Irving Nature Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Irving Nature Park clear sky chart from 2005-11-06 to 2024-01-13.

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
25%
23309
10%
74781
4%
23249
31%
23249
9%
60213

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 10thNight
16%
850
7%
2838
1%
847
23%
847
5%
2336
January11th to 20thNight
14%
738
6%
2566
1%
738
21%
738
6%
2177
January21st to endNight
16%
792
12%
2574
3%
792
27%
792
9%
2016
February1st to 10thNight
15%
720
9%
2340
2%
720
23%
720
8%
1862
February11th to 20thNight
15%
703
8%
2276
1%
700
25%
700
6%
1856
February21st to endNight
20%
592
12%
1823
3%
592
30%
592
10%
1453
March1st to 10thNight
17%
720
11%
2048
2%
720
27%
720
9%
1675
March11th to 20thNight
22%
720
9%
1980
3%
720
27%
720
9%
1633
March21st to endNight
24%
792
14%
2178
4%
792
33%
792
12%
1724
April1st to 10thNight
20%
630
9%
1872
4%
630
24%
630
9%
1566
April11th to 20thNight
24%
534
13%
1598
6%
534
30%
534
11%
1255
April21st to endNight
24%
540
11%
1620
4%
540
30%
540
10%
1312
May1st to 10thNight
28%
540
9%
1620
5%
540
33%
540
10%
1314
May11th to 20thNight
29%
532
10%
1473
5%
532
34%
532
11%
1214
May21st to endNight
28%
583
8%
1551
5%
582
32%
582
11%
1295
June1st to 10thNight
32%
366
6%
1266
4%
366
34%
366
7%
1071
June11th to 20thNight
34%
360
9%
1260
8%
360
37%
360
9%
1018
June21st to endNight
36%
360
4%
1260
5%
360
37%
360
5%
1105
July1st to 10thNight
37%
350
4%
1225
4%
350
38%
350
6%
1028
July11th to 20thNight
36%
348
7%
1225
5%
348
39%
348
7%
1026
July21st to endNight
37%
559
5%
1642
5%
528
37%
528
8%
1384
August1st to 10thNight
48%
538
6%
1600
6%
534
48%
534
11%
1303
August11th to 20thNight
40%
532
9%
1596
6%
532
42%
532
10%
1321
August21st to endNight
44%
594
12%
1788
7%
594
47%
594
12%
1401
September1st to 10thNight
40%
552
10%
1812
6%
552
44%
552
12%
1384
September11th to 20thNight
41%
720
14%
1980
8%
720
46%
720
14%
1530
September21st to endNight
36%
720
15%
1980
9%
720
40%
720
15%
1554
October1st to 10thNight
37%
720
15%
2137
7%
720
44%
720
15%
1617
October11th to 20thNight
30%
720
13%
2160
5%
720
38%
720
12%
1661
October21st to endNight
22%
792
11%
2456
4%
792
29%
792
9%
1968
November1st to 10thNight
26%
769
9%
2468
5%
769
31%
769
10%
1941
November11th to 20thNight
24%
850
14%
2660
7%
850
33%
850
10%
2116
November21st to endNight
20%
850
9%
2660
3%
850
27%
850
8%
2126
December1st to 10thNight
12%
850
8%
2660
1%
850
19%
850
6%
2237
December11th to 20thNight
12%
850
9%
3410
2%
849
20%
849
5%
2870
December21st to endNight
12%
923
5%
5179
1%
906
19%
906
3%
3864

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
21%8%36%5%3445%7%34%
74671
Night
22%9%36%5%3445%6%33%
75058
TransparencyDay
35%36%7%14%7%1
74376
Night
36%35%7%14%7%1
74888
SeeingDay
26%13%29%23%8%1
15324
Night
27%13%28%23%8%1
23321

