Nevada City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nevada City clear sky chart from 2005-11-06 to 2024-01-13.

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
62%
23369
28%
74700
24%
23323
68%
23323
38%
40668

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
45%
757
18%
2646
16%
756
51%
756
23%
1670
January11th to 20thNight
51%
728
23%
2436
19%
728
58%
728
25%
1497
January21st to endNight
47%
792
26%
2574
22%
792
56%
792
27%
1587
February1st to 10thNight
48%
720
26%
2340
20%
720
59%
720
29%
1380
February11th to 20thNight
49%
701
26%
2160
21%
700
58%
700
28%
1325
February21st to endNight
47%
592
25%
1776
21%
592
54%
592
28%
1097
March1st to 10thNight
41%
720
15%
2115
11%
720
47%
720
20%
1502
March11th to 20thNight
48%
720
21%
1980
16%
720
54%
720
29%
1297
March21st to endNight
46%
792
18%
2087
10%
792
52%
792
27%
1412
April1st to 10thNight
50%
720
22%
1800
11%
720
54%
720
31%
1211
April11th to 20thNight
54%
711
25%
1779
12%
711
59%
711
38%
1120
April21st to endNight
64%
720
26%
1800
12%
720
68%
720
46%
1045
May1st to 10thNight
57%
638
28%
1718
15%
638
63%
638
45%
945
May11th to 20thNight
70%
354
30%
1416
34%
354
73%
354
41%
625
May21st to endNight
69%
388
26%
1552
30%
388
74%
388
39%
705
June1st to 10thNight
75%
360
26%
1440
32%
360
79%
360
40%
634
June11th to 20thNight
78%
360
35%
1440
42%
360
86%
360
59%
511
June21st to endNight
82%
360
35%
1440
45%
360
88%
360
61%
509
July1st to 10thNight
91%
350
36%
1400
48%
350
94%
350
75%
430
July11th to 20thNight
89%
348
39%
1392
48%
348
92%
348
75%
425
July21st to endNight
85%
540
39%
1626
37%
510
88%
510
69%
649
August1st to 10thNight
84%
537
38%
1602
31%
534
86%
534
66%
692
August11th to 20thNight
90%
670
40%
1738
26%
670
91%
670
80%
763
August21st to endNight
89%
792
43%
1980
26%
792
90%
792
80%
898
September1st to 10thNight
88%
720
46%
1800
30%
720
90%
720
81%
805
September11th to 20thNight
81%
720
44%
1800
33%
720
85%
720
70%
870
September21st to endNight
73%
720
43%
2009
34%
720
81%
720
68%
905
October1st to 10thNight
72%
720
32%
2160
31%
720
78%
720
52%
1027
October11th to 20thNight
72%
720
39%
2160
39%
720
78%
720
53%
1021
October21st to endNight
67%
792
38%
2376
35%
792
76%
792
51%
1161
November1st to 10thNight
59%
740
28%
2386
27%
740
65%
740
35%
1328
November11th to 20thNight
60%
760
28%
2470
24%
760
68%
760
37%
1327
November21st to endNight
53%
760
27%
2607
24%
760
61%
760
32%
1432
December1st to 10thNight
49%
760
24%
2660
20%
760
59%
760
27%
1531
December11th to 20thNight
44%
760
20%
3223
19%
759
52%
759
16%
2242
December21st to endNight
40%
827
14%
4812
16%
817
50%
817
11%
3090

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
11%413323345%61%
74743
Night
13%423323345%58%
74996
TransparencyDay
26%37%18%24%21%
74455
Night
30%37%18%22%20%
74805
SeeingDay
14%9%26%33%14%5%
13978
Night
15%414%34%28%6%
23385

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
