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 2018-03-11.

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
37%
16613
16%
49024
11%
16570
43%
16570
21%
33840

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
16%
975
11%
2716
4%
970
23%
970
13%
2129
January16th to endNight
20%
975
10%
2847
4%
975
26%
975
13%
2228
February1st to 15thNight
19%
762
10%
2370
3%
761
25%
761
13%
1786
February16th to endNight
21%
683
14%
2049
5%
683
29%
683
13%
1539
March1st to 15thNight
28%
764
13%
2250
9%
764
31%
764
18%
1613
March16th to endNight
32%
759
18%
2103
9%
759
39%
759
21%
1480
April1st to 15thNight
31%
539
15%
1797
10%
539
38%
539
19%
1238
April16th to endNight
36%
540
21%
1641
10%
540
46%
540
24%
1090
May1st to 15thNight
34%
540
13%
1620
7%
540
40%
540
19%
1176
May16th to endNight
47%
562
16%
1643
11%
561
52%
561
30%
1037
June1st to 15thNight
54%
540
16%
1440
12%
540
58%
540
35%
895
June16th to endNight
55%
540
17%
1440
11%
540
60%
540
34%
921
July1st to 15thNight
64%
510
17%
1360
14%
510
66%
510
38%
827
July16th to endNight
69%
564
21%
1469
17%
531
72%
531
41%
840
August1st to 15thNight
68%
539
21%
1609
17%
536
70%
536
38%
915
August16th to endNight
69%
573
20%
1827
19%
573
72%
573
33%
1069
September1st to 15thNight
61%
631
26%
1891
23%
631
65%
631
34%
1109
September16th to endNight
61%
717
27%
1980
21%
717
65%
717
36%
1188
October1st to 15thNight
49%
720
23%
2016
18%
720
54%
720
31%
1266
October16th to endNight
30%
768
19%
2451
13%
768
38%
768
19%
1659
November1st to 15thNight
36%
760
22%
2471
16%
760
45%
760
24%
1561
November16th to endNight
27%
780
15%
2535
10%
780
34%
780
15%
1851
December1st to 15thNight
21%
832
8%
2587
4%
832
25%
832
11%
2017
December16th to endNight
16%
1040
8%
2912
3%
1040
21%
1040
10%
2406

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
14%8%36%6%35%45%7%33%
49596
Night
15%8%36%5%34446%36%
49198
Cloud CoverDay
14%8%36%6%35%45%7%33%
49605
Night
15%8%36%5%34446%36%
49203
TransparencyDay
48%6%12%19%11%1
49288
Night
47%5%11%20%12%1
49024
SeeingDay
17%7%25%24%16%7%
6429
Night
19%8%28%29%13%1
16616

By Month

Percentage Cloud Cover NE (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%16%5%9%6%33435%20%
1552
16th to endDay
14%17%8%10%7%35%435%18%
1726
February1st to 15thDay
16%13%6%10%7%45%346%20%
1820
16th to endDay
16%13%6%9%7%4445%6%21%
1710
March1st to 15thDay
18%11%48%6%35%446%25%
1937
16th to endDay
19%8%37%6%35%45%7%28%
2130
April1st to 15thDay
19%9%36%5%25%45%6%31%
2151
16th to endDay
16%7%26%5%2445%7%36%
2317
May1st to 15thDay
19%8%37%6%3445%7%29%
2331
16th to endDay
11%5%25%6%35%5%6%8%39%
2469
June1st to 15thDay
10%5%25%5%35%5%5%8%41%
2520
16th to endDay
10%5%25%6%36%6%6%9%37%
2520
July1st to 15thDay
7%425%6%345%6%9%42%
2520
16th to endDay
6%435%5%35%6%7%9%41%
2598
August1st to 15thDay
6%425%5%35%6%6%10%42%
2340
16th to endDay
10%6%245%45%5%7%8%40%
2372
September1st to 15thDay
12%5%25%5%35%45%7%43%
2055
16th to endDay
12%5%135%3445%7%44%
1980
October1st to 15thDay
14%6%26%6%25%45%6%39%
1942
16th to endDay
20%7%25%5%445%5%5%31%
1770
November1st to 15thDay
15%7%25%424447%41%
1717
16th to endDay
19%12%48%5%24346%27%
1755
December1st to 15thDay
17%15%7%10%7%3434421%
1700
16th to endDay
21%15%7%9%6%24446%16%
1664
January1st to 15thNight
21%11%48%7%34336%24%
2716
16th to endNight
15%13%6%8%7%45%445%23%
2847
February1st to 15thNight
17%12%5%8%6%24345%28%
2368
16th to endNight
18%10%5%8%5%45%445%28%
2049
March1st to 15thNight
16%8%47%5%44345%33%
2237
16th to endNight
14%8%37%5%3446%6%35%
2103
April1st to 15thNight
18%6%35%435%5%6%7%34%
1797
16th to endNight
16%6%26%5%235%46%40%
1641
May1st to 15thNight
20%7%35%5%45%5%5%6%31%
1620
16th to endNight
13%5%244235%5%7%44%
1641
June1st to 15thNight
9%4245%235%5%8%48%
1440
16th to endNight
6%3246%35%5%6%9%44%
1440
July1st to 15thNight
6%325%3245%5%9%50%
1440
16th to endNight
6%31441346%9%52%
1569
August1st to 15thNight
44244345%5%10%50%
1620
16th to endNight
9%4144245%5%8%49%
1827
September1st to 15thNight
11%323434336%53%
1891
16th to endNight
12%414324445%52%
1980
October1st to 15thNight
13%5%2442335%7%46%
2016
16th to endNight
20%7%25%434345%37%
2451
November1st to 15thNight
15%7%3443335%6%41%
2471
16th to endNight
20%10%47%5%3345%6%27%
2535
December1st to 15thNight
19%13%6%8%5%35%345%23%
2587
16th to endNight
23%14%5%9%6%24445%18%
2912

