Stayton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stayton 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
45%
15299
13%
48829
12%
15272
47%
15272
18%
34968

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
33%
777
7%
2716
7%
776
35%
776
8%
2240
January16th to endNight
35%
832
11%
2782
11%
832
36%
832
11%
2181
February1st to 15thNight
35%
747
6%
2444
7%
747
36%
747
10%
2002
February16th to endNight
30%
632
10%
2001
7%
632
34%
632
11%
1581
March1st to 15thNight
29%
720
4%
2035
3%
720
30%
720
10%
1686
March16th to endNight
29%
768
6%
2085
4%
768
30%
768
10%
1764
April1st to 15thNight
33%
719
6%
1799
3%
719
34%
719
13%
1497
April16th to endNight
45%
612
9%
1692
6%
612
46%
612
17%
1290
May1st to 15thNight
43%
401
12%
1481
11%
401
48%
401
19%
970
May16th to endNight
47%
375
8%
1496
11%
374
48%
374
12%
1079
June1st to 15thNight
43%
360
8%
1440
10%
360
48%
360
15%
977
June16th to endNight
53%
360
12%
1440
19%
360
56%
360
24%
838
July1st to 15thNight
71%
340
19%
1360
25%
340
79%
340
45%
566
July16th to endNight
73%
379
30%
1419
35%
357
84%
357
59%
514
August1st to 15thNight
81%
538
28%
1611
24%
535
84%
535
57%
743
August16th to endNight
74%
663
34%
1809
22%
663
77%
663
56%
910
September1st to 15thNight
71%
720
30%
1800
18%
720
74%
720
56%
966
September16th to endNight
64%
716
26%
1976
22%
716
66%
716
35%
1214
October1st to 15thNight
51%
720
16%
2160
16%
720
54%
720
25%
1430
October16th to endNight
44%
768
15%
2321
15%
768
46%
768
17%
1705
November1st to 15thNight
31%
760
8%
2590
8%
760
32%
760
9%
2117
November16th to endNight
37%
780
7%
2730
8%
780
38%
780
11%
2136
December1st to 15thNight
39%
780
10%
2730
10%
780
40%
780
13%
2065
December16th to endNight
29%
832
5%
2912
6%
832
30%
832
7%
2497

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
23%7%35%424445%34%
49229
Night
24%7%35%424345%35%
48998
Cloud CoverDay
24%7%25%423345%35%
49229
Night
26%7%25%423345%35%
49002
TransparencyDay
51%6%11%16%11%2
48901
Night
52%5%11%16%10%3
48830
SeeingDay
27%8%23%25%12%2
6075
Night
29%414%30%19%1
15308

