Theodore Roosevelt Nature Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Theodore Roosevelt Nature Center 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
33%
14903
19%
46479
10%
14872
43%
14872
20%
30078

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
20%
720
20%
2506
9%
716
35%
716
15%
1596
January16th to endNight
16%
768
20%
2611
6%
768
34%
768
16%
1646
February1st to 15thNight
16%
704
17%
2198
4%
701
31%
701
17%
1455
February16th to endNight
20%
631
25%
1893
9%
631
41%
631
20%
1193
March1st to 15thNight
22%
720
19%
2160
8%
720
35%
720
20%
1421
March16th to endNight
24%
768
23%
1995
8%
768
36%
768
24%
1343
April1st to 15thNight
29%
718
17%
1796
6%
718
35%
718
23%
1247
April16th to endNight
33%
690
18%
1770
6%
690
39%
690
22%
1227
May1st to 15thNight
33%
537
17%
1617
7%
537
42%
537
17%
1125
May16th to endNight
42%
374
15%
1497
14%
374
49%
374
14%
974
June1st to 15thNight
42%
360
14%
1440
16%
360
48%
360
16%
919
June16th to endNight
55%
360
15%
1440
16%
360
62%
360
21%
851
July1st to 15thNight
54%
340
12%
1360
15%
340
56%
340
19%
837
July16th to endNight
53%
376
16%
1418
16%
354
62%
354
20%
830
August1st to 15thNight
57%
548
19%
1597
13%
546
59%
546
30%
971
August16th to endNight
61%
700
17%
1750
10%
700
63%
700
30%
1158
September1st to 15thNight
52%
660
23%
1657
14%
660
55%
660
31%
1109
September16th to endNight
49%
657
24%
1815
15%
657
56%
657
28%
1158
October1st to 15thNight
38%
660
21%
1905
15%
660
45%
660
24%
1243
October16th to endNight
30%
704
19%
2214
9%
704
43%
704
21%
1409
November1st to 15thNight
28%
700
21%
2277
12%
700
41%
700
21%
1409
November16th to endNight
25%
720
18%
2355
9%
720
37%
720
18%
1512
December1st to 15thNight
20%
720
14%
2520
6%
720
31%
720
13%
1684
December16th to endNight
15%
768
18%
2688
5%
768
32%
768
13%
1761

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%5%2442445%7%42%
47503
Night
16%6%25%424447%41%
46649
Cloud CoverDay
15%5%2442445%7%42%
47513
Night
16%6%25%42445%7%41%
46654
TransparencyDay
39%6%13%23%15%1
47191
Night
42%5%12%22%15%2
46479
SeeingDay
17%12%19%28%17%3
5698
Night
17%20%23%24%12%1
14904

