Fiddletown
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fiddletown clear sky chart from 2005-11-05 to 2017-08-12.

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
69%
15113
28%
46504
26%
15078
72%
15078
41%
24902

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%
717
19%
2483
20%
716
66%
716
30%
1414
January16th to endNight
57%
768
24%
2496
24%
768
61%
768
28%
1524
February1st to 15thNight
56%
698
23%
2241
24%
697
60%
697
27%
1394
February16th to endNight
54%
632
25%
1895
23%
632
59%
632
28%
1197
March1st to 15thNight
54%
720
17%
2082
17%
720
56%
720
26%
1381
March16th to endNight
55%
768
20%
2042
16%
768
58%
768
29%
1353
April1st to 15thNight
57%
719
19%
1799
12%
719
59%
719
30%
1218
April16th to endNight
64%
720
24%
1800
13%
720
67%
720
43%
1085
May1st to 15thNight
72%
587
28%
1667
21%
587
74%
587
55%
817
May16th to endNight
78%
374
26%
1496
31%
374
80%
374
42%
666
June1st to 15thNight
80%
360
28%
1440
35%
360
84%
360
49%
586
June16th to endNight
89%
360
37%
1440
50%
360
91%
360
69%
465
July1st to 15thNight
96%
340
34%
1360
47%
340
96%
340
75%
420
July16th to endNight
91%
480
39%
1512
40%
450
92%
450
69%
574
August1st to 15thNight
90%
582
38%
1631
30%
579
90%
579
73%
695
August16th to endNight
93%
700
42%
1750
28%
700
93%
700
82%
788
September1st to 15thNight
92%
660
45%
1650
33%
660
93%
660
82%
739
September16th to endNight
85%
656
43%
1768
38%
656
88%
656
70%
810
October1st to 15thNight
75%
660
31%
1980
33%
660
77%
660
49%
995
October16th to endNight
76%
704
35%
2112
37%
704
80%
704
51%
1053
November1st to 15thNight
73%
700
29%
2264
31%
700
75%
700
42%
1168
November16th to endNight
62%
720
26%
2388
27%
720
66%
720
34%
1329
December1st to 15thNight
57%
720
21%
2520
20%
720
62%
720
26%
1519
December16th to endNight
47%
768
22%
2688
20%
768
53%
768
22%
1712

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%313212335%62%
47468
Night
11%312212335%59%
46695
TransparencyDay
25%37%18%24%20%
47149
Night
27%38%18%23%18%
46514
SeeingDay
12%8%27%33%12%4
5705
Night
13%29%32%33%8%
15124