24%8%35%423347%37%
1519
11th to 20thDay
18%6%14324436%49%
1564
21st to endDay
20%8%2432345%7%42%
1782
February1st to 10thDay
21%6%23323446%47%
1620
11th to 20thDay
18%8%233235%36%47%
1686
21st to endDay
22%9%1342343444%
1480
March1st to 10thDay
21%11%35%5%3345%7%34%
1843
11th to 20thDay
23%7%2442335%6%40%
1980
21st to endDay
22%7%2433435%6%40%
2268
April1st to 10thDay
19%7%3442345%7%43%
2160
11th to 20thDay
16%5%243235%46%51%
2129
21st to endDay
11%423323447%57%
2160
May1st to 10thDay
9%5%2332335%6%61%
2238
11th to 20thDay
7%32342335%7%61%
2477
21st to endDay
9%42342445%6%58%
2723
June1st to 10thDay
8%32332335%7%61%
2520
11th to 20thDay
3212212235%78%
2520
21st to endDay
32121122383%
2520
July1st to 10thDay
11111222388%
2520
11th to 20thDay
11111112486%
2520
21st to endDay
111221223482%
2592
August1st to 10thDay
221211222382%
2328
11th to 20thDay
111111222485%
2161
21st to endDay
1111111291%
2376
September1st to 10thDay
21111122387%
2160
11th to 20thDay
4212222335%75%
2160
21st to endDay
5%212112235%77%
1945
October1st to 10thDay
6%31332243469%
1800
11th to 20thDay
7%312213346%68%
1800
21st to endDay
9%31332344463%
1980
November1st to 10thDay
14%6%23324346%51%
1692
11th to 20thDay
16%31342445%6%50%
1710
21st to endDay
13%5%2442435%6%52%
1568
December1st to 10thDay
19%5%2432345%7%46%
1520
11th to 20thDay
30%8%35%423345%32%
1928
21st to endDay
17%8%25%6%35%5%6%8%37%
2794
January1st to 10thNight
23%6%3432345%7%40%
2646
11th to 20thNight
17%6%24423447%46%
2436
21st to endNight
20%6%24423346%45%
2574
February1st to 10thNight
20%5%13323346%50%
2340
11th to 20thNight
17%7%24434446%47%
2160
21st to endNight
20%9%23323445%45%
1776
March1st to 10thNight
25%10%2442434436%
2115
11th to 20thNight
21%6%2343445%7%41%
1980
21st to endNight
21%6%2433345%444%
2087
April1st to 10thNight
17%7%35%424346%46%
1800
11th to 20thNight
15%433324447%52%
1779
21st to endNight
11%323223347%60%
1800
May1st to 10thNight
9%423323446%61%
1718
11th to 20thNight
8%32233435%7%60%
1416
21st to endNight
8%424323446%61%
1552
June1st to 10thNight
8%312323336%66%
1440
11th to 20thNight
2212222336%76%
1440
21st to endNight
311231321381%
1440
July1st to 10thNight
1121222387%
1440
11th to 20thNight
11211211289%
1440
21st to endNight
121221223480%
1722
August1st to 10thNight
331222232377%
1611
11th to 20thNight
111111223483%
1738
21st to endNight
11121222386%
1980
September1st to 10thNight
11111112486%
1800
11th to 20thNight
3312212235%77%
1800
21st to endNight
322212345%76%
2009
October1st to 10thNight
7%31222322472%
2160
11th to 20thNight
7%312212235%71%
2160
21st to endNight
10%212212346%67%
2376
November1st to 10thNight
16%6%23312346%54%
2386
11th to 20thNight
12%42432345%7%55%
2470
21st to endNight
13%5%245%23346%54%
2607
December1st to 10thNight
22%5%12323346%49%
2660
11th to 20thNight
33%7%2332335%7%32%
3276
21st to endNight
