Woodland Trails
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Woodland Trails clear sky chart from 2005-11-05 to

2017-09-12
.

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
30%
14773
14%
46712
8%
14737
37%
14737
17%
32895

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
13%
719
9%
2488
2%
716
22%
716
7%
1972
January16th to endNight
17%
768
10%
2496
3%
768
25%
768
9%
1986
February1st to 15thNight
13%
701
10%
2287
2%
701
23%
701
10%
1782
February16th to endNight
17%
631
12%
2020
4%
631
26%
631
12%
1496
March1st to 15thNight
19%
720
13%
1980
5%
720
28%
720
14%
1497
March16th to endNight
26%
768
20%
2112
9%
768
36%
768
22%
1445
April1st to 15thNight
21%
718
15%
1814
4%
718
28%
718
20%
1331
April16th to endNight
32%
564
19%
1644
8%
564
40%
564
25%
1083
May1st to 15thNight
42%
477
17%
1557
11%
477
49%
477
21%
1024
May16th to endNight
42%
374
17%
1497
14%
374
53%
374
25%
828
June1st to 15thNight
38%
360
12%
1440
11%
360
47%
360
19%
864
June16th to endNight
46%
360
12%
1338
14%
360
52%
360
25%
794
July1st to 15thNight
57%
340
16%
1336
20%
340
64%
340
33%
690
July16th to endNight
56%
472
16%
1506
15%
442
60%
442
30%
874
August1st to 15thNight
58%
539
17%
1609
12%
536
62%
536
36%
949
August16th to endNight
55%
626
23%
1772
13%
626
61%
626
35%
1060
September1st to 15thNight
47%
707
19%
1771
8%
707
52%
707
33%
1157
September16th to endNight
51%
657
21%
1840
14%
657
55%
657
31%
1163
October1st to 15thNight
35%
660
17%
1980
13%
660
42%
660
20%
1379
October16th to endNight
20%
704
11%
2112
4%
704
29%
704
13%
1620
November1st to 15thNight
29%
700
18%
2385
15%
700
36%
700
18%
1647
November16th to endNight
23%
720
10%
2520
6%
720
29%
720
11%
1935
December1st to 15thNight
12%
720
6%
2520
2%
720
17%
720
7%
2060
December16th to endNight
10%
768
5%
2688
1%
768
15%
768
6%
2259

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
15%8%47%6%35%5%5%6%31%
47921
Night
15%9%47%5%3445%6%33%
46891
Cloud CoverDay
15%8%36%6%35%5%5%7%31%
47931
Night
15%8%36%5%35%45%6%34%
46895
TransparencyDay
50%7%11%18%10%
47618
Night
49%7%11%19%10%1
46712
SeeingDay
18%11%30%23%11%5%
5430
Night
20%11%31%25%10%1
14778

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
17%14%5%9%7%445%45%21%
1447
16th to endDay
14%14%7%11%7%46%5%5%5%17%
1728
February1st to 15thDay
13%16%7%11%8%45%345%19%
1575
16th to endDay
16%14%6%8%6%2445%425%
1449
March1st to 15thDay
13%12%48%8%5%6%35%427%
1969
16th to endDay
16%8%46%5%33445%36%
2112
April1st to 15thDay
21%9%46%5%2435%5%29%
2134
16th to endDay
17%8%35%5%23446%38%
2325
May1st to 15thDay
15%7%36%6%35%45%7%34%
2392
16th to endDay
13%6%26%6%3445%7%39%
2618
June1st to 15thDay
17%6%35%5%35%5%5%8%34%
2520
16th to endDay
14%5%25%6%35%5%6%9%35%
2611
July1st to 15thDay
9%426%436%5%6%9%39%
2535
16th to endDay
10%5%27%6%36%6%7%9%34%
2556
August1st to 15thDay
9%5%37%6%35%5%6%8%37%
2340
16th to endDay
12%6%25%5%345%6%8%37%
2417
September1st to 15thDay
15%5%25%5%35%45%6%38%
2108
16th to endDay
14%6%46%5%3445%6%39%
1788
October1st to 15thDay
20%7%37%6%25%345%32%
1650
16th to endDay
24%12%5%8%5%34445%21%
1760
November1st to 15thDay
15%11%37%6%245%46%29%
1471
16th to endDay
18%12%6%9%7%446%45%19%
1440
December1st to 15thDay
17%15%6%12%8%35%5%5%5%14%
1440
16th to endDay
19%13%7%11%7%35%5%5%6%14%
1536
January1st to 15thNight
18%14%6%9%6%3445%5%19%
2488
16th to endNight
13%13%7%10%7%46%5%5%6%19%
2496
February1st to 15thNight
13%15%5%8%7%36%5%5%5%21%
2285
16th to endNight
13%11%49%6%5%5%46%5%27%
2020
March1st to 15thNight
16%10%5%7%7%35%33431%
1968
16th to endNight
14%7%46%4235%4441%
2112
April1st to 15thNight
19%8%35%435%345%34%
1814
16th to endNight
12%8%37%42335%6%42%
1644
May1st to 15thNight
16%425%5%345%6%7%38%
1557
16th to endNight
12%41442445%7%49%
1495
June1st to 15thNight
12%6%25%5%25%5%5%7%40%
1440
16th to endNight
11%425%5%3445%9%43%
1338
July1st to 15thNight
6%414425%446%55%
1416
16th to endNight
6%4245%345%6%8%48%
1610
August1st to 15thNight
6%5%1442447%9%49%
1620
16th to endNight
7%5%2443445%6%52%
1772
September1st to 15thNight
13%42443435%7%45%
1771
16th to endNight
13%5%3442335%6%46%
1840
October1st to 15thNight
17%7%27%5%2345%6%37%
1980
16th to endNight
23%9%26%6%35%5%5%6%25%
2112
November1st to 15thNight
17%8%36%5%345%46%34%
2385
16th to endNight
19%11%5%8%5%35%5%5%6%23%
2520
December1st to 15thNight
18%14%5%9%7%45%5%45%17%
2520
16th to endNight
20%13%7%10%8%45%5%5%5%14%
2688

