Vincennes
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Vincennes clear sky chart from 2005-11-06 to 2024-12-24.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	13% 8% 3 6% 4 4 4 4 5% 8% 40%	101461
	Night	15% 8% 3 6% 4 4 4 3 5% 7% 41%	98672
Transparency	Day	40% 6% 11% 24% 16% 2	105108
	Night	41% 6% 11% 23% 17% 3	103166
Seeing	Day	15% 8% 24% 25% 19% 9%	15691
	Night	17% 7% 26% 32% 16% 2	25550

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 14% 8% 10% 4 4 4 4 4 5% 30%	2527
	11th to 20th	Day	17% 10% 4 10% 7% 7% 5% 4 5% 5% 27%	2530
	21st to end	Day	26% 17% 5% 8% 4 3 3 2 4 5% 23%	2998
February	1st to 10th	Day	17% 12% 4 8% 5% 4 3 2 5% 6% 33%	1900
	11th to 20th	Day	15% 11% 3 8% 5% 4 4 3 5% 6% 34%	1848
	21st to end	Day	17% 10% 4 9% 5% 4 4 3 4 6% 34%	1570
March	1st to 10th	Day	23% 13% 4 7% 4 3 3 2 3 4 34%	3120
	11th to 20th	Day	14% 7% 2 6% 4 3 3 3 5% 8% 45%	3251
	21st to end	Day	14% 9% 3 7% 6% 5% 5% 4 5% 8% 34%	4155
April	1st to 10th	Day	14% 8% 3 6% 5% 4 4 3 5% 8% 40%	2280
	11th to 20th	Day	16% 8% 2 6% 4 4 4 3 5% 6% 40%	2254
	21st to end	Day	19% 6% 3 6% 5% 4 4 3 5% 7% 39%	2337
May	1st to 10th	Day	17% 7% 3 7% 5% 5% 5% 5% 7% 10% 30%	4082
	11th to 20th	Day	19% 7% 2 6% 5% 4 4 3 5% 7% 38%	4081
	21st to end	Day	10% 6% 3 7% 5% 5% 5% 5% 6% 9% 40%	4663
June	1st to 10th	Day	10% 6% 3 5% 4 4 4 4 7% 7% 46%	2660
	11th to 20th	Day	7% 5% 2 5% 5% 5% 4 4 7% 8% 48%	2660
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 7% 9% 44%	2660
July	1st to 10th	Day	13% 6% 2 5% 5% 4 5% 4 6% 10% 41%	4440
	11th to 20th	Day	6% 4 2 5% 4 4 5% 5% 6% 12% 47%	4440
	21st to end	Day	10% 7% 3 8% 5% 6% 7% 6% 8% 10% 31%	4764
August	1st to 10th	Day	8% 4 1 4 3 3 4 4 6% 11% 51%	3983
	11th to 20th	Day	8% 5% 2 6% 5% 4 6% 5% 7% 10% 42%	3729
	21st to end	Day	5% 5% 2 5% 3 4 5% 4 6% 9% 54%	4180
September	1st to 10th	Day	11% 5% 2 6% 4 3 5% 4 5% 7% 48%	2280
	11th to 20th	Day	9% 4 2 6% 4 4 4 3 6% 8% 50%	2116
	21st to end	Day	12% 4 2 4 3 3 3 3 5% 7% 53%	2090
October	1st to 10th	Day	11% 5% 2 4 3 3 3 2 5% 6% 56%	2090
	11th to 20th	Day	13% 6% 2 5% 4 3 4 3 4 6% 49%	1938
	21st to end	Day	18% 7% 3 6% 4 4 3 2 4 5% 44%	1893
November	1st to 10th	Day	9% 5% 2 6% 4 3 3 3 5% 7% 53%	1762
	11th to 20th	Day	16% 8% 2 7% 4 3 3 3 4 6% 43%	1800
	21st to end	Day	19% 11% 3 7% 4 3 3 3 4 6% 39%	1800
December	1st to 10th	Day	17% 13% 4 7% 5% 4 3 2 4 5% 36%	1775
	11th to 20th	Day	17% 12% 6% 10% 4 4 4 4 5% 5% 30%	1998
	21st to end	Day	23% 17% 6% 9% 5% 4 4 3 4 5% 21%	2807
January	1st to 10th	Night	18% 12% 5% 7% 4 4 4 4 5% 6% 30%	4428
	11th to 20th	Night	16% 14% 5% 11% 4 6% 6% 3 4 4 27%	4440
	21st to end	Night	25% 15% 6% 7% 4 3 3 3 4 5% 26%	4649
February	1st to 10th	Night	20% 11% 4 8% 5% 4 4 4 5% 5% 30%	2280
	11th to 20th	Night	15% 10% 3 7% 5% 5% 4 3 4 7% 37%	2218
