Payette
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Payette clear sky chart from 2005-11-05 to 2017-10-16.

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
58%
14861
19%
47160
17%
14835
61%
14835
27%
29544

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
42%
716
6%
2506
5%
716
44%
716
10%
2005
January16th to endNight
48%
768
7%
2688
8%
768
49%
768
13%
2072
February1st to 15thNight
48%
698
8%
2270
7%
696
51%
696
16%
1673
February16th to endNight
47%
632
13%
1895
12%
632
50%
632
19%
1373
March1st to 15thNight
47%
720
11%
2160
9%
720
50%
720
19%
1548
March16th to endNight
45%
768
15%
2025
9%
768
48%
768
24%
1427
April1st to 15thNight
52%
719
19%
1799
9%
719
55%
719
30%
1221
April16th to endNight
55%
588
23%
1668
15%
588
59%
588
35%
1004
May1st to 15thNight
59%
503
21%
1583
16%
503
65%
503
39%
857
May16th to endNight
62%
374
19%
1496
26%
374
65%
374
26%
841
June1st to 15thNight
57%
360
15%
1440
19%
360
63%
360
27%
797
June16th to endNight
64%
360
24%
1440
33%
360
73%
360
42%
619
July1st to 15thNight
79%
340
24%
1360
34%
340
85%
340
56%
497
July16th to endNight
76%
376
34%
1416
44%
354
83%
354
59%
501
August1st to 15thNight
79%
450
32%
1522
30%
448
84%
448
56%
646
August16th to endNight
80%
717
37%
1863
25%
717
83%
717
66%
892
September1st to 15thNight
81%
720
36%
1830
23%
720
84%
720
66%
904
September16th to endNight
71%
716
34%
1980
29%
716
74%
716
45%
1105
October1st to 15thNight
65%
720
26%
2042
22%
720
69%
720
40%
1162
October16th to endNight
65%
708
23%
2294
24%
708
67%
708
30%
1372
November1st to 15thNight
58%
700
20%
2275
22%
700
61%
700
24%
1456
November16th to endNight
51%
720
12%
2400
12%
720
53%
720
19%
1635
December1st to 15thNight
49%
720
9%
2520
8%
720
52%
720
14%
1869
December16th to endNight
43%
768
9%
2688
8%
768
46%
768
12%
2068

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
8%5%24424446%49%
48277
Night
11%6%25%42445%6%45%
47333
TransparencyDay
34%6%11%19%17%9%
47948
Night
38%6%11%19%15%8%
47161
SeeingDay
11%414%26%28%15%
5511
Night
13%216%38%25%3
14873

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 15thDay
17%10%49%7%35%5%5%6%22%
1432
16th to endDay
17%13%6%12%7%46%435%18%
1536
February1st to 15thDay
15%10%47%7%45%5%45%29%
1589
16th to endDay
12%8%37%7%36%45%9%32%
1579
March1st to 15thDay
12%9%46%7%36%5%6%7%29%
1800
16th to endDay
13%8%245%35%5%5%7%35%
2195
April1st to 15thDay
8%6%26%5%35%5%6%8%40%
2149
16th to endDay
8%5%34424447%50%
2292
May1st to 15thDay
5%423424349%55%
2366
16th to endDay
7%6%25%5%25%46%8%45%
2615
June1st to 15thDay
8%4344345%5%8%47%
2520
16th to endDay
332213335%69%
2520
July1st to 15thDay
3211212235%71%
2520
16th to endDay
11111224479%
2657
August1st to 15thDay
2212212345%71%
2430
16th to endDay
22231222476%
2336
September1st to 15thDay
221211233474%
2130
16th to endDay
6%313424436%59%
1980
October1st to 15thDay
8%5%14424347%55%
1917
16th to endDay
9%8%36%6%43446%41%
1597
November1st to 15thDay
14%6%35%5%345%6%7%37%
1584
16th to endDay
14%9%28%8%5%5%447%29%
1557
December1st to 15thDay
18%10%5%8%6%35%45%5%24%
1440
16th to endDay
20%11%5%9%8%3433423%
1536
January1st to 15thNight
18%11%410%6%35%45%7%21%
2506
16th to endNight
15%11%5%8%7%34447%27%
2688
February1st to 15thNight
16%10%46%6%345%5%6%31%
2259
16th to endNight
13%9%36%6%345%6%7%31%
1895
March1st to 15thNight
15%8%45%6%35%346%34%
2160
16th to endNight
12%8%36%6%4445%7%35%
2025
April1st to 15thNight
11%5%35%5%35%5%46%44%
1799
16th to endNight
9%5%244145%5%6%50%
1668
May1st to 15thNight
5%3144335%5%7%57%
1583
16th to endNight
6%436%6%25%5%8%9%43%
1496
June1st to 15thNight
8%425%43445%7%50%
1440
16th to endNight
4213322447%63%
1440
July1st to 15thNight
11223348%71%
1440
16th to endNight
11221232477%
1512
August1st to 15thNight
221122236%7%68%
1530
16th to endNight
121211333476%
1863
September1st to 15thNight
221211335%74%
1830
16th to endNight
8%32432333460%
1980
October1st to 15thNight
8%424323446%55%
2042
16th to endNight
9%425%435%5%5%6%47%
2294
November1st to 15thNight
15%5%2442446%6%42%
2275
16th to endNight
17%8%25%5%335%46%37%
2400
December1st to 15thNight
18%9%37%5%35%45%7%30%
2520
16th to endNight
21%11%47%5%35%5%45%25%
2688