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 10thDay
15%13%47%5%3445%8%32%
1327
11th to 20thDay
23%13%47%5%33435%31%
1436
21st to endDay
14%9%35%6%35%5%5%8%38%
1782
February1st to 10thDay
18%12%35%5%445%6%7%31%
1620
11th to 20thDay
16%11%36%6%45%45%8%31%
1573
21st to endDay
12%10%47%5%345%5%8%36%
1430
March1st to 10thDay
16%9%48%6%46%5%5%6%32%
1908
11th to 20thDay
17%8%35%6%45%5%5%7%35%
1980
21st to endDay
18%10%36%5%44446%37%
2178
April1st to 10thDay
23%10%46%5%4446%6%29%
2085
11th to 20thDay
21%8%35%5%33447%37%
2312
21st to endDay
25%7%37%5%3445%7%31%
2340
May1st to 10thDay
23%9%46%5%345%6%6%28%
2340
11th to 20thDay
24%6%3442445%5%38%
2419
21st to endDay
24%8%35%5%345%5%8%30%
2732
June1st to 10thDay
25%8%36%5%46%45%6%28%
2700
11th to 20thDay
23%7%37%434446%35%
2700
21st to endDay
30%7%35%5%34447%29%
2700
July1st to 10thDay
21%7%35%5%35%5%6%8%33%
2700
11th to 20thDay
22%8%35%4345%6%8%33%
2690
21st to endDay
21%9%35%5%346%7%7%31%
2558
August1st to 10thDay
18%8%26%6%3446%8%35%
2327
11th to 20thDay
21%7%35%5%35%47%8%32%
2304
21st to endDay
17%6%25%5%2445%7%43%
2566
September1st to 10thDay
17%6%244245%6%7%43%
2145
11th to 20thDay
20%6%23323446%46%
1980
21st to endDay
22%42442335%6%45%
1980
October1st to 10thDay
18%6%25%5%3445%6%41%
1823
11th to 20thDay
20%7%25%5%3445%5%40%
1800
21st to endDay
21%8%36%5%3445%6%34%
1900
November1st to 10thDay
24%7%26%5%24447%35%
1610
11th to 20thDay
20%5%25%5%3347%6%39%
1520
21st to endDay
23%8%36%5%245%48%32%
1520
December1st to 10thDay
26%9%35%4345%5%7%29%
1520
11th to 20thDay
25%13%47%6%24436%28%
1735
21st to endDay
24%9%3442445%7%34%
2431
January1st to 10thNight
18%12%37%5%46%45%7%30%
2838
11th to 20thNight
21%12%47%5%35%45%7%28%
2566
21st to endNight
14%10%37%6%345%6%9%33%
2574
February1st to 10thNight
19%10%35%5%345%6%8%31%
2340
11th to 20thNight
18%12%46%5%45%6%5%6%30%
2273
21st to endNight
15%10%48%5%36%6%5%5%34%
1823
March1st to 10thNight
16%10%37%5%35%5%5%5%34%
2039
11th to 20thNight
19%10%46%6%35%5%5%6%32%
1979
21st to endNight
18%9%46%43445%6%37%
2178
April1st to 10thNight
24%11%36%5%4444430%
1872
11th to 20thNight
24%7%345%3445%7%34%
1598
21st to endNight
27%8%26%5%2445%6%30%
1620
May1st to 10thNight
24%9%36%5%345%5%7%29%
1620
11th to 20thNight
28%6%35%5%35%5%46%31%
1472
21st to endNight
23%9%47%6%34437%31%
1550
June1st to 10thNight
29%11%35%5%3435%8%23%
1266
11th to 20thNight
24%7%46%5%34447%32%
1260
21st to endNight
33%9%35%5%34345%26%
1260
July1st to 10thNight
25%9%47%435%5%5%6%27%
1260
11th to 20thNight
25%11%5%6%4345%47%26%
1267
21st to endNight
26%11%35%6%35%5%47%24%
1739
August1st to 10thNight
18%9%36%4345%5%8%33%
1612
11th to 20thNight
25%11%36%5%2446%6%28%
1596
21st to endNight
18%7%35%5%2445%8%39%
1788
September1st to 10thNight
20%7%25%43345%7%40%
1812
11th to 20thNight
21%7%3432335%7%43%
1980
21st to endNight
22%7%24423346%42%
1980
October1st to 10thNight
22%6%2443445%7%41%
2137
11th to 20thNight
20%7%25%5%3445%6%40%
2160
21st to endNight
24%9%35%6%24346%34%
2456
November1st to 10thNight
23%6%25%5%3445%5%38%
2468
11th to 20thNight
21%7%36%5%345%5%6%36%
2660
21st to endNight
21%8%25%5%345%5%7%34%
2660
December1st to 10thNight
28%11%46%43345%5%27%
2660
11th to 20thNight
29%9%35%5%34446%28%
3459
21st to endNight
23%10%36%5%34446%32%
5236