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
15%6%25%5%3435%6%41%
1432
16th to endDay
15%7%245%2335%8%41%
1611
February1st to 15thDay
16%6%345%24447%40%
1663
16th to endDay
15%5%25%6%34447%41%
1580
March1st to 15thDay
17%5%25%5%24448%39%
1790
16th to endDay
17%6%24323346%43%
2226
April1st to 15thDay
18%5%2432335%7%42%
2152
16th to endDay
16%5%24424447%43%
2190
May1st to 15thDay
19%6%235%2445%7%37%
2343
16th to endDay
17%42442446%8%38%
2618
June1st to 15thDay
19%5%2342435%9%38%
2520
16th to endDay
9%4244345%6%9%44%
2520
July1st to 15thDay
8%4245%35%5%6%9%42%
2520
16th to endDay
10%424425%6%7%9%42%
2654
August1st to 15thDay
9%41442446%9%47%
2254
16th to endDay
11%4234345%6%6%48%
2100
September1st to 15thDay
12%5%2442336%6%48%
1972
16th to endDay
14%5%2432335%7%45%
1815
October1st to 15thDay
17%5%24433346%44%
1724
16th to endDay
16%42342335%8%45%
1658
November1st to 15thDay
18%5%24324335%46%
1581
16th to endDay
14%6%24423448%43%
1604
December1st to 15thDay
17%7%243235%5%7%39%
1440
16th to endDay
22%7%24323347%37%
1536
January1st to 15thNight
18%5%25%423346%41%
2506
16th to endNight
17%8%24324447%42%
2611
February1st to 15thNight
15%8%35%424447%39%
2197
16th to endNight
17%5%23424347%45%
1893
March1st to 15thNight
18%6%25%423346%43%
2147
16th to endNight
17%7%24323345%44%
1995
April1st to 15thNight
17%6%25%434447%39%
1796
16th to endNight
18%7%25%324446%40%
1770
May1st to 15thNight
18%9%245%345%5%5%36%
1617
16th to endNight
20%5%1442347%7%36%
1495
June1st to 15thNight
20%425%42445%7%38%
1440
16th to endNight
10%325%5%26%5%6%8%43%
1440
July1st to 15thNight
10%5%25%6%446%6%9%38%
1440
16th to endNight
8%6%25%5%36%46%10%41%
1514
August1st to 15thNight
8%5%15%425%5%6%9%45%
1607
16th to endNight
12%4245%346%49%42%
1750
September1st to 15thNight
14%4144345%5%6%45%
1657
16th to endNight
14%425%423346%47%
1815
October1st to 15thNight
17%7%25%323235%44%
1905
16th to endNight
19%424423445%44%
2214
November1st to 15thNight
17%5%25%423325%47%
2277
16th to endNight
17%6%2442435%7%40%
2355
December1st to 15thNight
20%6%2442345%7%36%
2520
16th to endNight
19%6%25%42445%6%38%
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
15%6%35%5%3435%6%40%
1432
16th to endDay
15%6%3442345%8%41%
1611
February1st to 15thDay
15%6%345%24448%40%
1663
16th to endDay
15%5%25%5%34446%42%
1580
March1st to 15thDay
17%6%24424349%39%
1800
16th to endDay
18%6%34323345%44%
2226
April1st to 15thDay
18%5%24413347%42%
2152
16th to endDay
16%5%24424447%44%
2190
May1st to 15thDay
19%6%2342445%7%37%
2343
16th to endDay
17%5%1443446%9%38%
2618
June1st to 15thDay
19%5%2333435%8%39%
2520
16th to endDay
9%4244445%6%9%44%
2520
July1st to 15thDay
8%4246%35%5%6%9%43%
2520
16th to endDay
10%5%33425%5%7%8%42%
2654
August1st to 15thDay
9%42433446%9%47%
2254
16th to endDay
11%42442445%7%48%
2100
September1st to 15thDay
12%5%2432436%6%48%
1972
16th to endDay
14%5%24323347%46%
1815
October1st to 15thDay
16%6%24433246%44%
1724
16th to endDay
17%31442335%7%45%
1658
November1st to 15thDay
18%424324335%46%
1581
16th to endDay
13%6%2442345%8%43%
1604
December1st to 15thDay
16%7%244235%6%6%39%
1440
16th to endDay
22%7%34314346%37%
1536
January1st to 15thNight
18%5%25%324347%41%
2506
16th to endNight
18%8%14323446%41%
2611
February1st to 15thNight
14%7%35%425%446%39%
2190
16th to endNight
17%5%24424347%44%
1893
March1st to 15thNight
18%6%25%423346%42%
2160
16th to endNight
17%7%24323345%45%
1994
April1st to 15thNight
17%6%25%4245%47%39%
1796
16th to endNight
17%7%34423446%40%
1770
May1st to 15thNight
18%8%34435%45%6%36%
1617
16th to endNight
19%5%244235%7%7%36%
1495
June1st to 15thNight
20%5%15%42435%7%38%
1440
16th to endNight
9%425%5%25%5%6%9%43%
1440
July1st to 15thNight
10%5%247%446%6%9%38%
1440
16th to endNight
8%5%25%5%36%5%6%8%41%
1514
August1st to 15thNight
9%425%4345%6%9%44%
1607
16th to endNight
12%415%5%245%5%8%42%
1750
September1st to 15thNight
14%4244345%45%46%
1657
16th to endNight
14%425%5%23345%48%
1815
October1st to 15thNight
18%6%24323335%45%
1905
16th to endNight
19%424423345%44%
2214
November1st to 15thNight
17%5%25%423235%47%
2277
