Yerington
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Yerington clear sky chart from 2005-11-05 to 2018-01-20.

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
70%
15692
29%
48477
27%
15667
74%
15667
47%
24192

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
68%
776
22%
2716
22%
776
73%
776
36%
1422
January16th to endNight
68%
788
23%
2624
25%
788
71%
788
34%
1434
February1st to 15thNight
66%
696
24%
2193
25%
696
69%
696
39%
1192
February16th to endNight
60%
632
26%
1895
25%
632
66%
632
39%
1052
March1st to 15thNight
60%
720
24%
2154
21%
720
67%
720
43%
1127
March16th to endNight
56%
768
24%
1995
16%
768
62%
768
44%
1142
April1st to 15thNight
56%
719
25%
1799
12%
719
61%
719
41%
1068
April16th to endNight
58%
720
26%
1800
14%
720
61%
720
44%
1048
May1st to 15thNight
60%
560
30%
1640
23%
560
63%
560
50%
810
May16th to endNight
64%
386
25%
1508
27%
386
68%
386
36%
721
June1st to 15thNight
72%
360
28%
1440
36%
360
78%
360
46%
606
June16th to endNight
82%
360
34%
1440
43%
360
88%
360
67%
475
July1st to 15thNight
88%
340
31%
1360
41%
340
90%
340
61%
485
July16th to endNight
84%
379
37%
1419
44%
357
87%
357
52%
549
August1st to 15thNight
80%
648
35%
1722
25%
645
82%
645
66%
814
August16th to endNight
82%
764
42%
1910
26%
764
83%
764
77%
874
September1st to 15thNight
83%
720
39%
1800
27%
720
85%
720
71%
850
September16th to endNight
79%
716
43%
1962
37%
716
83%
716
66%
906
October1st to 15thNight
76%
720
33%
2098
31%
720
82%
720
55%
1015
October16th to endNight
77%
768
40%
2361
41%
768
82%
768
58%
1070
November1st to 15thNight
76%
760
30%
2470
31%
760
80%
760
49%
1170
November16th to endNight
70%
780
32%
2535
31%
780
75%
780
46%
1245
December1st to 15thNight
66%
780
20%
2724
20%
780
70%
780
34%
1465
December16th to endNight
59%
832
24%
2912
24%
832
64%
832
30%
1652

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
3313323346%63%
49069
Night
3313323346%63%
48651
TransparencyDay
21%49%20%23%19%
48741
Night
21%411%24%23%15%
48478
SeeingDay
6%13%27%29%16%6%
6090
Night
4316%40%28%6%
15706

