Auburn
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Auburn clear sky chart from 2005-11-05 to 2017-10-06.

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
71%
15294
28%
47090
27%
15260
73%
15260
41%
25117

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
65%
716
19%
2476
21%
716
67%
716
29%
1445
January16th to endNight
60%
768
24%
2496
25%
768
62%
768
28%
1536
February1st to 15thNight
59%
696
23%
2264
24%
696
62%
696
27%
1395
February16th to endNight
57%
632
25%
1895
26%
632
62%
632
30%
1168
March1st to 15thNight
55%
720
17%
2064
17%
720
57%
720
26%
1393
March16th to endNight
56%
768
20%
2053
15%
768
60%
768
30%
1357
April1st to 15thNight
60%
719
19%
1799
12%
719
61%
719
31%
1213
April16th to endNight
67%
720
25%
1800
13%
720
69%
720
46%
1051
May1st to 15thNight
72%
563
29%
1643
22%
563
74%
563
54%
789
May16th to endNight
78%
374
26%
1496
32%
374
80%
374
43%
641
June1st to 15thNight
76%
360
27%
1440
34%
360
80%
360
46%
594
June16th to endNight
89%
360
36%
1440
49%
360
92%
360
65%
479
July1st to 15thNight
96%
340
35%
1360
48%
340
96%
340
75%
417
July16th to endNight
94%
488
40%
1519
42%
457
93%
457
75%
551
August1st to 15thNight
91%
574
38%
1647
30%
571
92%
571
71%
696
August16th to endNight
93%
764
45%
1910
29%
764
94%
764
83%
847
September1st to 15thNight
93%
720
43%
1800
31%
720
93%
720
80%
810
September16th to endNight
86%
716
45%
1941
40%
716
88%
716
69%
888
October1st to 15thNight
75%
684
31%
2052
32%
684
79%
684
52%
996
October16th to endNight
75%
704
35%
2112
37%
704
77%
704
48%
1068
November1st to 15thNight
73%
700
28%
2256
30%
700
75%
700
40%
1194
November16th to endNight
66%
720
24%
2419
26%
720
68%
720
35%
1323
December1st to 15thNight
57%
720
21%
2520
21%
720
61%
720
25%
1528
December16th to endNight
49%
768
21%
2688
21%
768
53%
768
22%
1738

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%31221233464%
48106
Night
12%312212335%60%
47279
TransparencyDay
24%37%19%24%20%
47787
Night
27%38%19%22%18%
47098
SeeingDay
11%5%20%31%24%5%
5934
Night
12%27%33%35%7%
15308