	21st to end	Night	20% 10% 3 7% 5% 4 3 3 4 5% 34%	1884
March	1st to 10th	Night	23% 12% 3 8% 4 3 3 3 4 5% 33%	3733
	11th to 20th	Night	12% 6% 2 6% 4 3 3 3 4 6% 50%	3707
	21st to end	Night	18% 8% 3 6% 5% 4 5% 4 5% 5% 38%	3505
April	1st to 10th	Night	12% 7% 2 7% 5% 4 4 4 5% 6% 43%	1900
	11th to 20th	Night	16% 7% 2 5% 4 3 4 3 6% 7% 44%	1875
	21st to end	Night	18% 7% 2 5% 5% 4 4 5% 6% 7% 37%	1842
May	1st to 10th	Night	16% 8% 3 7% 5% 5% 4 4 6% 9% 33%	2813
	11th to 20th	Night	17% 7% 2 6% 4 4 4 3 5% 6% 43%	2812
	21st to end	Night	10% 6% 2 6% 5% 5% 6% 5% 7% 9% 40%	2881
June	1st to 10th	Night	9% 7% 2 4 3 4 4 3 7% 9% 48%	1520
	11th to 20th	Night	8% 5% 1 4 4 4 5% 4 6% 9% 50%	1520
	21st to end	Night	6% 3 1 4 3 5% 6% 4 8% 9% 51%	1520
July	1st to 10th	Night	11% 6% 2 5% 4 4 4 4 5% 9% 47%	2530
	11th to 20th	Night	5% 3 1 4 3 4 5% 4 6% 7% 56%	2530
	21st to end	Night	9% 7% 3 8% 6% 6% 5% 5% 7% 10% 35%	2796
August	1st to 10th	Night	5% 4 1 5% 4 4 3 3 6% 8% 57%	2942
	11th to 20th	Night	6% 4 2 5% 4 4 5% 4 6% 8% 51%	3100
	21st to end	Night	3 3 2 5% 3 4 4 4 6% 9% 58%	3476
September	1st to 10th	Night	10% 6% 2 5% 3 4 3 3 4 6% 53%	1900
	11th to 20th	Night	7% 4 2 5% 4 4 4 4 5% 7% 54%	2043
	21st to end	Night	12% 5% 2 5% 3 3 3 3 5% 8% 50%	2090
October	1st to 10th	Night	9% 4 1 5% 2 3 3 3 5% 6% 59%	2090
	11th to 20th	Night	15% 5% 2 5% 3 3 3 2 4 5% 52%	2237
	21st to end	Night	18% 7% 2 6% 3 4 4 2 5% 5% 44%	2703
November	1st to 10th	Night	12% 7% 2 5% 3 3 3 2 5% 6% 52%	2536
	11th to 20th	Night	14% 7% 2 5% 4 3 4 3 4 6% 47%	2600
	21st to end	Night	20% 9% 3 5% 4 3 3 3 4 6% 41%	2600
December	1st to 10th	Night	19% 9% 3 7% 4 3 4 3 4 7% 36%	2620
	11th to 20th	Night	19% 10% 3 8% 3 3 4 3 4 5% 38%	3419
	21st to end	Night	24% 16% 5% 8% 5% 4 4 3 4 4 23%	4933

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	54% 5% 11% 21% 8%	2528
	11th to 20th	Day	58% 8% 11% 18% 5%	2530
	21st to end	Day	64% 4 8% 18% 4 1	2998
February	1st to 10th	Day	53% 4 10% 21% 10% 2	1900
	11th to 20th	Day	51% 4 10% 22% 12% 2	1858
	21st to end	Day	52% 5% 8% 21% 11% 3	1570
March	1st to 10th	Day	55% 3 6% 19% 13% 4	3120
	11th to 20th	Day	38% 6% 11% 28% 15% 2	3251
	21st to end	Day	45% 9% 13% 23% 10% 1	4155
April	1st to 10th	Day	42% 7% 12% 23% 15% 1	2280
	11th to 20th	Day	43% 6% 10% 24% 14% 3	2254
	21st to end	Day	45% 5% 11% 24% 12% 3	2337
May	1st to 10th	Day	45% 11% 14% 22% 8%	4120
	11th to 20th	Day	44% 8% 11% 25% 11%	4085
	21st to end	Day	37% 8% 13% 19% 20% 3	4676
June	1st to 10th	Day	33% 9% 13% 25% 17% 4	2660
	11th to 20th	Day	31% 9% 12% 24% 20% 4	2660
	21st to end	Day	35% 8% 15% 21% 16% 5%	2660
July	1st to 10th	Day	37% 7% 11% 26% 16% 2	4371
	11th to 20th	Day	27% 8% 14% 32% 17% 2	4365
	21st to end	Day	43% 10% 16% 21% 9% 1	4614
August	1st to 10th	Day	26% 7% 15% 36% 16% 1	3970