Percentage Cloud Cover SE (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%16%5%9%6%44445%19%
1552
16th to endDay
14%17%8%11%7%35%435%18%
1726
February1st to 15thDay
15%13%6%10%7%45%346%20%
1820
16th to endDay
16%13%6%10%7%44446%20%
1710
March1st to 15thDay
18%10%5%8%6%26%446%25%
1947
16th to endDay
19%8%37%7%35%447%27%
2129
April1st to 15thDay
19%9%36%5%25%45%6%31%
2151
16th to endDay
16%7%36%5%3345%7%36%
2317
May1st to 15thDay
19%8%37%6%445%5%6%29%
2331
16th to endDay
11%5%25%6%35%5%6%8%39%
2469
June1st to 15thDay
10%435%5%35%5%6%8%41%
2520
16th to endDay
10%425%6%45%6%6%8%37%
2520
July1st to 15thDay
7%425%5%345%6%9%42%
2520
16th to endDay
6%435%5%45%7%7%9%41%
2598
August1st to 15thDay
6%425%5%35%6%6%10%42%
2340
16th to endDay
10%6%25%5%445%6%8%40%
2372
September1st to 15thDay
12%5%25%5%3445%7%42%
2055
16th to endDay
12%5%135%25%45%7%44%
1980
October1st to 15thDay
14%6%26%5%35%45%6%39%
1942
16th to endDay
20%7%25%5%445%5%6%31%
1770
November1st to 15thDay
15%7%34424347%41%
1717
16th to endDay
19%13%48%6%24346%26%
1755
December1st to 15thDay
17%15%7%10%6%35%34421%
1700
16th to endDay
21%15%7%10%5%34446%16%
1664
January1st to 15thNight
21%11%48%7%34346%24%
2716
16th to endNight
15%13%6%8%7%45%446%23%
2847
February1st to 15thNight
16%12%5%8%6%24336%27%
2361
16th to endNight
18%10%6%7%6%35%435%28%
2049
March1st to 15thNight
16%8%47%6%44345%33%
2250
16th to endNight
14%8%37%5%2446%6%35%
2103
April1st to 15thNight
18%6%35%335%5%6%7%33%
1797
16th to endNight
15%6%26%5%235%46%40%
1641
May1st to 15thNight
19%7%35%5%45%5%5%6%31%
1619
16th to endNight
13%5%2442445%7%44%
1641
June1st to 15thNight
9%5%235%235%5%7%48%
1440
16th to endNight
6%3246%35%5%6%9%44%
1440
July1st to 15thNight
6%315%4245%6%10%50%
1440
16th to endNight
5%31441346%9%52%
1569
August1st to 15thNight
4414435%45%10%50%
1620
16th to endNight
9%3145%2446%7%49%
1827
September1st to 15thNight
11%313434336%53%
1891
16th to endNight
12%5%14323445%52%
1980
October1st to 15thNight
14%5%2442345%7%46%
2016
16th to endNight
19%8%25%424345%37%
2451
November1st to 15thNight
15%7%35%42335%6%41%
2471
16th to endNight
20%10%47%5%34446%27%
2535
December1st to 15thNight
19%13%6%8%5%35%345%23%
2587
16th to endNight
22%14%5%9%6%34445%18%
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
66%5%12%11%5%
1553
16th to endDay
67%5%11%10%4
1726
February1st to 15thDay
65%49%13%6%
1822
16th to endDay
63%5%11%14%4
1710
March1st to 15thDay
58%5%11%16%7%
1947
16th to endDay
55%5%12%19%5%1
2130
April1st to 15thDay
53%5%10%19%11%
2151
16th to endDay
45%6%12%18%12%4
2317
May1st to 15thDay
53%6%11%19%8%
2331
16th to endDay
41%8%11%22%13%2
2473
June1st to 15thDay
39%6%10%24%16%1
2520
16th to endDay
40%7%13%20%16%1
2520
July1st to 15thDay
36%7%12%21%19%2
2371
16th to endDay
34%8%16%23%14%2
2435
August1st to 15thDay
34%9%13%24%16%2
2327
16th to endDay
38%7%12%21%15%3
2372
September1st to 15thDay
39%5%12%22%18%2
2055
16th to endDay
36%5%10%26%20%1
1980
October1st to 15thDay
44%412%22%14%1
1942
16th to endDay
51%5%14%18%8%
1770
November1st to 15thDay
42%411%23%16%1
1717