21%7%36%6%35%45%6%34%
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
48%48%21%14%5%
1519
11th to 20thDay
38%48%17%18%15%
1564
21st to endDay
43%28%15%21%10%
1782
February1st to 10thDay
41%28%19%19%11%
1620
11th to 20thDay
39%39%18%24%7%
1695
21st to endDay
43%39%21%16%7%
1480
March1st to 10thDay
50%410%16%16%5%
1843
11th to 20thDay
46%39%21%16%5%
1980
21st to endDay
44%5%13%20%15%4
2268
April1st to 10thDay
40%5%11%23%17%4
2160
11th to 20thDay
33%413%24%20%7%
2132
21st to endDay
27%313%28%25%4
2160
May1st to 10thDay
24%310%28%28%8%
2238
11th to 20thDay
22%410%31%24%10%
2480
21st to endDay
25%414%30%22%6%
2724
June1st to 10thDay
22%311%25%27%13%
2520
11th to 20thDay
11%29%20%34%24%
2520
21st to endDay
9%1314%38%35%
2520
July1st to 10thDay
6%1210%26%55%
2451
11th to 20thDay
6%1312%25%53%
2445
21st to endDay
10%227%25%55%
2448
August1st to 10thDay
9%1311%30%46%
2312
11th to 20thDay
6%2110%35%47%
2161
21st to endDay
5%1111%36%46%
2376
September1st to 10thDay
6%128%27%56%
2160
11th to 20thDay
14%15%20%35%25%
2160
21st to endDay
13%2418%34%29%
1945
October1st to 10thDay
19%35%20%28%26%
1800
11th to 20thDay
19%36%18%27%27%
1800
21st to endDay
25%35%18%25%24%
1980
November1st to 10thDay
34%37%20%22%14%
1692
11th to 20thDay
34%410%19%23%10%
1710
21st to endDay
33%49%18%24%13%
1568
December1st to 10thDay
38%47%21%19%11%
1520
11th to 20thDay
57%26%14%14%6%
1928
21st to endDay
46%414%20%13%4
2794
January1st to 10thNight
44%411%21%14%7%
2646
11th to 20thNight
39%6%9%13%18%16%
2436
21st to endNight
41%38%15%21%12%
2574
February1st to 10thNight
38%36%19%20%14%
2340
11th to 20thNight
38%5%7%19%22%9%
2162
21st to endNight
39%48%24%18%7%
1776
March1st to 10thNight
51%5%8%16%14%5%
2115
11th to 20thNight
42%39%20%18%7%
1980
21st to endNight
42%6%9%22%15%6%
2087
April1st to 10thNight
41%5%12%18%19%6%
1800
11th to 20thNight
33%5%12%23%19%9%
1779
21st to endNight
25%5%12%31%22%6%
1800
May1st to 10thNight
25%410%21%29%11%
1718
11th to 20thNight
22%313%30%21%11%
1416
21st to endNight
23%414%29%23%6%
1552
June1st to 10thNight
21%5%11%25%26%12%
1440
11th to 20thNight
12%28%21%32%25%
1440
21st to endNight
12%2313%33%38%
1440
July1st to 10thNight
6%1211%28%51%
1400
11th to 20thNight
7%1212%21%58%
1392
21st to endNight
11%227%21%58%
1626
August1st to 10thNight
13%1214%24%46%
1602
11th to 20thNight
7%1212%30%48%
1738
21st to endNight
7%1210%27%52%
1980
September1st to 10thNight
7%127%29%54%
1800
11th to 20thNight
12%26%16%40%24%
1800
21st to endNight
12%2419%32%32%
2009
October1st to 10thNight
19%36%18%26%29%
2160
11th to 20thNight
18%2419%27%30%
2160
21st to endNight
21%25%20%27%25%
2376
November1st to 10thNight
33%39%20%18%17%
2386
11th to 20thNight
29%410%21%25%11%
2470
21st to endNight
32%47%19%22%16%
2607
December1st to 10thNight
37%38%19%18%15%
2660
11th to 20thNight
54%36%14%17%7%
3276
21st to endNight
51%411%17%12%5%
