2483
November1st to 10thNight
15%10%37%6%35%5%46%34%
2405
11th to 20thNight
17%10%36%7%46%5%5%7%30%
2615
21st to endNight
12%10%46%435%46%8%38%
2660
December1st to 10thNight
12%11%47%6%35%45%8%35%
2660
11th to 20thNight
13%14%48%8%46%6%6%7%25%
3276
21st to endNight
13%13%48%7%45%5%5%6%29%
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
62%6%14%15%3
2539
11th to 20thDay
65%313%13%42
2540
21st to endDay
59%414%16%5%1
2956
February1st to 10thDay
52%7%15%20%6%
1710
11th to 20thDay
50%7%13%19%9%2
1698
21st to endDay
54%7%15%16%7%1
1570
March1st to 10thDay
55%5%13%17%8%1
1871
11th to 20thDay
52%5%12%24%7%
1970
21st to endDay
57%6%13%17%6%
2292
April1st to 10thDay
55%6%10%17%10%1
2160
11th to 20thDay
49%5%11%19%12%4
2132
21st to endDay
41%5%12%27%12%3
2213
May1st to 10thDay
37%5%12%28%17%1
2520
11th to 20thDay
43%5%10%27%13%3
2480
21st to endDay
43%5%13%24%13%1
2724
June1st to 10thDay
42%410%29%13%1
2520
11th to 20thDay
33%410%31%19%3
2520
21st to endDay
21%29%27%30%11%
2520
July1st to 10thDay
14%37%22%27%27%
2451
11th to 20thDay
13%26%15%31%33%
2445
21st to endDay
10%2213%39%33%
2589
August1st to 10thDay
15%35%24%33%19%
2411
11th to 20thDay
14%25%22%35%22%
2267
21st to endDay
13%3424%38%18%
2376
September1st to 10thDay
12%2426%33%23%
2160
11th to 20thDay
25%37%24%27%14%
2160
21st to endDay
29%49%25%23%10%
1939
October1st to 10thDay
36%5%9%20%22%9%
1800
11th to 20thDay
36%314%23%19%6%
1800
21st to endDay
42%5%11%21%18%3
1872
November1st to 10thDay
50%412%24%11%1
1674
11th to 20thDay
52%7%16%18%8%
1563
21st to endDay
47%5%15%17%14%1
1520
December1st to 10thDay
47%7%14%23%8%1
1520
11th to 20thDay
55%5%19%17%4
1928
21st to endDay
57%5%14%20%31
2794
January1st to 10thNight
63%5%15%12%5%
4406
11th to 20thNight
65%411%12%5%3
4420
21st to endNight
59%317%14%6%
4703
February1st to 10thNight
54%6%16%16%8%
2470
11th to 20thNight
47%7%15%20%9%2
2379
21st to endNight
55%6%10%20%7%1
1884
March1st to 10thNight
52%7%11%20%8%2
2249
11th to 20thNight
50%5%15%22%6%1
1988
21st to endNight
55%8%14%18%5%
2063
April1st to 10thNight
50%6%16%19%9%1
1800
11th to 20thNight
48%6%13%20%12%1
1779
21st to endNight
43%6%14%25%10%2
1745
May1st to 10thNight
35%414%30%15%
1440
11th to 20thNight
38%417%27%11%2
1416
21st to endNight
42%5%16%25%10%1
1552
June1st to 10thNight
38%5%13%31%12%1
1440
11th to 20thNight
29%5%14%35%14%3
1440
21st to endNight
20%311%33%25%7%
1440
July1st to 10thNight
12%312%26%28%20%
1400
11th to 20thNight
10%27%19%34%28%
1392
21st to endNight
10%2217%40%29%
1488
August1st to 10thNight
14%36%29%35%14%
1501
11th to 20thNight
11%28%26%35%18%
1632
21st to endNight
11%26%27%38%15%
1980
September1st to 10thNight
12%25%28%35%19%
1800
11th to 20thNight
23%38%26%26%14%
1800
21st to endNight
28%38%24%24%13%
2020
October1st to 10thNight
31%411%23%25%7%
2160
11th to 20thNight
32%414%23%22%5%
2160
21st to endNight
41%5%12%19%19%3
2483
November1st to 10thNight
52%5%9%18%14%2
2405
11th to 20thNight
52%6%13%21%8%
2615
21st to endNight
44%415%20%17%1
2660
December1st to 10thNight