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
17%14%48%7%35%446%22%
1447
16th to endDay
13%14%7%10%8%46%5%5%5%17%
1728
February1st to 15thDay
13%16%7%9%8%44345%20%
1575
16th to endDay
16%15%5%8%5%3445%426%
1449
March1st to 15thDay
15%10%47%7%5%5%445%27%
1980
16th to endDay
16%8%45%5%24445%36%
2111
April1st to 15thDay
21%9%45%5%3445%5%29%
2134
16th to endDay
17%7%25%5%24446%37%
2325
May1st to 15thDay
15%6%37%6%345%5%7%34%
2392
16th to endDay
13%5%26%5%345%6%7%39%
2618
June1st to 15thDay
16%5%345%36%5%5%8%34%
2520
16th to endDay
13%5%25%5%36%5%6%9%35%
2611
July1st to 15thDay
9%5%25%5%46%5%7%9%40%
2535
16th to endDay
10%5%36%6%36%5%7%9%34%
2556
August1st to 15thDay
9%5%25%6%45%6%6%9%37%
2340
16th to endDay
12%6%25%5%35%5%6%8%38%
2417
September1st to 15thDay
15%5%25%4345%5%7%38%
2108
16th to endDay
14%6%46%5%35%45%6%39%
1788
October1st to 15thDay
20%6%36%6%345%45%33%
1650
16th to endDay
24%11%47%5%3445%5%22%
1760
November1st to 15thDay
15%9%46%6%345%5%7%30%
1471
16th to endDay
18%12%5%8%7%45%5%46%20%
1440
December1st to 15thDay
18%14%6%10%9%35%5%5%6%15%
1440
16th to endDay
19%12%7%9%6%45%6%47%15%
1536
January1st to 15thNight
20%14%6%7%6%34446%20%
2488
16th to endNight
13%13%6%9%7%46%5%46%21%
2496
February1st to 15thNight
13%14%5%8%6%35%5%5%6%23%
2278
16th to endNight
14%11%48%6%445%5%6%28%
2020
March1st to 15thNight
17%11%47%6%3433431%
1980
16th to endNight
14%8%45%425%445%41%
2112
April1st to 15thNight
19%8%25%5%35%346%34%
1814
16th to endNight
12%7%35%5%3345%6%42%
1644
May1st to 15thNight
15%4345%35%46%8%37%
1556
16th to endNight
12%414325%45%7%49%
1495
June1st to 15thNight
12%6%25%5%25%45%8%40%
1440
16th to endNight
11%5%25%5%3445%9%43%
1338
July1st to 15thNight
6%3233245%5%7%54%
1416
16th to endNight
6%4235%35%5%6%8%48%
1610
August1st to 15thNight
6%4145%2445%10%49%
1620
16th to endNight
7%424435%45%6%52%
1772
September1st to 15thNight
14%41442445%7%46%
1771
16th to endNight
13%5%25%42336%7%47%
1840
October1st to 15thNight
17%7%27%5%245%46%37%
1980
16th to endNight
22%8%36%6%35%45%6%26%
2112
November1st to 15thNight
18%7%25%5%3435%7%34%
2385
16th to endNight
19%10%47%5%35%5%5%6%25%
2520
December1st to 15thNight
19%14%5%8%7%35%5%5%6%18%
2520
16th to endNight
21%12%6%8%7%46%5%46%15%
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
62%8%10%12%6%
1448
16th to endDay
65%7%9%10%6%
1728
February1st to 15thDay
65%7%8%14%3
1577
16th to endDay
59%7%9%15%7%
1449
March1st to 15thDay
57%6%11%16%7%
1980
16th to endDay
48%6%10%17%15%1
2112
April1st to 15thDay
54%5%10%17%11%
2134
16th to endDay
46%6%10%20%15%1
2325
May1st to 15thDay
47%6%9%21%13%
2392
16th to endDay
42%7%12%21%13%1
2622
June1st to 15thDay
45%7%12%21%12%
2520
16th to endDay
43%8%13%20%13%
2611
July1st to 15thDay
38%8%12%23%15%1
2386
16th to endDay
43%8%14%21%10%1
2397
August1st to 15thDay
40%9%13%19%13%1
2327
16th to endDay
41%7%13%25%11%1
2417
September1st to 15thDay
41%8%14%23%10%
2108
16th to endDay
45%6%10%27%9%
1788
October1st to 15thDay
52%6%10%19%9%1
1650
16th to endDay
61%8%13%11%4
1760
November1st to 15thDay
52%8%12%17%8%1