	11th to 20th	Day	34% 7% 16% 25% 17% 1	3765
	21st to end	Day	26% 6% 17% 32% 16% 4	4179
September	1st to 10th	Day	35% 6% 10% 24% 19% 4	2280
	11th to 20th	Day	32% 5% 12% 25% 22% 3	2116
	21st to end	Day	32% 5% 8% 26% 26% 3	2090
October	1st to 10th	Day	19% 3 6% 28% 41% 3	3480
	11th to 20th	Day	25% 4 8% 25% 34% 3	3204
	21st to end	Day	35% 3 8% 24% 28% 2	3093
November	1st to 10th	Day	32% 5% 10% 30% 17% 6%	1762
	11th to 20th	Day	43% 4 9% 23% 18% 5%	1800
	21st to end	Day	49% 3 9% 22% 15% 2	1800
December	1st to 10th	Day	51% 4 11% 22% 11% 1	1775
	11th to 20th	Day	56% 5% 8% 22% 9% 1	1995
	21st to end	Day	65% 5% 11% 12% 6%	2807
January	1st to 10th	Night	52% 7% 12% 20% 8% 1	4428
	11th to 20th	Night	60% 6% 9% 16% 8% 1	4440
	21st to end	Night	61% 4 9% 16% 9% 1	4649
February	1st to 10th	Night	56% 5% 11% 19% 9% 1	2280
	11th to 20th	Night	47% 5% 11% 21% 14% 1	2219
	21st to end	Night	52% 4 10% 20% 11% 3	1884
March	1st to 10th	Night	54% 4 7% 20% 12% 2	3733
	11th to 20th	Night	35% 6% 12% 24% 21% 2	3707
	21st to end	Night	46% 7% 10% 27% 9% 1	3505
April	1st to 10th	Night	40% 6% 10% 27% 15% 3	1900
	11th to 20th	Night	39% 4 11% 22% 19% 4	1875
	21st to end	Night	44% 6% 11% 22% 14% 3	1842
May	1st to 10th	Night	45% 12% 15% 21% 7% 1	2840
	11th to 20th	Night	41% 7% 13% 26% 13% 1	2813
	21st to end	Night	36% 10% 13% 20% 17% 4	2889
June	1st to 10th	Night	32% 6% 10% 26% 22% 4	1520
	11th to 20th	Night	29% 7% 12% 22% 23% 7%	1520
	21st to end	Night	26% 10% 15% 22% 20% 8%	1520
July	1st to 10th	Night	35% 6% 9% 26% 20% 4	2490
	11th to 20th	Night	24% 7% 12% 32% 21% 3	2482
	21st to end	Night	42% 7% 17% 20% 12% 2	2707
August	1st to 10th	Night	24% 7% 15% 39% 14% 2	2931
	11th to 20th	Night	29% 7% 14% 29% 19% 2	3130
	21st to end	Night	23% 6% 14% 29% 24% 4	3476
September	1st to 10th	Night	32% 6% 9% 25% 22% 6%	1900
	11th to 20th	Night	29% 4 11% 24% 27% 5%	2043
	21st to end	Night	33% 6% 10% 22% 23% 6%	2090
October	1st to 10th	Night	17% 4 7% 19% 49% 5%	3480
	11th to 20th	Night	25% 2 6% 27% 36% 4	3710
	21st to end	Night	32% 4 7% 24% 27% 6%	4453
November	1st to 10th	Night	34% 5% 9% 25% 22% 5%	2536
	11th to 20th	Night	38% 4 9% 22% 22% 4	2600
	21st to end	Night	46% 3 11% 23% 15% 2	2600
December	1st to 10th	Night	48% 5% 12% 22% 12% 1	2620
	11th to 20th	Night	48% 5% 11% 22% 13% 1	3421
	21st to end	Night	64% 6% 8% 13% 7% 1	4933

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	23% 14% 32% 22% 7% 1	270
	11th to 20th	Day	27% 16% 31% 21% 5%	270
	21st to end	Day	24% 14% 38% 18% 7%	297
February	1st to 10th	Day	24% 16% 35% 21% 3	270
	11th to 20th	Day	22% 19% 36% 17% 4 1	270
	21st to end	Day	27% 10% 39% 20% 4	225
March	1st to 10th	Day	21% 19% 37% 18% 4 1	270
	11th to 20th	Day	25% 18% 34% 15% 7% 1	322
	21st to end	Day	27% 14% 34% 17% 7% 1	506