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 10thDay
35%39%8%12%5%1
1328
11th to 20thDay
37%41%7%11%41
1436
21st to endDay
30%36%7%17%10%
1782
February1st to 10thDay
35%36%8%13%7%1
1620
11th to 20thDay
35%36%10%12%6%1
1581
21st to endDay
33%35%7%16%7%2
1430
March1st to 10thDay
37%35%6%14%8%1
1912
11th to 20thDay
33%35%8%14%9%1
1980
21st to endDay
33%35%5%16%9%2
2178
April1st to 10thDay
38%35%7%10%10%1
2085
11th to 20thDay
31%34%6%16%11%1
2312
21st to endDay
35%35%6%13%9%2
2340
May1st to 10thDay
40%35%411%8%2
2340
11th to 20thDay
33%35%6%17%9%1
2423
21st to endDay
34%36%8%14%6%1
2732
June1st to 10thDay
40%35%7%12%5%1
2700
11th to 20thDay
36%35%6%13%7%2
2700
21st to endDay
44%36%6%9%41
2700
July1st to 10thDay
36%37%11%11%5%
2625
11th to 20thDay
37%37%9%12%5%
2609
21st to endDay
36%38%8%15%4
2415
August1st to 10thDay
37%36%7%14%6%
2314
11th to 20thDay
35%35%7%17%6%
2304
21st to endDay
29%36%8%18%9%1
2566
September1st to 10thDay
30%35%8%17%10%1
2145
11th to 20thDay
27%35%7%17%11%3
1980
21st to endDay
31%35%5%18%10%
1980
October1st to 10thDay
30%35%7%19%8%
1823
11th to 20thDay
31%36%7%20%6%
1800
21st to endDay
32%36%8%15%10%
1900
November1st to 10thDay
31%39%6%14%9%
1610
11th to 20thDay
26%39%8%15%11%1
1520
21st to endDay
35%39%7%14%5%
1520
December1st to 10thDay
36%40%7%13%41
1520
11th to 20thDay
46%31%6%11%6%
1735
21st to endDay
41%23%12%15%7%1
2431
January1st to 10thNight
37%39%7%13%5%
2838
11th to 20thNight
36%42%7%11%41
2566
21st to endNight
32%37%7%16%8%1
2574
February1st to 10thNight
34%35%9%13%7%1
2340
11th to 20thNight
38%36%8%11%6%2
2276
21st to endNight
35%35%7%15%7%1
1823
March1st to 10thNight
37%35%7%11%9%1
2048
11th to 20thNight
37%36%8%11%6%2
1980
21st to endNight
32%35%5%15%11%2
2178
April1st to 10thNight
40%35%5%10%8%2
1872
11th to 20thNight
34%34%6%14%11%1
1598
21st to endNight
36%35%5%14%8%2
1620
May1st to 10thNight
37%35%6%12%9%1
1620
11th to 20thNight
37%36%6%14%7%1
1473
21st to endNight
37%36%5%14%6%1
1551
June1st to 10thNight
42%36%6%12%31
1266
11th to 20thNight
38%35%7%13%5%1
1260
21st to endNight
47%36%49%31
1260
July1st to 10thNight
41%38%9%8%5%
1225
11th to 20thNight
41%36%6%11%5%
1225
21st to endNight
39%38%7%10%5%
1642
August1st to 10thNight
37%35%7%16%5%
1600
11th to 20thNight
40%34%6%16%4
1596
21st to endNight
33%36%6%16%9%
1788
September1st to 10thNight
32%34%6%17%9%1
1812
11th to 20thNight
30%34%5%16%13%1
1980
21st to endNight
32%34%5%18%10%1
1980
October1st to 10thNight
29%34%6%21%9%
2137
11th to 20thNight
31%35%8%18%8%1
2160
21st to endNight
35%36%6%14%9%1
2456
November1st to 10thNight
29%40%8%14%9%
2468
11th to 20thNight
32%39%7%13%9%1
2660
21st to endNight
31%40%9%14%6%1
2660
December1st to 10thNight
38%38%7%12%5%
2660
11th to 20thNight
45%32%5%13%5%
3460
21st to endNight
46%24%9%14%34
5236