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
39%9%45%5%3335%316%
1552
16th to endDay
32%8%35%425%35%7%19%
1791
February1st to 15thDay
34%11%35%5%25%345%16%
1685
16th to endDay
32%11%47%5%23445%17%
1472
March1st to 15thDay
38%10%47%5%24335%13%
1923
16th to endDay
35%11%37%5%25%33415%
2139
April1st to 15thDay
30%10%5%7%7%44345%16%
2149
16th to endDay
25%8%36%6%34447%23%
2268
May1st to 15thDay
22%7%36%5%23346%34%
2469
16th to endDay
24%7%36%5%35%5%46%26%
2615
June1st to 15thDay
24%7%35%5%3444430%
2520
16th to endDay
14%6%25%5%35%446%42%
2520
July1st to 15thDay
6%312212345%66%
2520
16th to endDay
6%21211222471%
2652
August1st to 15thDay
3213314336%65%
2340
16th to endDay
5%412322337%63%
2393
September1st to 15thDay
6%33212336%66%
2160
16th to endDay
17%6%25%423435%43%
1980
October1st to 15thDay
21%6%2443345%6%36%
1800
16th to endDay
27%8%35%5%335%5%6%26%
1902
November1st to 15thDay
39%8%35%5%2435%6%14%
1595
16th to endDay
32%9%47%6%246%5%417%
1560
December1st to 15thDay
30%9%46%5%24445%22%
1560
16th to endDay
42%11%24324435%13%
1664
January1st to 15thNight
35%8%36%5%26%44417%
2716
16th to endNight
31%9%46%424335%23%
2782
February1st to 15thNight
31%9%45%6%24445%20%
2432
16th to endNight
31%10%36%41443425%
2001
March1st to 15thNight
35%9%445%2334420%
2035
16th to endNight
32%11%46%5%24445%17%
2081
April1st to 15thNight
29%10%46%5%24445%22%
1799
16th to endNight
22%8%35%425%448%30%
1692
May1st to 15thNight
16%5%27%5%24347%38%
1481
16th to endNight
22%8%245%345%5%7%29%
1496
June1st to 15thNight
19%6%46%5%24436%37%
1440
16th to endNight
12%6%26%5%2333448%
1440
July1st to 15thNight
421222223470%
1440
16th to endNight
3211112479%
1515
August1st to 15thNight
2312212335%72%
1620
16th to endNight
5%21121222472%
1809
September1st to 15thNight
5%21221222471%
1800
16th to endNight
12%423423446%51%
1976
October1st to 15thNight
18%6%25%423345%43%
2160
16th to endNight
25%7%2443434435%
2321
November1st to 15thNight
34%8%35%5%34445%19%
2590
16th to endNight
34%7%35%43443425%
2730
December1st to 15thNight
31%9%36%413336%26%
2730
16th to endNight
37%11%46%5%3433415%
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
40%9%25%5%2423320%
1552
16th to endDay
36%8%24324346%23%
1791
February1st to 15thDay
35%11%35%5%24445%18%
1685
16th to endDay
33%12%37%5%2233419%
1472
March1st to 15thDay
40%11%36%424335%13%
1923
16th to endDay
38%11%46%5%24335%14%
2139
April1st to 15thDay
32%11%47%7%3434416%
2149
16th to endDay
28%9%37%5%24345%23%
2268
May1st to 15thDay
23%7%36%423346%34%
2469
16th to endDay
27%6%36%5%3445%5%26%
2615
June1st to 15thDay
27%7%36%5%2444430%
2520
16th to endDay
16%5%25%425%346%41%
2520
July1st to 15thDay
6%212212345%66%
2520
16th to endDay
7%31221212471%
2652
August1st to 15thDay
423314247%64%
2340
16th to endDay
6%412213336%64%
2393
September1st to 15thDay
7%21221346%65%
2160
16th to endDay
19%6%25%5%23336%42%
1980
October1st to 15thDay
24%6%2442445%5%37%
1800
16th to endDay
29%7%15%5%33345%30%
1902
November1st to 15thDay
41%7%35%423345%17%
1595
16th to endDay
36%9%25%43445%419%
1560
December1st to 15thDay
31%10%36%5%14345%23%
1560
16th to endDay
43%10%24314445%15%
1664
January1st to 15thNight
36%8%35%5%24445%18%
2716
16th to endNight
33%10%36%423335%24%
2782
February1st to 15thNight
32%10%36%5%23436%20%
2432
16th to endNight
32%11%36%32333424%
2001
March1st to 15thNight
36%11%34424345%19%
2035
16th to endNight
34%11%46%5%23435%17%
2085
April1st to 15thNight
31%11%36%5%24345%20%
1799
16th to endNight
25%8%34424446%30%
1692
May1st to 15thNight
18%6%27%424247%37%
1481
16th to endNight
25%7%25%435%5%47%28%
1496
June1st to 15thNight
20%6%36%434345%37%
1440
16th to endNight
13%5%26%5%1434348%
1440
July1st to 15thNight
5%3221233370%
1440
16th to endNight
31111212478%
1515
August1st to 15thNight
2213222235%72%
1620
16th to endNight
6%212111225%72%
1809
September1st to 15thNight
6%21221122471%
1800
16th to endNight
14%31332435%6%50%
1976
October1st to 15thNight
20%5%16%42334443%
2160
16th to endNight
27%7%2443334435%
2321
November1st to 15thNight