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
3425%4345%6%10%50%
1552
16th to endDay
35%25%5%245%7%9%46%
1701
February1st to 15thDay
25%343245%5%11%51%
1669
16th to endDay
1325%33435%10%56%
1579
March1st to 15thDay
14133245%6%11%54%
1803
16th to endDay
23243345%6%9%55%
2229
April1st to 15thDay
45%2442445%8%52%
2149
16th to endDay
4313213346%64%
2160
May1st to 15thDay
4312312347%65%
2310
16th to endDay
6%414423445%57%
2602
June1st to 15thDay
3313223345%65%
2520
16th to endDay
1121223478%
2520
July1st to 15thDay
2112224345%68%
2520
16th to endDay
121232334469%
2651
August1st to 15thDay
11221334472%
2227
16th to endDay
1121222478%
2292
September1st to 15thDay
21211222477%
2160
16th to endDay
11121223477%
1998
October1st to 15thDay
3212322245%70%
1860
16th to endDay
2212222346%70%
1863
November1st to 15thDay
3312213347%63%
1719
16th to endDay
122232435%8%62%
1755
December1st to 15thDay
2324427%46%9%51%
1566
16th to endDay
46%35%5%35%6%6%8%42%
1664
January1st to 15thNight
36%3432435%8%55%
2716
16th to endNight
35%25%425%5%5%7%52%
2624
February1st to 15thNight
25%2332447%8%53%
2182
16th to endNight
25%2432445%7%57%
1895
March1st to 15thNight
341331346%7%58%
2154
16th to endNight
242342445%8%57%
1995
April1st to 15thNight
44234346%48%55%
1799
16th to endNight
5%413313347%61%
1800
May1st to 15thNight
5%312212336%66%
1640
16th to endNight
7%414323446%58%
1508
June1st to 15thNight
4312222236%68%
1440
16th to endNight
1111222382%
1440
July1st to 15thNight
11213345%74%
1440
16th to endNight
1112223235%71%
1515
August1st to 15thNight
11221224375%
1731
16th to endNight
1112235%79%
1910
September1st to 15thNight
11221122479%
1800
16th to endNight
3111111235%76%
1962
October1st to 15thNight
321222333470%
2098
16th to endNight
321212235%72%
2361
November1st to 15thNight
221221235%6%67%
2470
16th to endNight
2323323348%62%
2535
December1st to 15thNight
441442445%9%54%
2724
16th to endNight
46%35%43447%9%47%
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
27%7%20%30%13%
1552
16th to endDay
32%8%16%24%16%2
1701
February1st to 15thDay
27%6%15%26%19%4
1669
16th to endDay
25%5%14%33%18%3
1579
March1st to 15thDay
23%6%15%27%20%5%
1803
16th to endDay
24%5%19%27%17%5%
2229
April1st to 15thDay
30%5%11%23%21%7%
2149
16th to endDay
22%411%27%25%9%
2160
May1st to 15thDay
20%38%24%31%10%
2310
16th to endDay
28%6%7%20%25%10%
2606
June1st to 15thDay
21%47%16%27%22%
2520
16th to endDay
10%239%27%45%
2520
July1st to 15thDay
17%249%17%48%
2371
16th to endDay
17%349%17%47%
2484
August1st to 15thDay
14%349%18%48%
2211
16th to endDay
11%228%26%48%
2292
September1st to 15thDay
13%2410%26%43%
2160
16th to endDay
12%2319%34%27%
1998
October1st to 15thDay
17%26%22%34%17%
1860
16th to endDay
15%28%27%33%12%
1863
November1st to 15thDay
21%415%27%25%5%
1719
16th to endDay
20%416%30%24%3
1755
December1st to 15thDay
27%8%16%29%17%1
1566
16th to endDay
36%8%16%24%12%1
1664
January1st to 15thNight
27%5%17%31%16%1
2716
16th to endNight
28%6%17%24%19%3
2624
February1st to 15thNight
26%5%15%31%14%5%
2193
16th to endNight
24%7%15%33%16%3
1895
March1st to 15thNight
23%415%27%20%7%
2154
16th to endNight
24%5%17%27%19%5%
1995
April1st to 15thNight
27%5%14%28%20%4
1799
16th to endNight
25%5%11%27%24%7%
1800
May1st to 15thNight
20%38%24%32%10%
1641
16th to endNight
26%311%22%26%9%
1508
June1st to 15thNight
19%36%19%27%23%
1440
16th to endNight
8%1313%30%41%
1440
July1st to 15thNight
10%249%23%48%
1360
16th to endNight
16%2410%18%48%
1419
August1st to 15thNight
13%2414%20%45%
1722
16th to endNight
8%1411%30%43%
1910
September1st to 15thNight
10%25%11%28%42%
1800
16th to endNight
13%15%16%33%29%
1962
October1st to 15thNight
17%36%23%33%15%
2098
16th to endNight
15%36%27%34%12%
2361
November1st to 15thNight
18%5%12%33%22%7%
2470
16th to endNight
21%411%32%26%4
2535
December1st to 15thNight
27%7%17%27%18%1
2724
16th to endNight
32%6%16%29%13%1
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
8%7%22%36%16%7%
90
16th to endDay
7%7%22%33%23%4
204
February1st to 15thDay
5%13%20%34%20%5%
253
16th to endDay
7%17%26%33%13%1
238
March1st to 15thDay
10%19%24%28%14%4
270
16th to endDay
9%26%22%29%11%
288
April1st to 15thDay
12%21%28%22%10%4
269
16th to endDay
11%24%29%24%8%2
270
May1st to 15thDay
12%20%30%19%12%4
288
16th to endDay
14%14%21%27%13%7%
330
June1st to 15thDay
7%20%32%22%12%4
315
16th to endDay
411%33%26%17%6%
315
July1st to 15thDay
49%29%28%19%7%
305
16th to endDay
37%33%32%15%7%
327
August1st to 15thDay
311%34%28%13%8%
315
16th to endDay
27%33%27%17%11%
332
September1st to 15thDay
47%28%33%18%8%
315
16th to endDay
310%23%37%18%6%
315
October1st to 15thDay
5%10%28%29%19%6%
315
16th to endDay
5%9%20%32%25%7%
279
November1st to 15thDay
5%217%31%28%14%
135
16th to endDay
28%21%33%29%5%
135
December1st to 15thDay
18%27%31%19%10%
91
16th to endDay
10%7%10%30%32%9%
96
January1st to 15thNight
5%214%40%26%10%
780
16th to endNight
4214%44%23%9%
788
February1st to 15thNight
4219%40%26%5%
704
16th to endNight
4424%39%21%4
632
March1st to 15thNight
5%5%22%38%22%5%
720
16th to endNight
46%28%37%20%3
768
April1st to 15thNight
5%8%24%36%22%2
719
16th to endNight
7%7%22%34%21%6%
720
May1st to 15thNight
7%6%23%37%22%2
561
16th to endNight
9%218%37%29%2
387
June1st to 15thNight
6%116%46%27%1
360
16th to endNight
111%55%28%2
360
July1st to 15thNight
25%52%37%1
340
16th to endNight
27%51%37%1
379
August1st to 15thNight
211%42%38%3
648
16th to endNight
111%39%40%5%
764
September1st to 15thNight
219%35%43%8%
720
16th to endNight
4211%32%40%8%
716
October1st to 15thNight
4113%39%29%11%
720
16th to endNight
4111%34%33%14%
768
November1st to 15thNight
4113%43%27%10%
760
16th to endNight
4315%42%25%7%
780
December1st to 15thNight
6%117%41%23%8%
780
16th to endNight
7%321%42%20%3
832
Page generated at 2018-01-21 09:19:20. Version ac04

Copyright 2018 A. Danko


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