James Baird State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the James Baird State Park 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
32%
14800
18%
46472
9%
14768
42%
14768
20%
30745

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
21%
720
19%
2506
7%
716
35%
716
16%
1631
January16th to endNight
19%
768
19%
2626
6%
768
36%
768
16%
1700
February1st to 15thNight
17%
704
15%
2229
3%
701
32%
701
15%
1542
February16th to endNight
18%
631
21%
1893
8%
631
34%
631
18%
1262
March1st to 15thNight
22%
720
17%
2160
7%
720
33%
720
16%
1492
March16th to endNight
22%
768
22%
1990
7%
768
34%
768
20%
1364
April1st to 15thNight
20%
718
16%
1796
4%
718
27%
718
18%
1318
April16th to endNight
27%
681
17%
1761
4%
681
35%
681
23%
1231
May1st to 15thNight
26%
490
17%
1570
7%
490
36%
490
16%
1076
May16th to endNight
40%
375
14%
1497
12%
374
48%
374
18%
950
June1st to 15thNight
41%
360
13%
1440
10%
360
52%
360
16%
947
June16th to endNight
51%
360
13%
1440
15%
360
58%
360
26%
823
July1st to 15thNight
52%
340
13%
1360
16%
340
56%
340
21%
817
July16th to endNight
55%
376
15%
1418
18%
354
59%
354
22%
843
August1st to 15thNight
55%
500
17%
1549
12%
498
60%
498
30%
958
August16th to endNight
57%
700
18%
1750
10%
700
59%
700
32%
1182
September1st to 15thNight
45%
660
23%
1650
11%
660
50%
660
32%
1091
September16th to endNight
48%
657
25%
1812
17%
657
54%
657
33%
1121
October1st to 15thNight
38%
660
21%
1923
15%
660
47%
660
25%
1263
October16th to endNight
29%
704
17%
2216
8%
704
41%
704
19%
1496
November1st to 15thNight
32%
700
20%
2277
10%
700
46%
700
21%
1460
November16th to endNight
29%
720
19%
2401
10%
720
39%
720
17%
1588
December1st to 15thNight
25%
720
15%
2520
6%
720
36%
720
15%
1719
December16th to endNight
17%
768
16%
2688
4%
768
31%
768
14%
1871

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%6%25%5%345%5%7%38%
47506
Night
16%6%25%42445%6%39%
46642
Cloud CoverDay
16%6%25%5%3445%7%38%
47515
Night
16%6%25%5%24446%39%
46648
TransparencyDay
44%6%11%21%13%1
47194
Night
43%6%12%21%14%1
46472
SeeingDay
20%12%26%23%12%4
5615
Night
20%12%29%26%9%
14800