47%6%17%20%9%1
2660
11th to 20thNight
57%415%17%6%
3276
21st to endNight
56%414%20%5%1
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
34%7%27%18%12%1
180
11th to 20thDay
21%11%29%24%11%3
180
21st to endDay
18%12%27%27%14%1
295
February1st to 10thDay
23%13%26%25%12%1
370
11th to 20thDay
19%15%31%23%11%1
377
21st to endDay
20%13%27%29%10%1
382
March1st to 10thDay
21%14%29%28%8%1
449
11th to 20thDay
19%15%26%26%12%2
420
21st to endDay
23%15%26%25%11%1
462
April1st to 10thDay
24%16%24%22%10%4
420
11th to 20thDay
19%14%28%23%10%5%
412
21st to endDay
14%19%26%23%14%4
420
May1st to 10thDay
16%14%25%25%16%3
423
11th to 20thDay
21%13%22%20%18%7%
448
21st to endDay
14%9%21%26%20%9%
485
June1st to 10thDay
14%11%23%22%19%11%
450
11th to 20thDay
11%14%30%25%17%4
450
21st to endDay
47%20%34%23%11%
450
July1st to 10thDay
36%28%33%21%10%
446
11th to 20thDay
29%26%28%25%10%
444
21st to endDay
35%28%26%25%12%
487
August1st to 10thDay
45%23%29%24%15%
447
11th to 20thDay
2420%30%26%18%
437
21st to endDay
5%6%22%27%26%13%
495
September1st to 10thDay
35%22%30%28%12%
450
11th to 20thDay
7%7%20%31%28%7%
450
21st to endDay
11%8%19%29%26%8%
450
October1st to 10thDay
14%9%22%28%20%8%
450
11th to 20thDay
15%9%20%27%22%8%
450
21st to endDay
18%7%26%24%21%5%
387
November1st to 10thDay
17%9%25%35%13%1
270
11th to 20thDay
18%10%26%29%14%2
201
21st to endDay
17%12%23%33%12%2
180
December1st to 10thDay
22%8%32%23%9%6%
180
11th to 20thDay
24%7%33%29%7%
180
21st to endDay
20%10%26%28%13%3
198
January1st to 10thNight
21%9%24%29%16%2
760
11th to 20thNight
20%9%20%29%20%2
760
21st to endNight
18%6%17%39%17%3
836
February1st to 10thNight
17%8%21%37%15%1
760
11th to 20thNight
17%7%20%40%15%2
744
21st to endNight
18%10%19%39%13%1
628
March1st to 10thNight
17%11%22%35%14%1
750
11th to 20thNight
16%8%18%38%19%2
720
21st to endNight
16%10%22%36%15%1
792
April1st to 10thNight
19%8%18%34%18%2
720
11th to 20thNight
17%8%21%33%18%3
711
21st to endNight
16%8%19%36%19%2
665
May1st to 10thNight
12%5%16%44%22%1
360
11th to 20thNight
13%5%12%44%25%2
354
21st to endNight
14%412%39%27%3
389
June1st to 10thNight
15%313%45%21%2
360
11th to 20thNight
11%418%44%21%1
360
21st to endNight
6%214%50%28%1
360
July1st to 10thNight
3110%49%36%1
350
11th to 20thNight
211%59%26%2
348
21st to endNight
210%52%35%2
394
August1st to 10thNight
215%49%39%4
435
11th to 20thNight
215%39%45%9%
564
21st to endNight
2213%46%32%4
792
September1st to 10thNight
3212%44%35%4
720
11th to 20thNight
5%310%40%33%9%
720
21st to endNight
10%411%39%31%5%
720
October1st to 10thNight
12%311%41%28%4
720
11th to 20thNight
13%416%38%25%4
720
21st to endNight
15%5%16%40%20%4
792
November1st to 10thNight
19%5%17%41%15%1
740
11th to 20thNight
19%7%20%36%16%2
760
21st to endNight
18%9%17%36%17%3
760
December1st to 10thNight
19%5%18%35%20%2
760
11th to 20thNight
21%6%21%35%15%2
760
21st to endNight
24%10%22%31%11%1
836
Page generated at 2024-03-05 04:23:58. Version ac07

Copyright © 2024 Attilla Danko.


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