Fremont Peak
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fremont Peak 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
67%
16185
26%
49132
24%
16149
69%
16149
36%
27963

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
63%
776
19%
2580
20%
776
65%
776
28%
1563
January16th to endNight
62%
832
23%
2704
26%
832
64%
832
28%
1671
February1st to 15thNight
63%
760
26%
2448
27%
760
66%
760
28%
1486
February16th to endNight
56%
684
24%
2051
22%
684
61%
684
29%
1275
March1st to 15thNight
56%
764
18%
2153
17%
764
58%
764
28%
1419
March16th to endNight
56%
768
20%
2073
16%
768
59%
768
30%
1365
April1st to 15thNight
53%
719
22%
1799
14%
719
55%
719
32%
1201
April16th to endNight
60%
720
24%
1800
12%
720
63%
720
43%
1072
May1st to 15thNight
66%
673
22%
1753
15%
673
67%
673
41%
1041
May16th to endNight
63%
388
22%
1511
21%
388
67%
388
27%
819
June1st to 15thNight
67%
360
23%
1440
26%
360
71%
360
30%
743
June16th to endNight
81%
360
31%
1440
40%
360
83%
360
52%
560
July1st to 15thNight
82%
382
27%
1402
32%
382
82%
382
48%
604
July16th to endNight
73%
564
28%
1593
25%
531
74%
531
45%
806
August1st to 15thNight
71%
595
25%
1668
19%
592
71%
592
44%
901
August16th to endNight
80%
764
32%
1910
21%
764
80%
764
59%
1016
September1st to 15thNight
82%
720
37%
1800
27%
720
83%
720
61%
940
September16th to endNight
79%
716
40%
1947
37%
716
80%
716
56%
983
October1st to 15thNight
76%
720
28%
2160
31%
720
78%
720
47%
1114
October16th to endNight
72%
768
34%
2304
37%
768
74%
768
42%
1247
November1st to 15thNight
69%
760
28%
2380
30%
760
71%
760
38%
1295
November16th to endNight
67%
780
26%
2574
28%
780
69%
780
34%
1416
December1st to 15thNight
63%
780
24%
2730
25%
780
66%
780
28%
1617
December16th to endNight
54%
832
22%
2912
21%
832
58%
832
23%
1809

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
7%5%24323347%56%
49497
Night
7%5%24423447%51%
49320
TransparencyDay
27%48%18%23%17%
49185
Night
30%49%17%21%15%
49133
SeeingDay
9%8%26%33%16%4
6589
Night
9%311%31%33%11%
16195