1471
16th to endDay
61%9%13%10%4
1440
December1st to 15thDay
66%9%12%9%1
1440
16th to endDay
67%9%9%10%2
1536
January1st to 15thNight
64%6%10%11%6%
2488
16th to endNight
61%9%9%14%4
2496
February1st to 15thNight
59%8%9%16%5%
2287
16th to endNight
54%7%12%17%7%
2020
March1st to 15thNight
56%5%11%19%7%
1980
16th to endNight
44%6%9%21%16%1
2112
April1st to 15thNight
51%310%18%14%
1814
16th to endNight
41%6%10%20%17%3
1644
May1st to 15thNight
43%7%10%21%15%2
1557
16th to endNight
34%6%14%26%15%2
1497
June1st to 15thNight
40%6%10%25%15%1
1440
16th to endNight
37%6%13%23%17%1
1338
July1st to 15thNight
27%6%11%28%23%1
1336
16th to endNight
32%7%12%27%16%2
1506
August1st to 15thNight
30%6%18%28%14%1
1609
16th to endNight
31%6%11%32%16%1
1772
September1st to 15thNight
35%6%15%26%14%1
1771
16th to endNight
35%6%12%30%13%
1840
October1st to 15thNight
46%7%10%21%13%
1980
16th to endNight
56%8%12%14%7%
2112
November1st to 15thNight
49%6%11%18%12%1
2385
16th to endNight
57%9%14%13%4
2520
December1st to 15thNight
65%9%10%11%3
2520
16th to endNight
68%9%10%8%3
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
19%26%31%15%6%
63
16th to endDay
33%22%31%11%1
96
February1st to 15thDay
21%30%40%8%
90
16th to endDay
24%25%34%11%3
93
March1st to 15thDay
23%18%34%19%4
270
16th to endDay
22%14%36%16%6%2
288
April1st to 15thDay
24%16%34%15%7%1
270
16th to endDay
20%14%34%17%9%4
270
May1st to 15thDay
19%12%27%24%9%6%
288
16th to endDay
17%11%30%24%12%2
331
June1st to 15thDay
20%11%25%29%10%1
315
16th to endDay
16%7%33%29%10%2
406
July1st to 15thDay
11%5%25%32%17%6%
320
16th to endDay
9%7%28%31%14%8%
326
August1st to 15thDay
11%5%25%28%16%12%
313
16th to endDay
13%325%25%18%13%
332
September1st to 15thDay
11%6%24%25%21%11%
299
16th to endDay
16%5%24%28%16%9%
254
October1st to 15thDay
18%9%31%21%13%5%
255
16th to endDay
30%14%31%17%5%
272
November1st to 15thDay
15%11%34%25%9%3
95
16th to endDay
30%25%28%11%5%
60
December1st to 15thDay
23%23%31%15%6%
60
16th to endDay
31%21%42%4
64
January1st to 15thNight
27%20%33%13%3
720
16th to endNight
21%13%37%22%5%
768
February1st to 15thNight
21%18%38%18%3
704
16th to endNight
20%17%36%20%4
631
March1st to 15thNight
24%16%34%20%3
720
16th to endNight
19%13%35%21%8%1
768
April1st to 15thNight
23%14%36%20%4
718
16th to endNight
17%14%31%26%8%
564
May1st to 15thNight
18%6%27%33%12%1
477
16th to endNight
12%6%33%29%17%1
375
June1st to 15thNight
15%8%30%33%12%
360
16th to endNight
13%430%37%13%
360
July1st to 15thNight
9%325%42%18%1
340
16th to endNight
8%326%40%18%2
472
August1st to 15thNight
8%221%39%26%2
539
16th to endNight
10%324%34%23%3
626
September1st to 15thNight
15%5%25%27%20%3
707
16th to endNight
16%5%20%34%19%3
657
October1st to 15thNight
22%9%27%26%12%1
660
16th to endNight
26%13%33%21%5%
704
November1st to 15thNight
22%11%32%22%9%1
700
16th to endNight
26%15%28%23%6%
720
December1st to 15thNight
28%16%36%14%3
720
16th to endNight
28%13%39%15%1
768
Page generated at 2017-09-13 07:39:08. Version ac04

Copyright 2017 A. Danko


Woodland Trails Clear Sky Chart | Charts Home