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
42%5%24%17%9%2
180
11th to 20thDay
26%7%24%28%12%3
272
21st to endDay
26%8%24%23%15%4
374
February1st to 10thDay
28%10%23%25%11%3
340
11th to 20thDay
25%14%29%23%9%1
386
21st to endDay
24%16%29%23%8%1
346
March1st to 10thDay
35%16%22%19%5%2
420
11th to 20thDay
31%13%26%17%10%2
420
21st to endDay
25%18%29%22%6%
462
April1st to 10thDay
24%16%33%19%7%2
420
11th to 20thDay
24%18%28%23%6%1
412
21st to endDay
13%16%27%28%13%3
420
May1st to 10thDay
14%18%29%26%11%3
423
11th to 20thDay
13%12%29%27%13%5%
448
21st to endDay
11%10%27%32%14%7%
485
June1st to 10thDay
7%11%27%36%12%7%
450
11th to 20thDay
6%13%30%37%10%6%
450
21st to endDay
26%27%43%14%8%
450
July1st to 10thDay
1326%50%13%7%
446
11th to 20thDay
1124%48%18%8%
444
21st to endDay
1222%51%19%5%
487
August1st to 10thDay
2423%45%20%6%
447
11th to 20thDay
1225%45%20%6%
437
21st to endDay
1221%50%21%4
495
September1st to 10thDay
3326%44%19%5%
450
11th to 20thDay
9%6%27%35%20%3
450
21st to endDay
6%8%29%37%15%4
450
October1st to 10thDay
5%12%28%31%17%6%
450
11th to 20thDay
8%8%24%37%16%7%
450
21st to endDay
13%9%23%31%19%5%
495
November1st to 10thDay
19%6%20%25%23%6%
288
11th to 20thDay
15%420%31%23%7%
270
21st to endDay
14%8%19%32%22%5%
203
December1st to 10thDay
28%6%20%23%14%9%
180
11th to 20thDay
23%6%28%20%15%8%
180
21st to endDay
25%8%24%24%16%3
198
January1st to 10thNight
27%417%28%20%4
760
11th to 20thNight
22%417%40%15%2
728
21st to endNight
23%418%29%23%4
792
February1st to 10thNight
23%318%34%19%2
720
11th to 20thNight
21%5%17%34%19%4
704
21st to endNight
26%7%15%37%13%2
592
March1st to 10thNight
30%6%15%29%17%3
720
11th to 20thNight
24%5%15%29%23%3
720
21st to endNight
24%6%18%32%18%2
792
April1st to 10thNight
21%417%36%20%2
720
11th to 20thNight
18%6%17%33%22%5%
711
21st to endNight
12%5%15%37%25%6%
720
May1st to 10thNight
11%5%21%33%26%4
638
11th to 20thNight
10%313%34%35%5%
354
21st to endNight
10%310%33%39%5%
389
June1st to 10thNight
8%311%35%38%6%
360
11th to 20thNight
2312%40%36%7%
360
21st to endNight
319%39%42%7%
360
July1st to 10thNight
15%35%53%7%
350
11th to 20thNight
16%39%46%8%
348
21st to endNight
217%28%50%12%
540
August1st to 10thNight
416%32%46%10%
537
11th to 20thNight
116%41%40%11%
670
21st to endNight
16%36%50%6%
792
September1st to 10thNight
217%40%44%7%
720
11th to 20thNight
429%35%39%11%
720
21st to endNight
4218%34%32%10%
720
October1st to 10thNight
8%312%42%29%6%
720
11th to 20thNight
9%412%36%33%7%
720
21st to endNight
11%414%33%28%10%
792
November1st to 10thNight
18%412%30%28%7%
740
11th to 20thNight
13%316%39%23%5%
760
21st to endNight
15%6%18%36%20%5%
760
December1st to 10thNight
25%5%16%30%19%5%
760
11th to 20thNight
31%414%30%17%3
760
21st to endNight
27%5%18%33%15%2
836
Page generated at 2024-01-09 22:25:06. Version ac07

Copyright 2024 Attilla Danko


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