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 10thDay
28%21%28%22%2
180
11th to 20thDay
32%20%32%13%21
164
21st to endDay
20%19%39%20%21
374
February1st to 10thDay
26%20%34%16%3
340
11th to 20thDay
24%25%32%15%3
336
21st to endDay
17%23%37%20%3
324
March1st to 10thDay
21%20%36%20%2
420
11th to 20thDay
20%20%36%19%5%
420
21st to endDay
26%16%34%16%7%1
462
April1st to 10thDay
33%20%28%15%31
420
11th to 20thDay
24%17%34%18%5%1
412
21st to endDay
27%15%29%19%8%2
420
May1st to 10thDay
25%15%34%20%5%1
423
11th to 20thDay
27%10%31%22%8%1
565
21st to endDay
30%11%28%21%8%2
680
June1st to 10thDay
29%9%29%23%10%1
630
11th to 20thDay
27%8%27%25%11%1
630
21st to endDay
33%5%25%25%10%2
630
July1st to 10thDay
27%7%28%28%10%1
620
11th to 20thDay
28%7%20%29%13%2
608
21st to endDay
26%8%28%28%9%1
488
August1st to 10thDay
20%6%25%34%13%1
446
11th to 20thDay
28%5%21%34%10%2
439
21st to endDay
22%9%22%29%15%2
495
September1st to 10thDay
20%6%27%34%12%1
450
11th to 20thDay
25%9%26%25%11%3
450
21st to endDay
22%8%31%26%11%2
450
October1st to 10thDay
23%12%24%25%13%3
372
11th to 20thDay
23%13%27%27%9%2
360
21st to endDay
26%14%33%21%5%2
396
November1st to 10thDay
26%16%28%21%7%2
365
11th to 20thDay
25%18%32%19%6%
370
21st to endDay
29%21%31%16%21
370
December1st to 10thDay
28%19%32%17%4
370
11th to 20thDay
29%28%29%10%4
247
21st to endDay
28%27%26%15%5%1
198
January1st to 10thNight
26%19%32%19%4
850
11th to 20thNight
28%20%33%16%4
738
21st to endNight
20%20%38%16%5%
792
February1st to 10thNight
26%21%34%17%2
720
11th to 20thNight
25%22%33%17%21
703
21st to endNight
22%17%35%21%5%
592
March1st to 10thNight
23%17%37%22%2
720
11th to 20thNight
24%15%33%24%5%
720
21st to endNight
23%14%33%22%7%1
792
April1st to 10thNight
31%13%32%20%4
630
11th to 20thNight
27%9%34%25%5%
534
21st to endNight
30%9%29%24%7%1
540
May1st to 10thNight
29%6%30%27%8%1
540
11th to 20thNight
31%7%27%28%8%1
532
21st to endNight
28%9%28%27%7%1
583
June1st to 10thNight
37%5%19%28%10%
366
11th to 20thNight
27%6%22%31%13%1
360
21st to endNight
39%311%33%13%1
360
July1st to 10thNight
31%5%16%34%13%1
350
11th to 20thNight
31%6%18%28%16%1
348
21st to endNight
29%7%16%33%15%
559
August1st to 10thNight
22%418%39%17%1
538
11th to 20thNight
30%6%14%34%14%2
532
21st to endNight
21%5%21%31%19%2
594
September1st to 10thNight
24%5%24%32%14%2
552
11th to 20thNight
25%7%21%28%17%2
720
21st to endNight
26%7%26%26%14%2
720
October1st to 10thNight
24%7%26%28%13%2
720
11th to 20thNight
23%12%30%22%12%2
720
21st to endNight
29%15%30%21%4
792
November1st to 10thNight
26%12%29%23%9%1
769
11th to 20thNight
25%18%27%22%7%1
850
21st to endNight
26%21%28%19%5%
850
December1st to 10thNight
33%17%32%15%3
850
11th to 20thNight
30%23%32%12%3
850
21st to endNight
30%21%30%16%4
935
Page generated at 2024-01-10 02:24:59. Version ac07

Copyright 2024 Attilla Danko


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