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
14%6%246%46%5%5%5%37%
1432
16th to endDay
13%6%35%5%345%5%8%37%
1596
February1st to 15thDay
16%7%37%5%35%5%5%6%33%
1630
16th to endDay
15%7%35%6%2445%6%37%
1580
March1st to 15thDay
16%8%36%5%35%5%5%5%34%
1790
16th to endDay
16%8%35%5%23345%40%
2230
April1st to 15thDay
19%8%35%423446%37%
2152
16th to endDay
17%5%245%24346%43%
2199
May1st to 15thDay
20%7%35%5%2445%6%33%
2391
16th to endDay
15%6%35%425%5%6%8%36%
2618
June1st to 15thDay
21%425%435%5%6%8%33%
2520
16th to endDay
12%5%26%6%35%6%6%8%36%
2520
July1st to 15thDay
10%6%26%5%35%6%5%9%38%
2520
16th to endDay
11%425%5%45%6%6%9%38%
2654
August1st to 15thDay
12%5%24435%7%6%8%39%
2301
16th to endDay
11%5%26%4245%6%8%42%
2100
September1st to 15thDay
14%5%24425%5%5%5%43%
1980
16th to endDay
13%425%324346%48%
1818
October1st to 15thDay
19%6%24433345%42%
1705
16th to endDay
19%6%25%5%345%45%37%
1656
November1st to 15thDay
17%6%24423346%43%
1581
16th to endDay
18%6%2442335%6%41%
1557
December1st to 15thDay
18%7%45%424446%35%
1440
16th to endDay
19%9%35%5%35%445%31%
1536
January1st to 15thNight
16%6%36%5%24446%38%
2506
16th to endNight
14%8%34435%45%7%37%
2626
February1st to 15thNight
13%9%37%6%35%5%45%35%
2228
16th to endNight
15%7%36%5%24445%39%
1893
March1st to 15thNight
18%7%2443445%5%37%
2147
16th to endNight
16%7%26%334445%41%
1990
April1st to 15thNight
19%7%36%5%24446%34%
1796
16th to endNight
18%7%35%423435%42%
1761
May1st to 15thNight
18%7%25%435%345%37%
1570
16th to endNight
16%5%24425%46%9%37%
1495
June1st to 15thNight
20%423435%5%47%38%
1440
16th to endNight
10%425%32448%9%44%
1440
July1st to 15thNight
11%5%245%25%5%6%8%41%
1440
16th to endNight
10%5%25%5%345%7%8%42%
1514
August1st to 15thNight
9%4245%246%6%7%45%
1559
16th to endNight
14%41442445%6%44%
1750
September1st to 15thNight
14%5%24432337%47%
1650
16th to endNight
13%5%2332335%5%51%
1812
October1st to 15thNight
17%5%35%423345%44%
1923
16th to endNight
19%7%25%5%23346%38%
2216
November1st to 15thNight
17%8%35%414345%42%
2277
16th to endNight
18%7%35%5%2345%6%37%
2401
December1st to 15thNight
21%7%35%43445%5%34%
2520
16th to endNight
20%8%26%5%3435%6%31%
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
14%5%25%5%46%5%5%6%37%
1432
16th to endDay
13%6%36%5%25%46%7%38%
1596
February1st to 15thDay
16%8%36%5%35%5%5%7%33%
1630
16th to endDay
15%7%35%5%3445%7%37%
1580
March1st to 15thDay
17%8%37%5%25%45%5%34%
1800
16th to endDay
17%7%35%5%23345%40%
2229
April1st to 15thDay
19%7%35%423435%37%
2152
16th to endDay
16%5%24424446%43%
2199
May1st to 15thDay
21%6%35%425%35%7%34%
2391
16th to endDay
15%5%36%435%5%5%7%36%
2618
June1st to 15thDay
21%5%24435%5%6%7%33%
2520
16th to endDay
12%5%36%6%35%6%6%8%35%
2520
July1st to 15thDay
10%5%35%6%35%6%5%8%37%
2520
16th to endDay
11%425%6%35%5%6%8%38%
2654
August1st to 15thDay
12%5%245%35%6%7%8%38%
2301
16th to endDay
12%5%25%3345%7%7%42%
2100
September1st to 15thDay
13%5%24436%45%6%43%
1980
16th to endDay
13%42442345%6%48%
1818
October1st to 15thDay
18%6%24424345%42%
1705
16th to endDay
18%6%25%5%345%45%37%
1656
November1st to 15thDay
17%6%24423347%44%
1581
16th to endDay
18%6%15%423446%42%
1557
December1st to 15thDay
18%7%36%5%25%346%36%
1440
16th to endDay
20%9%25%5%245%5%5%31%
1536
January1st to 15thNight
16%7%35%5%24437%38%
2506
16th to endNight
15%8%345%3445%7%38%
2626
February1st to 15thNight
13%8%37%5%36%446%35%
2221
16th to endNight
14%7%35%6%34446%40%
1893
March1st to 15thNight
18%6%25%5%25%45%6%37%
2160
16th to endNight
16%7%35%424445%41%
1990
April1st to 15thNight
18%7%36%5%34446%34%
1796
16th to endNight
17%6%25%424335%42%
1761
May1st to 15thNight
18%6%35%434446%37%
1570
16th to endNight
15%6%14435%46%9%38%
1495
June1st to 15thNight
19%5%244245%47%39%
1440
16th to endNight
10%43442447%9%44%
1440
July1st to 15thNight
11%5%25%5%25%5%5%9%40%
1440
16th to endNight
10%5%25%425%47%9%41%
1514
August1st to 15thNight
10%3245%25%6%5%7%46%
1559
16th to endNight
14%4145%245%5%7%44%
1750
September1st to 15thNight
14%5%24423346%48%
1650
16th to endNight
13%5%13323346%50%
1812
October1st to 15thNight
16%5%35%423335%44%
1923
16th to endNight