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
18%5%2223346%49%
1453
16th to endDay
21%7%13323335%44%
1728
February1st to 15thDay
20%5%23323245%46%
1613
16th to endDay
23%8%34312435%39%
1579
March1st to 15thDay
20%7%25%323447%38%
1878
16th to endDay
18%7%15%324436%41%
2181
April1st to 15thDay
17%7%2432335%6%43%
2149
16th to endDay
14%312212346%57%
2160
May1st to 15thDay
6%312213336%65%
2281
16th to endDay
8%314323336%58%
2615
June1st to 15thDay
5%313212235%66%
2520
16th to endDay
11111113283%
2520
July1st to 15thDay
11112285%
2520
16th to endDay
1112112284%
2550
August1st to 15thDay
111112285%
2234
16th to endDay
1111122385%
2100
September1st to 15thDay
1111111385%
1980
16th to endDay
3211222378%
1858
October1st to 15thDay
7%21221345%5%64%
1650
16th to endDay
8%213323335%61%
1760
November1st to 15thDay
9%413324347%54%
1594
16th to endDay
14%5%1333234451%
1569
December1st to 15thDay
19%6%25%32333446%
1440
16th to endDay
24%6%24222347%39%
1536
January1st to 15thNight
17%42331335%7%48%
2483
16th to endNight
18%5%13423335%47%
2496
February1st to 15thNight
17%5%1442445%6%43%
2239
16th to endNight
21%6%2332334446%
1895
March1st to 15thNight
20%7%24323345%42%
2082
16th to endNight
20%5%23213336%46%
2042
April1st to 15thNight
15%5%24424445%44%
1799
16th to endNight
11%412212346%57%
1800
May1st to 15thNight
7%11121225%6%66%
1667
16th to endNight
7%313213337%63%
1496
June1st to 15thNight
422213335%70%
1440
16th to endNight
1121112284%
1440
July1st to 15thNight
11123284%
1440
16th to endNight
111111121283%
1616
August1st to 15thNight
1111123480%
1640
16th to endNight
11112484%
1750
September1st to 15thNight
11112287%
1650
16th to endNight
21111222379%
1768
October1st to 15thNight
7%212312335%66%
1980
16th to endNight
7%21212336%65%
2112
November1st to 15thNight
11%412213346%59%
2264
16th to endNight
13%423423346%53%
2388
December1st to 15thNight
19%5%13323346%46%
2520
16th to endNight
25%6%13313235%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
36%410%20%18%9%
1453
16th to endDay
42%49%14%16%11%
1728
February1st to 15thDay
40%310%20%18%6%
1613
16th to endDay
47%38%24%12%2
1579
March1st to 15thDay
44%5%11%16%16%5%
1878
16th to endDay
43%5%13%18%15%3
2181
April1st to 15thDay
41%411%22%14%4
2149
16th to endDay
28%413%25%23%5%
2160
May1st to 15thDay
19%39%29%30%7%
2281
16th to endDay
26%5%10%28%21%7%
2619
June1st to 15thDay
20%39%22%23%20%
2520
16th to endDay
8%1313%34%37%
2520
July1st to 15thDay
7%127%25%55%
2371
16th to endDay
8%1310%23%52%
2392
August1st to 15thDay
7%129%29%48%
2218
16th to endDay
6%129%38%40%
2100
September1st to 15thDay
7%1210%36%41%
1980
16th to endDay
12%15%21%34%24%
1858
October1st to 15thDay
18%47%24%27%17%
1650
16th to endDay
24%37%23%25%15%
1760
November1st to 15thDay
28%412%22%21%9%
1594
16th to endDay
35%47%19%26%5%
1569
December1st to 15thDay
43%29%19%20%4
1440
16th to endDay
44%410%15%16%7%
1536
January1st to 15thNight
35%411%19%18%10%
2483
16th to endNight
40%38%13%18%15%
2496
February1st to 15thNight
40%48%19%18%9%
2250
16th to endNight
40%49%26%15%4
1895
March1st to 15thNight
43%410%16%17%6%
2082
16th to endNight
40%5%9%20%17%6%
2042
April1st to 15thNight
40%5%13%20%14%5%
1799
16th to endNight
27%6%11%26%21%7%
1800
May1st to 15thNight
18%312%24%28%12%
1668
16th to endNight
21%413%29%21%9%
1496
June1st to 15thNight
16%411%24%22%20%
1440
16th to endNight
9%315%33%37%
1440
July1st to 15thNight
6%136%24%57%
1360
16th to endNight
9%237%22%54%
1512
August1st to 15thNight
8%2213%25%46%
1631
16th to endNight
6%1210%35%44%
1750
September1st to 15thNight
6%139%39%40%
1650
16th to endNight
11%2420%37%25%
1768
October1st to 15thNight
21%36%22%27%18%
1980
16th to endNight
20%36%23%27%17%
2112
November1st to 15thNight
26%312%22%22%13%
2264
16th to endNight
32%37%22%24%9%
2388
December1st to 15thNight
39%410%18%18%8%
2520
16th to endNight
45%39%14%17%9%
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
41%222%20%11%1
81
16th to endDay
27%6%22%23%16%3
256
February1st to 15thDay
23%9%22%30%11%3
243
16th to endDay
27%14%21%24%11%
238
March1st to 15thDay
24%18%21%21%11%2
270
16th to endDay
25%13%30%19%11%
288
April1st to 15thDay
23%17%31%18%5%2
269
16th to endDay
16%19%28%23%10%1
270
May1st to 15thDay
9%12%38%26%8%4
288
16th to endDay
10%14%21%32%14%6%
330
June1st to 15thDay
9%13%31%33%8%5%
315
16th to endDay
2333%42%11%7%
315
July1st to 15thDay
23%53%11%10%
305
16th to endDay
129%47%13%7%
327
August1st to 15thDay
2134%43%11%6%
300
16th to endDay
229%48%11%7%
268
September1st to 15thDay
2229%44%16%4
255
16th to endDay
48%25%40%18%2
255
October1st to 15thDay
6%9%33%32%14%3
255
16th to endDay
13%9%27%27%20%1
272
November1st to 15thDay
10%5%11%28%35%11%
100
16th to endDay
16%12%18%34%17%1
81
December1st to 15thDay
28%6%33%18%11%1
60
16th to endDay
25%120%26%18%7%
64
January1st to 15thNight
18%39%33%25%10%
720
16th to endNight
21%211%30%24%10%
768
February1st to 15thNight
19%212%32%25%6%
704
16th to endNight
23%413%31%21%6%
632
March1st to 15thNight
21%5%10%30%25%6%
720
16th to endNight
21%414%29%26%5%
768
April1st to 15thNight
19%411%37%23%3
719
16th to endNight
12%313%35%26%8%
720
May1st to 15thNight
9%113%37%32%5%
588
16th to endNight
8%27%31%45%5%
375
June1st to 15thNight
5%9%33%44%6%
360
16th to endNight
1435%51%6%
360
July1st to 15thNight
29%63%5%
340
16th to endNight
21225%56%13%
480
August1st to 15thNight
2332%53%8%
582
16th to endNight
1335%51%8%
700
September1st to 15thNight
1329%52%12%
660
16th to endNight
27%33%39%16%
656
October1st to 15thNight
8%29%35%32%12%
660
16th to endNight
8%110%29%34%15%
704
November1st to 15thNight
13%17%34%31%11%
700
16th to endNight
15%213%32%25%10%
720
December1st to 15thNight
22%310%34%22%7%
720
16th to endNight
29%213%28%19%5%
768
Page generated at 2017-08-13 11:16:29. Version ac04

Copyright 2017 A. Danko


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