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
12%7%35%423447%44%
1685
16th to endDay
14%7%26%413435%45%
1872
February1st to 15thDay
13%7%24413346%47%
1745
16th to endDay
15%8%36%41445%6%40%
1709
March1st to 15thDay
12%5%35%435%5%6%9%38%
2042
16th to endDay
11%7%35%6%245%47%41%
2151
April1st to 15thDay
11%7%45%433447%43%
2149
16th to endDay
8%5%24323346%54%
2160
May1st to 15thDay
4423223448%59%
2195
16th to endDay
6%7%2442435%8%50%
2599
June1st to 15thDay
45%24323347%57%
2520
16th to endDay
1212212236%72%
2520
July1st to 15thDay
212323237%69%
2472
16th to endDay
1212312237%69%
2468
August1st to 15thDay
1424413238%64%
2283
16th to endDay
212213348%69%
2292
September1st to 15thDay
1312212137%73%
2160
16th to endDay
3312212335%69%
2010
October1st to 15thDay
5%313323336%64%
1800
16th to endDay
5%414414245%62%
1920
November1st to 15thDay
8%5%25%423346%53%
1808
16th to endDay
10%42342335%6%51%
1713
December1st to 15thDay
13%8%25%5%1444444%
1560
16th to endDay
14%7%2442345%6%43%
1664
January1st to 15thNight
11%6%2442345%8%45%
2580
16th to endNight
13%5%25%424446%46%
2704
February1st to 15thNight
11%6%2433445%6%46%
2437
16th to endNight
13%6%3442335%7%45%
2051
March1st to 15thNight
11%8%36%423447%43%
2153
16th to endNight
10%8%35%4235%47%44%
2073
April1st to 15thNight
11%5%345%2445%6%45%
1799
16th to endNight
7%5%23313348%57%
1800
May1st to 15thNight
35%25%5%34447%53%
1753
16th to endNight
47%46%423446%51%
1510
June1st to 15thNight
46%36%3345%5%7%50%
1440
16th to endNight
1224322336%65%
1440
July1st to 15thNight
132443435%8%58%
1485
16th to endNight
16%27%5%345%5%9%49%
1701
August1st to 15thNight
6%37%7%35%447%48%
1677
16th to endNight
425%43445%8%56%
1910
September1st to 15thNight
2313313346%65%
1800
16th to endNight
2412412227%67%
1947
October1st to 15thNight
7%412322246%61%
2160
16th to endNight
6%5%15%32335%5%58%
2304
November1st to 15thNight
7%5%24323336%56%
2380
16th to endNight
8%434323348%51%
2574
December1st to 15thNight
12%6%24423446%47%
2730
16th to endNight
16%6%24423446%44%
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
39%49%20%16%9%
1685
16th to endDay
41%5%7%13%19%11%
1872
February1st to 15thDay
38%48%19%22%7%
1745
16th to endDay
45%5%8%22%14%3
1709
March1st to 15thDay
40%7%11%18%16%4
2042
16th to endDay
41%6%14%17%16%2
2151
April1st to 15thDay
41%5%10%23%16%2
2149
16th to endDay
29%6%12%24%20%6%
2160
May1st to 15thDay
21%5%10%27%27%6%
2195
16th to endDay
30%6%10%24%22%5%
2603
June1st to 15thDay
25%5%10%19%24%15%
2520
16th to endDay
11%27%16%30%31%
2520
July1st to 15thDay
13%25%7%22%48%
2327
16th to endDay
11%35%10%25%42%
2313
August1st to 15thDay
15%2412%26%38%
2267
16th to endDay
10%25%14%33%33%
2292
September1st to 15thDay
11%3413%31%35%
2160
16th to endDay
16%2423%34%17%
2010
October1st to 15thDay
20%5%7%20%25%21%
1800
16th to endDay
23%48%20%23%19%
1920
November1st to 15thDay
32%410%20%24%7%
1808
16th to endDay
33%49%18%27%6%
1713
December1st to 15thDay
41%410%13%18%12%
1560
16th to endDay
41%411%16%18%7%
1664
January1st to 15thNight
37%5%10%18%19%7%
2580
16th to endNight
39%410%13%17%13%
2704
February1st to 15thNight
37%5%8%17%22%9%
2448
16th to endNight
38%411%25%15%4
2051
March1st to 15thNight
41%5%12%17%16%7%
2153
16th to endNight
39%6%12%18%16%6%
2073
April1st to 15thNight
38%6%12%24%15%3
1799
16th to endNight
27%5%13%24%21%7%
1800
May1st to 15thNight
28%5%9%19%26%10%
1754
16th to endNight
33%5%11%19%24%5%
1511
June1st to 15thNight
28%7%11%14%20%17%
1440
16th to endNight
16%26%12%28%33%
1440
July1st to 15thNight
18%45%8%19%43%
1402
16th to endNight
23%38%11%17%35%
1593
August1st to 15thNight
26%36%13%18%31%
1668
16th to endNight
17%37%12%25%31%
1910
September1st to 15thNight
17%3411%26%37%
1800
16th to endNight
18%3318%32%22%
1947
October1st to 15thNight
23%38%20%21%23%
2160
16th to endNight
26%46%19%23%19%
2304
November1st to 15thNight
29%411%20%26%8%
2380
16th to endNight
31%410%18%25%9%
2574
December1st to 15thNight
36%5%8%15%20%12%
2730
16th to endNight
41%5%10%16%18%7%
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
21%7%24%27%17%
223
16th to endDay
17%7%23%28%20%1
304
February1st to 15thDay
14%9%24%24%22%4
290
16th to endDay
18%14%27%27%10%2
290
March1st to 15thDay
19%14%26%24%12%2
312
16th to endDay
14%17%36%22%7%1
288
April1st to 15thDay
17%21%31%21%8%
269
16th to endDay
11%19%36%24%6%2
270
May1st to 15thDay
9%14%38%29%5%2
288
16th to endDay
11%13%30%28%11%4
330
June1st to 15thDay
6%7%41%29%9%5%
315
16th to endDay
1327%40%20%5%
315
July1st to 15thDay
120%48%20%7%
305
16th to endDay
1117%52%18%9%
327
August1st to 15thDay
2321%47%18%6%
315
16th to endDay
118%48%20%10%
332
September1st to 15thDay
3222%43%19%8%
315
16th to endDay
6%6%20%37%23%6%
315
October1st to 15thDay
5%10%28%34%16%3
315
16th to endDay
9%6%25%32%20%6%
336
November1st to 15thDay
8%5%19%32%25%8%
224
16th to endDay
11%416%37%27%2
125
December1st to 15thDay
15%5%22%30%23%3
90
16th to endDay
16%6%11%29%29%7%
96
January1st to 15thNight
14%38%34%28%9%
780
16th to endNight
15%410%31%29%9%
832
February1st to 15thNight
14%410%31%29%8%
764
16th to endNight
16%5%12%36%23%6%
684
March1st to 15thNight
14%412%34%26%7%
764
16th to endNight
13%5%16%35%25%4
768
April1st to 15thNight
12%5%18%36%23%3
719
16th to endNight
8%6%19%30%26%8%
720
May1st to 15thNight
4216%38%28%9%
674
16th to endNight
7%5%14%31%31%8%
389
June1st to 15thNight
7%314%35%32%7%
360
16th to endNight
36%34%46%7%
360
July1st to 15thNight
26%18%55%16%
382
16th to endNight
210%13%49%23%
564
August1st to 15thNight
329%22%50%13%
595
16th to endNight
27%22%52%15%
764
September1st to 15thNight
45%21%51%16%
720
16th to endNight
416%28%40%17%
716
October1st to 15thNight
7%27%36%32%13%
720
16th to endNight
8%28%27%32%21%
768
November1st to 15thNight
9%110%35%30%13%
760
16th to endNight
10%210%34%32%10%
780
December1st to 15thNight
13%410%35%28%7%
780
16th to endNight
18%5%13%34%22%5%
832
Page generated at 2018-03-12 10:28:06. Version ac04

Copyright 2018 A. Danko


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