18%6%35%5%24346%38%
2216
November1st to 15thNight
17%8%25%323345%42%
2277
16th to endNight
17%7%35%433446%37%
2401
December1st to 15thNight
20%7%36%42445%6%34%
2520
16th to endNight
19%9%36%5%3435%6%32%
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
45%5%12%22%11%1
1433
16th to endDay
42%7%13%23%12%1
1596
February1st to 15thDay
49%6%12%18%12%1
1633
16th to endDay
45%411%23%12%1
1580
March1st to 15thDay
49%5%13%20%9%1
1800
16th to endDay
45%49%18%18%3
2230
April1st to 15thDay
48%49%21%13%3
2152
16th to endDay
41%49%22%19%3
2199
May1st to 15thDay
49%6%9%19%13%2
2391
16th to endDay
44%8%12%19%12%1
2622
June1st to 15thDay
48%8%12%19%10%1
2520
16th to endDay
43%9%12%23%11%
2520
July1st to 15thDay
42%9%11%19%15%1
2371
16th to endDay
41%7%13%22%13%1
2487
August1st to 15thDay
39%8%15%22%13%
2287
16th to endDay
37%7%11%24%17%
2100
September1st to 15thDay
40%7%9%21%19%1
1980
16th to endDay
36%6%9%22%23%1
1818
October1st to 15thDay
43%5%10%23%14%2
1705
16th to endDay
46%5%12%22%11%1
1656
November1st to 15thDay
41%414%21%15%2
1581
16th to endDay
43%311%26%12%2
1557
December1st to 15thDay
49%415%19%10%
1440
16th to endDay
51%6%14%17%9%
1536
January1st to 15thNight
44%6%13%20%12%2
2506
16th to endNight
45%5%10%23%13%2
2626
February1st to 15thNight
48%6%12%18%11%2
2229
16th to endNight
44%5%10%20%16%2
1893
March1st to 15thNight
45%7%12%19%12%2
2160
16th to endNight
43%5%9%19%17%3
1990
April1st to 15thNight
49%6%8%19%14%1
1796
16th to endNight
44%5%7%20%18%2
1761
May1st to 15thNight
48%6%9%18%14%2
1570
16th to endNight
43%7%16%18%12%1
1497
June1st to 15thNight
45%8%13%19%11%1
1440
16th to endNight
34%8%16%27%12%1
1440
July1st to 15thNight
38%8%12%24%14%1
1360
16th to endNight
38%7%15%22%13%2
1418
August1st to 15thNight
34%8%15%25%15%1
1549
16th to endNight
37%8%11%24%17%
1750
September1st to 15thNight
38%5%10%26%18%
1650
16th to endNight
34%5%7%22%27%
1812
October1st to 15thNight
41%5%10%21%17%2
1923
16th to endNight
46%5%12%22%12%
2216
November1st to 15thNight
43%5%11%19%16%3
2277
16th to endNight
46%5%12%22%10%1
2401
December1st to 15thNight
48%6%14%19%10%
2520
16th to endNight
51%5%13%18%10%
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
20%33%26%15%5%
60
16th to endDay
18%24%39%17%
74
February1st to 15thDay
24%26%30%15%2
146
16th to endDay
19%22%33%21%2
239
March1st to 15thDay
27%18%31%17%4
270
16th to endDay
22%18%35%16%5%2
288
April1st to 15thDay
28%15%28%17%8%
270
16th to endDay
21%15%30%18%10%4
270
May1st to 15thDay
36%13%24%14%9%2
288
16th to endDay
18%9%29%27%11%4
331
June1st to 15thDay
23%9%25%23%15%1
315
16th to endDay
14%12%27%26%15%2
315
July1st to 15thDay
15%6%29%29%15%3
305
16th to endDay
15%5%23%30%20%4
326
August1st to 15thDay
16%5%19%32%18%7%
297
16th to endDay
13%417%27%22%13%
268
September1st to 15thDay
15%8%22%23%18%12%
255
16th to endDay
15%9%24%18%15%16%
254
October1st to 15thDay
25%5%22%23%17%4
255
16th to endDay
18%17%28%24%9%
253
November1st to 15thDay
22%10%24%28%11%2
235
16th to endDay
20%20%26%23%6%2
177
December1st to 15thDay
16%33%21%25%3
60
16th to endDay
37%26%26%9%
64
January1st to 15thNight
21%18%34%21%4
720
16th to endNight
21%17%36%22%2
768
February1st to 15thNight
20%17%37%23%1
704
16th to endNight
21%19%36%20%2
631
March1st to 15thNight
23%21%30%21%2
720
16th to endNight
20%21%31%17%7%
768
April1st to 15thNight
24%17%33%20%3
718
16th to endNight
21%16%30%23%7%
681
May1st to 15thNight
21%15%33%23%5%
490
16th to endNight
21%5%28%34%9%
375
June1st to 15thNight
20%5%27%30%14%
360
16th to endNight
13%327%42%13%
360
July1st to 15thNight
15%322%39%17%
340
16th to endNight
13%320%40%21%1
376
August1st to 15thNight
15%121%43%16%1
500
16th to endNight
16%217%36%24%3
700
September1st to 15thNight
17%425%34%14%2
660
16th to endNight
17%5%24%28%20%3
657
October1st to 15thNight
20%9%26%29%12%1
660
16th to endNight
25%11%28%28%5%
704
November1st to 15thNight
21%12%29%27%9%1
700
16th to endNight
21%15%29%23%8%1
720
December1st to 15thNight
24%14%30%24%6%
720
16th to endNight
27%15%35%19%2
768
Page generated at 2017-08-13 14:16:23. Version ac04

Copyright 2017 A. Danko


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