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
61%11%16%10%
1432
16th to endDay
69%9%12%8%1
1536
February1st to 15thDay
55%11%16%13%2
1589
16th to endDay
49%8%18%18%4
1579
March1st to 15thDay
51%8%14%18%5%
1800
16th to endDay
47%7%15%21%8%
2195
April1st to 15thDay
40%6%15%24%11%1
2149
16th to endDay
33%5%12%28%17%2
2292
May1st to 15thDay
25%5%10%30%23%4
2366
16th to endDay
34%6%12%25%16%4
2619
June1st to 15thDay
33%6%10%22%21%5%
2520
16th to endDay
18%37%22%32%17%
2520
July1st to 15thDay
15%35%14%28%33%
2371
16th to endDay
8%149%30%45%
2490
August1st to 15thDay
15%26%14%29%30%
2413
16th to endDay
14%25%17%36%25%
2336
September1st to 15thDay
14%35%20%34%21%
2130
16th to endDay
25%48%29%25%5%
1980
October1st to 15thDay
29%5%15%27%20%2
1917
16th to endDay
40%7%15%25%10%
1597
November1st to 15thDay
44%9%18%20%6%
1584
16th to endDay
54%9%16%14%5%
1557
December1st to 15thDay
60%10%15%10%2
1440
16th to endDay
65%6%13%10%3
1536
January1st to 15thNight
62%9%14%11%2
2506
16th to endNight
57%9%16%13%3
2688
February1st to 15thNight
51%9%18%16%4
2270
16th to endNight
50%7%16%18%5%
1895
March1st to 15thNight
51%6%12%21%6%2
2160
16th to endNight
46%6%13%24%8%
2025
April1st to 15thNight
40%6%12%24%15%1
1799
16th to endNight
32%5%10%26%21%3
1668
May1st to 15thNight
25%6%9%22%30%4
1584
16th to endNight
35%6%9%28%14%6%
1496
June1st to 15thNight
33%6%11%22%20%5%
1440
16th to endNight
20%37%18%31%17%
1440
July1st to 15thNight
13%26%17%27%33%
1360
16th to endNight
12%139%24%48%
1416
August1st to 15thNight
14%37%13%26%33%
1522
16th to endNight
13%2414%30%35%
1863
September1st to 15thNight
13%3415%31%31%
1830
16th to endNight
27%25%20%27%15%
1980
October1st to 15thNight
29%49%26%23%5%
2042
16th to endNight
35%5%13%24%19%
2294
November1st to 15thNight
41%6%14%24%11%
2275
16th to endNight
47%7%17%20%7%
2400
December1st to 15thNight
53%9%16%14%6%
2520
16th to endNight
59%7%15%14%2
2688

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
30%1125%23%18%
60
16th to endDay
32%10%17%29%9%
64
February1st to 15thDay
25%29%23%28%11%
182
16th to endDay
18%5%20%29%17%8%
238
March1st to 15thDay
23%6%18%27%18%4
270
16th to endDay
17%12%22%29%15%2
288
April1st to 15thDay
8%14%24%21%17%13%
269
16th to endDay
10%8%24%28%19%8%
270
May1st to 15thDay
7%10%23%25%25%7%
288
16th to endDay
11%315%22%29%17%
330
June1st to 15thDay
9%418%29%25%13%
315
16th to endDay
5%316%26%32%16%
315
July1st to 15thDay
419%22%39%22%
305
16th to endDay
16%34%38%18%
327
August1st to 15thDay
5%16%29%38%19%
315
16th to endDay
36%22%33%33%
332
September1st to 15thDay
5%9%20%31%32%
315
16th to endDay
9%211%21%33%21%
315
October1st to 15thDay
10%314%26%29%14%
315
16th to endDay
18%120%25%26%7%
105
November1st to 15thDay
13%12%24%47%2
90
16th to endDay
26%121%34%12%3
79
December1st to 15thDay
31%15%36%11%5%
60
16th to endDay
29%112%26%18%10%
64
January1st to 15thNight
22%312%34%22%5%
720
16th to endNight
19%211%34%26%5%
768
February1st to 15thNight
22%14%36%22%3
704
16th to endNight
18%220%36%20%1
632
March1st to 15thNight
18%421%34%18%2
720
16th to endNight
16%5%22%39%15%1
768
April1st to 15thNight
11%323%35%23%1
719
16th to endNight
10%425%34%21%2
588
May1st to 15thNight
6%423%39%23%2
504
16th to endNight
7%415%37%30%5%
375
June1st to 15thNight
10%222%36%24%3
360
16th to endNight
5%223%39%28%1
360
July1st to 15thNight
114%51%30%1
340
16th to endNight
2115%51%27%1
376
August1st to 15thNight
314%43%37%2
450
16th to endNight
2111%40%39%5%
717
September1st to 15thNight
319%35%41%7%
720
16th to endNight
9%112%33%35%7%
716
October1st to 15thNight
10%115%41%26%3
720
16th to endNight
12%112%38%29%5%
708
November1st to 15thNight
16%213%38%26%2
700
16th to endNight
21%215%34%21%4
720
December1st to 15thNight
21%213%42%19%1
720
16th to endNight
27%214%37%16%2
768
Page generated at 2017-10-17 14:35:17. Version ac04

Copyright 2017 A. Danko


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