37%8%25%5%2444419%
2590
16th to endNight
36%6%25%42343425%
2730
December1st to 15thNight
33%8%34323335%27%
2730
16th to endNight
38%11%35%42334417%
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
70%6%8%8%5%1
1552
16th to endDay
62%6%9%10%6%4
1791
February1st to 15thDay
68%7%10%8%4
1685
16th to endDay
69%7%6%8%6%1
1472
March1st to 15thDay
74%5%7%8%3
1923
16th to endDay
74%5%9%7%2
2139
April1st to 15thDay
71%5%11%8%2
2149
16th to endDay
62%7%13%10%5%1
2268
May1st to 15thDay
51%412%21%8%
2469
16th to endDay
58%8%14%15%3
2619
June1st to 15thDay
56%6%14%16%4
2520
16th to endDay
42%6%17%23%7%2
2520
July1st to 15thDay
21%413%28%25%7%
2371
16th to endDay
18%38%26%33%9%
2485
August1st to 15thDay
20%5%16%30%20%6%
2324
16th to endDay
21%5%10%32%24%5%
2393
September1st to 15thDay
20%311%28%23%11%
2160
16th to endDay
44%5%12%18%14%3
1980
October1st to 15thDay
48%6%11%18%10%3
1800
16th to endDay
57%8%10%11%11%1
1902
November1st to 15thDay
69%7%10%10%2
1595
16th to endDay
67%8%8%6%8%
1560
December1st to 15thDay
63%7%7%11%9%1
1560
16th to endDay
71%6%9%7%4
1664
January1st to 15thNight
67%7%8%8%5%2
2716
16th to endNight
64%47%9%8%4
2782
February1st to 15thNight
66%6%10%9%41
2444
16th to endNight
63%5%10%10%7%2
2001
March1st to 15thNight
68%5%10%10%4
2035
16th to endNight
69%5%11%10%3
2085
April1st to 15thNight
65%6%12%9%4
1799
16th to endNight
55%7%16%14%5%1
1692
May1st to 15thNight
47%413%21%8%3
1482
16th to endNight
55%7%16%15%41
1496
June1st to 15thNight
49%8%15%20%6%
1440
16th to endNight
39%418%26%8%2
1440
July1st to 15thNight
18%314%28%26%8%
1360
16th to endNight
12%28%28%35%12%
1419
August1st to 15thNight
16%313%38%20%7%
1611
16th to endNight
17%311%37%22%7%
1809
September1st to 15thNight
19%311%28%22%14%
1800
16th to endNight
34%5%13%23%14%7%
1976
October1st to 15thNight
44%5%9%20%15%4
2160
16th to endNight
53%6%9%13%14%2
2321
November1st to 15thNight
67%6%9%10%6%
2590
16th to endNight
62%6%8%8%10%3
2730
December1st to 15thNight
60%5%9%13%10%1
2730
16th to endNight
72%6%8%7%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
41%318%20%13%3
90
16th to endDay
46%6%12%20%13%1
223
February1st to 15thDay
43%5%21%20%8%
273
16th to endDay
36%13%25%17%6%
220
March1st to 15thDay
52%10%18%14%4
270
16th to endDay
45%12%24%13%4
288
April1st to 15thDay
38%11%21%17%7%2
269
16th to endDay
37%15%24%13%8%1
270
May1st to 15thDay
27%15%26%21%6%1
288
16th to endDay
28%8%17%26%14%4
330
June1st to 15thDay
26%8%26%25%12%1
315
16th to endDay
15%7%27%34%12%1
315
July1st to 15thDay
6%8%24%39%17%3
305
16th to endDay
5%5%29%42%12%4
327
August1st to 15thDay
4329%37%19%4
315
16th to endDay
46%27%34%21%5%
332
September1st to 15thDay
8%7%28%32%19%2
315
16th to endDay
24%8%22%29%14%
315
October1st to 15thDay
30%6%25%24%13%
315
16th to endDay
33%6%19%19%16%4
318
November1st to 15thDay
43%14%16%17%6%
106
16th to endDay
46%8%21%11%10%2
90
December1st to 15thDay
47%416%15%7%7%
90
16th to endDay
48%6%12%15%15%1
96
January1st to 15thNight
40%5%12%22%17%2
780
16th to endNight
37%411%26%16%2
832
February1st to 15thNight
36%313%27%17%1
752
16th to endNight
39%6%16%23%13%
632
March1st to 15thNight
42%5%15%22%12%
720
16th to endNight
38%6%16%24%12%1
768
April1st to 15thNight
36%6%15%25%15%
719
16th to endNight
28%415%29%19%1
612
May1st to 15thNight
20%323%33%17%1
402
16th to endNight
28%311%30%23%2
375
June1st to 15thNight
21%418%37%16%
360
16th to endNight
16%219%41%19%
360
July1st to 15thNight
5%315%48%26%
340
16th to endNight
4117%52%22%
379
August1st to 15thNight
317%42%39%5%
538
16th to endNight
7%213%43%31%2
663
September1st to 15thNight
7%115%38%32%5%
720
16th to endNight
18%110%36%31%2
716
October1st to 15thNight
20%317%32%22%2
720
16th to endNight
32%313%25%20%5%
768
November1st to 15thNight
40%6%14%26%11%
760
16th to endNight
37%6%11%24%17%1
780
December1st to 15thNight
36%413%26%16%2
780
16th to endNight
43%5%14%21%12%
832
Page generated at 2018-02-13 17:45:57. Version ac04

Copyright 2018 A. Danko


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