16th to endNight
17%6%2442435%7%40%
2355
December1st to 15thNight
20%6%35%42345%7%36%
2520
16th to endNight
20%6%25%42445%6%38%
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
43%5%13%24%10%2
1433
16th to endDay
41%316%24%11%2
1611
February1st to 15thDay
43%5%15%20%14%
1666
16th to endDay
42%412%26%12%1
1580
March1st to 15thDay
42%5%16%23%10%2
1800
16th to endDay
41%412%21%17%2
2226
April1st to 15thDay
40%5%10%24%15%3
2152
16th to endDay
39%5%9%22%20%2
2190
May1st to 15thDay
45%5%10%20%16%1
2343
16th to endDay
41%7%15%20%12%1
2622
June1st to 15thDay
42%7%12%23%12%
2520
16th to endDay
34%8%14%25%15%1
2520
July1st to 15thDay
34%9%13%23%17%1
2371
16th to endDay
34%8%14%26%13%2
2487
August1st to 15thDay
31%8%15%26%16%1
2240
16th to endDay
33%7%11%24%20%2
2100
September1st to 15thDay
34%6%14%21%21%1
1972
16th to endDay
37%411%21%22%1
1815
October1st to 15thDay
41%412%22%17%1
1724
16th to endDay
37%5%13%24%16%2
1658
November1st to 15thDay
41%413%20%18%1
1581
16th to endDay
40%5%16%23%12%2
1604
December1st to 15thDay
43%6%17%18%12%
1440
16th to endDay
48%5%15%19%11%
1536
January1st to 15thNight
43%413%22%12%2
2506
16th to endNight
43%312%24%14%1
2611
February1st to 15thNight
44%6%13%21%12%1
2198
16th to endNight
40%410%24%17%2
1893
March1st to 15thNight
43%412%21%13%3
2160
16th to endNight
41%5%8%22%17%5%
1995
April1st to 15thNight
43%5%10%20%16%3
1796
16th to endNight
44%5%8%16%22%2
1770
May1st to 15thNight
47%6%10%17%14%3
1617
16th to endNight
43%9%12%18%14%1
1497
June1st to 15thNight
45%5%12%18%16%
1440
16th to endNight
35%8%12%26%14%1
1440
July1st to 15thNight
39%8%13%23%13%1
1360
16th to endNight
37%8%13%26%11%2
1418
August1st to 15thNight
33%7%15%24%17%2
1597
16th to endNight
36%7%13%23%17%1
1750
September1st to 15thNight
38%5%11%24%19%
1657
16th to endNight
38%47%21%25%1
1815
October1st to 15thNight
42%411%22%16%2
1905
16th to endNight
42%413%23%15%1
2214
November1st to 15thNight
41%311%20%18%3
2277
16th to endNight
44%413%24%11%1
2355
December1st to 15thNight
47%6%16%18%10%
2520
16th to endNight
46%5%15%21%10%1
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
15%15%38%26%5%
60
16th to endDay
22%6%35%33%2
77
February1st to 15thDay
22%20%32%23%1
179
16th to endDay
15%19%33%25%5%
239
March1st to 15thDay
21%18%28%23%6%
270
16th to endDay
19%18%31%23%5%1
288
April1st to 15thDay
18%17%23%30%8%
270
16th to endDay
21%12%19%34%10%2
270
May1st to 15thDay
28%11%23%23%11%1
288
16th to endDay
21%12%10%31%21%3
331
June1st to 15thDay
20%10%16%26%23%3
315
16th to endDay
11%9%15%40%21%1
315
July1st to 15thDay
10%7%10%39%28%4
305
16th to endDay
10%11%9%33%31%4
326
August1st to 15thDay
12%6%8%34%33%6%
297
16th to endDay
12%7%6%29%32%11%
268
September1st to 15thDay
15%6%17%25%25%9%
255
16th to endDay
18%8%13%28%21%9%
254
October1st to 15thDay
24%8%14%25%22%4
255
16th to endDay
14%15%32%24%13%
253
November1st to 15thDay
19%16%22%22%16%2
235
16th to endDay
16%23%26%24%8%1
224
December1st to 15thDay
15%15%31%28%10%
60
16th to endDay
37%7%32%20%1
64
January1st to 15thNight
15%31%29%20%3
720
16th to endNight
19%27%33%17%1
768
February1st to 15thNight
15%26%37%18%1
704
16th to endNight
17%26%31%20%3
631
March1st to 15thNight
20%23%28%21%5%
720
16th to endNight
18%22%30%19%7%1
768
April1st to 15thNight
18%20%26%26%6%
718
16th to endNight
18%18%23%28%10%1
690
May1st to 15thNight
19%20%21%26%11%1
537
16th to endNight
19%17%11%32%16%3
375
June1st to 15thNight
19%17%13%27%20%1
360
16th to endNight
8%17%11%39%22%1
360
July1st to 15thNight
10%12%11%35%28%2
340
16th to endNight
10%17%10%32%25%4
376
August1st to 15thNight
10%9%12%36%27%2
548
16th to endNight
13%10%6%30%31%8%
700
September1st to 15thNight
15%10%16%29%22%5%
660
16th to endNight
16%10%14%28%22%7%
657
October1st to 15thNight
20%14%19%23%19%1
660
16th to endNight
19%17%26%25%9%
704
November1st to 15thNight
17%23%25%17%13%1
700
16th to endNight
16%26%25%21%8%
720
December1st to 15thNight
23%27%24%16%6%1
720
16th to endNight
22%28%30%15%2
768
Page generated at 2017-08-13 14:16:13. Version ac04

Copyright 2017 A. Danko


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