16th to endDay
58%5%10%18%6%
1755
December1st to 15thDay
65%410%13%5%
1700
16th to endDay
68%5%12%9%3
1664
January1st to 15thNight
61%411%14%8%
2716
16th to endNight
62%413%15%3
2847
February1st to 15thNight
58%5%12%16%6%1
2370
16th to endNight
58%49%19%7%
2049
March1st to 15thNight
52%411%19%10%1
2250
16th to endNight
47%6%10%23%9%2
2103
April1st to 15thNight
47%7%10%19%14%
1797
16th to endNight
43%6%9%19%17%3
1641
May1st to 15thNight
51%6%11%18%9%2
1620
16th to endNight
38%5%14%23%14%3
1643
June1st to 15thNight
33%6%12%26%19%1
1440
16th to endNight
34%7%17%22%15%2
1440
July1st to 15thNight
29%7%13%24%21%3
1360
16th to endNight
25%8%16%26%19%4
1469
August1st to 15thNight
28%6%14%26%21%2
1609
16th to endNight
31%7%12%23%20%4
1827
September1st to 15thNight
32%5%10%25%21%4
1891
16th to endNight
32%5%9%28%21%2
1980
October1st to 15thNight
36%5%10%26%19%
2016
16th to endNight
48%411%24%10%1
2451
November1st to 15thNight
42%410%24%15%2
2471
16th to endNight
56%412%18%7%
2535
December1st to 15thNight
62%410%13%7%
2587
16th to endNight
67%5%10%11%4
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
27%8%38%17%7%
135
16th to endDay
29%12%38%15%3
144
February1st to 15thDay
25%18%39%14%2
135
16th to endDay
26%17%35%15%5%
120
March1st to 15thDay
29%17%24%22%6%
163
16th to endDay
25%8%33%23%6%1
288
April1st to 15thDay
25%10%31%21%9%1
270
16th to endDay
20%9%31%17%14%7%
270
May1st to 15thDay
24%7%25%25%11%5%
288
16th to endDay
18%7%26%24%13%10%
369
June1st to 15thDay
13%5%28%30%15%6%
495
16th to endDay
12%6%30%27%16%5%
495
July1st to 15thDay
11%324%31%18%10%
475
16th to endDay
7%119%31%26%13%
458
August1st to 15thDay
8%14%29%27%20%
313
16th to endDay
13%215%21%28%18%
332
September1st to 15thDay
13%413%24%30%13%
315
16th to endDay
14%411%22%32%14%
314
October1st to 15thDay
17%5%22%30%17%6%
315
16th to endDay
23%12%28%29%6%
186
November1st to 15thDay
17%8%28%25%15%4
135
16th to endDay
22%14%38%17%7%
135
December1st to 15thDay
22%20%34%15%8%
135
16th to endDay
25%24%36%12%1
144
January1st to 15thNight
26%12%35%20%5%
975
16th to endNight
20%12%37%24%4
975
February1st to 15thNight
24%11%38%22%3
764
16th to endNight
23%13%33%25%4
683
March1st to 15thNight
22%10%32%27%7%
764
16th to endNight
17%10%34%28%9%
759
April1st to 15thNight
20%10%33%26%7%
539
16th to endNight
19%5%35%27%11%1
540
May1st to 15thNight
21%5%30%30%11%
540
16th to endNight
15%325%34%17%2
563
June1st to 15thNight
11%225%44%15%
540
16th to endNight
7%225%38%23%1
540
July1st to 15thNight
9%17%44%25%2
510
16th to endNight
6%115%40%33%3
564
August1st to 15thNight
4114%47%26%5%
539
16th to endNight
10%112%32%39%3
573
September1st to 15thNight
13%317%30%31%4
631
16th to endNight
14%414%32%29%4
717
October1st to 15thNight
16%6%22%32%19%3
720
16th to endNight
23%11%31%23%10%
768
November1st to 15thNight
17%10%30%27%11%1
760
16th to endNight
26%12%27%25%7%
780
December1st to 15thNight
27%12%31%22%5%
832
16th to endNight
29%11%33%21%3
1040
Page generated at 2018-03-12 13:28:10. Version ac04

Copyright 2018 A. Danko


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