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
19%323333445%46%
1459
16th to endDay
22%6%23313336%43%
1728
February1st to 15thDay
21%414313345%45%
1592
16th to endDay
23%5%24222436%41%
1579
March1st to 15thDay
20%5%245%2425%6%40%
1893
16th to endDay
19%5%24323447%42%
2169
April1st to 15thDay
19%5%23323446%43%
2149
16th to endDay
11%311212335%61%
2160
May1st to 15thDay
5%212212335%69%
2305
16th to endDay
7%212313345%63%
2615
June1st to 15thDay
6%212212335%67%
2520
16th to endDay
211112384%
2520
July1st to 15thDay
1122287%
2520
16th to endDay
1111111285%
2542
August1st to 15thDay
1111287%
2304
16th to endDay
111289%
2292
September1st to 15thDay
111112383%
2160
16th to endDay
31121221478%
2016
October1st to 15thDay
7%11312345%68%
1705
16th to endDay
9%41332323461%
1760
November1st to 15thDay
11%31332345%6%55%
1603
16th to endDay
16%313423336%50%
1539
December1st to 15thDay
21%5%2442332444%
1440
16th to endDay
25%6%23422345%40%
1536
January1st to 15thNight
18%31331335%7%47%
2476
16th to endNight
19%424413435%47%
2496
February1st to 15thNight
20%424424347%43%
2259
16th to endNight
21%414212445%46%
1895
March1st to 15thNight
21%5%14433346%41%
2064
16th to endNight
19%423323346%45%
2053
April1st to 15thNight
14%425%5%235%46%44%
1799
16th to endNight
10%312213346%59%
1800
May1st to 15thNight
6%12213336%68%
1643
16th to endNight
6%212212347%64%
1496
June1st to 15thNight
5%211212326%69%
1440
16th to endNight
1111212382%
1440
July1st to 15thNight
211287%
1440
16th to endNight
11112386%
1624
August1st to 15thNight
11111222381%
1656
16th to endNight
1113385%
1910
September1st to 15thNight
111112385%
1800
16th to endNight
21111223379%
1941
October1st to 15thNight
7%11121223469%
2052
16th to endNight
7%213412337%63%
2112
November1st to 15thNight
11%322213347%57%
2256
16th to endNight
14%312313345%54%
2419
December1st to 15thNight
22%413322335%46%
2520
16th to endNight
25%5%24313335%41%
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
38%311%19%18%8%
1459
16th to endDay
44%37%15%16%13%
1728
February1st to 15thDay
40%210%19%19%6%
1592
16th to endDay
44%311%26%11%3
1579
March1st to 15thDay
45%311%17%15%5%
1893
16th to endDay
42%5%13%18%16%3
2169
April1st to 15thDay
40%411%24%14%4
2149
16th to endDay
25%412%25%26%5%
2160
May1st to 15thDay
18%28%29%30%9%
2305
16th to endDay
23%411%29%23%8%
2619
June1st to 15thDay
19%39%23%22%21%
2520
16th to endDay
7%1315%36%35%
2520
July1st to 15thDay
6%127%27%54%
2371
16th to endDay
8%129%23%55%
2384
August1st to 15thDay
6%1210%29%49%
2288
16th to endDay
41111%37%43%
2292
September1st to 15thDay
7%1212%33%41%
2160
16th to endDay
12%2422%33%24%
2016
October1st to 15thDay
17%36%24%26%20%
1705
16th to endDay
27%28%21%25%15%
1760
November1st to 15thDay
28%412%25%19%8%
1603
16th to endDay
35%49%22%22%5%
1539
December1st to 15thDay
44%39%18%20%3
1440
16th to endDay
45%49%16%17%5%
1536
January1st to 15thNight
37%311%19%17%10%
2476
16th to endNight
40%37%13%18%15%
2496
February1st to 15thNight
41%29%19%18%9%
2271
16th to endNight
38%49%25%18%4
1895
March1st to 15thNight
44%49%19%15%6%
2064
16th to endNight
40%5%9%19%17%6%
2053
April1st to 15thNight
40%5%13%20%14%6%
1799
16th to endNight
26%412%24%23%8%
1800
May1st to 15thNight
18%311%24%28%14%
1644
16th to endNight
19%414%31%20%9%
1496
June1st to 15thNight
17%49%25%23%19%
1440
16th to endNight
9%1314%32%38%
1440
July1st to 15thNight
6%128%27%54%
1360
16th to endNight
7%129%23%56%
1519
August1st to 15thNight
9%2113%26%45%
1647
16th to endNight
6%1111%35%44%
1910
September1st to 15thNight
7%1312%36%39%
1800
16th to endNight
11%2420%33%27%
1941
October1st to 15thNight
20%25%22%26%22%
2052
16th to endNight
22%25%23%26%18%
2112
November1st to 15thNight
27%312%25%19%11%
2256
16th to endNight
31%38%24%21%9%
2419
December1st to 15thNight
41%39%18%18%7%
2520
16th to endNight
47%38%15%17%8%
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
37%5%18%19%17%1
87
16th to endDay
26%5%21%21%19%5%
256
February1st to 15thDay
24%5%20%26%20%2
239
16th to endDay
26%10%19%24%16%1
238
March1st to 15thDay
25%11%21%19%17%4
270
16th to endDay
20%11%26%23%15%2
288
April1st to 15thDay
24%11%27%21%11%3
269
16th to endDay
16%12%26%25%15%3
270
May1st to 15thDay
8%7%30%30%17%5%
288
16th to endDay
9%9%18%26%29%7%
330
June1st to 15thDay
7%6%26%36%20%4
315
16th to endDay
1318%37%29%9%
315
July1st to 15thDay
11%43%37%7%
305
16th to endDay
15%43%30%10%
327
August1st to 15thDay
217%40%31%6%
315
16th to endDay
13%37%34%13%
332
September1st to 15thDay
2113%46%26%8%
315
16th to endDay
3322%34%30%5%
315
October1st to 15thDay
5%8%22%35%23%4
278
16th to endDay
15%418%30%28%2
272
November1st to 15thDay
12%310%22%38%11%
109
16th to endDay
16%223%31%23%2
77
December1st to 15thDay
30%8%21%28%8%3
60
16th to endDay
17%7%12%26%25%10%
64
January1st to 15thNight
19%26%32%29%9%
720
16th to endNight
21%26%34%25%9%
768
February1st to 15thNight
22%37%33%27%5%
704
16th to endNight
22%49%34%23%5%
632
March1st to 15thNight
22%5%8%30%27%6%
720
16th to endNight
20%412%32%25%4
768
April1st to 15thNight
14%5%10%38%27%3
719
16th to endNight
11%410%34%30%8%
720
May1st to 15thNight
8%112%39%32%5%
564
16th to endNight
7%26%35%42%4
375
June1st to 15thNight
6%110%36%41%3
360
16th to endNight
2340%47%4
360
July1st to 15thNight
34%60%2
340
16th to endNight
126%61%8%
488
August1st to 15thNight
2235%52%7%
574
16th to endNight
232%56%7%
764
September1st to 15thNight
1229%56%9%
720
16th to endNight
217%32%41%14%
716
October1st to 15thNight
8%19%35%34%10%
684
16th to endNight
8%18%32%35%12%
704
November1st to 15thNight
12%26%34%32%11%
700
16th to endNight
15%29%36%26%9%
720
December1st to 15thNight
23%28%34%23%7%
720
16th to endNight
28%311%30%21%4
768
Page generated at 2017-10-07 11:07:48. Version ac04

Copyright 2017 A. Danko


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