April	1st to 10th	Day	17% 16% 32% 26% 9% 1	460
	11th to 20th	Day	20% 14% 28% 22% 14% 2	452
	21st to end	Day	21% 13% 33% 21% 8% 3	460
May	1st to 10th	Day	19% 11% 29% 28% 9% 3	463
	11th to 20th	Day	20% 6% 26% 24% 16% 8%	487
	21st to end	Day	11% 4 26% 26% 20% 13%	638
June	1st to 10th	Day	12% 5% 21% 25% 28% 8%	680
	11th to 20th	Day	10% 4 19% 32% 26% 11%	680
	21st to end	Day	8% 5% 25% 31% 21% 11%	680
July	1st to 10th	Day	11% 3 12% 25% 25% 24%	671
	11th to 20th	Day	7% 2 13% 33% 28% 17%	668
	21st to end	Day	10% 2 12% 29% 34% 13%	714
August	1st to 10th	Day	9% 3 12% 25% 34% 18%	486
	11th to 20th	Day	12% 3 12% 29% 32% 13%	479
	21st to end	Day	7% 1 9% 23% 37% 23%	539
September	1st to 10th	Day	9% 3 14% 25% 33% 15%	490
	11th to 20th	Day	8% 2 10% 27% 36% 16%	490
	21st to end	Day	15% 4 20% 24% 24% 13%	490
October	1st to 10th	Day	11% 4 19% 34% 22% 10%	490
	11th to 20th	Day	12% 11% 33% 26% 13% 5%	338
	21st to end	Day	23% 12% 32% 25% 7% 1	330
November	1st to 10th	Day	13% 8% 35% 23% 14% 6%	300
	11th to 20th	Day	17% 16% 31% 22% 10% 2	300
	21st to end	Day	26% 9% 26% 26% 10% 2	300
December	1st to 10th	Day	15% 19% 36% 18% 8% 3	300
	11th to 20th	Day	23% 13% 35% 20% 8% 1	300
	21st to end	Day	29% 15% 33% 18% 5% 1	306
January	1st to 10th	Night	21% 12% 34% 28% 5%	950
	11th to 20th	Night	25% 13% 36% 23% 4	950
	21st to end	Night	23% 10% 36% 29% 3	1034
February	1st to 10th	Night	26% 10% 35% 26% 3	760
	11th to 20th	Night	21% 13% 38% 27% 2	743
	21st to end	Night	25% 13% 37% 23% 2	628
March	1st to 10th	Night	22% 11% 36% 27% 4	760
	11th to 20th	Night	20% 11% 37% 25% 7% 1	760
	21st to end	Night	24% 8% 29% 32% 6% 1	653
April	1st to 10th	Night	16% 10% 32% 35% 7%	570
	11th to 20th	Night	18% 8% 31% 29% 13% 1	563
	21st to end	Night	21% 6% 32% 31% 8% 1	570
May	1st to 10th	Night	16% 6% 29% 37% 10% 1	570
	11th to 20th	Night	15% 5% 23% 37% 18% 2	561
	21st to end	Night	9% 3 19% 40% 26% 3	617
June	1st to 10th	Night	12% 2 18% 41% 26% 1	570
	11th to 20th	Night	9% 2 17% 44% 26% 2	570
	21st to end	Night	7% 20% 42% 29% 2	570
July	1st to 10th	Night	10% 1 10% 34% 36% 8%	555
	11th to 20th	Night	5% 2 10% 42% 37% 5%	552
	21st to end	Night	8% 1 10% 38% 36% 5%	624
August	1st to 10th	Night	7% 1 8% 41% 38% 5%	567
	11th to 20th	Night	7% 1 9% 40% 39% 4	564
	21st to end	Night	6% 2 7% 34% 42% 9%	627
September	1st to 10th	Night	12% 2 10% 33% 38% 5%	570
	11th to 20th	Night	7% 1 14% 34% 37% 7%	713
	21st to end	Night	13% 4 20% 30% 29% 4	760
October	1st to 10th	Night	10% 4 19% 38% 24% 5%	760
	11th to 20th	Night	18% 6% 29% 29% 16% 2	760
	21st to end	Night	22% 8% 31% 31% 9%	836
November	1st to 10th	Night	13% 7% 31% 34% 14% 1	780
	11th to 20th	Night	17% 10% 32% 31% 9% 1	800
	21st to end	Night	23% 11% 27% 30% 9%	800
December	1st to 10th	Night	24% 8% 34% 27% 6%	820
	11th to 20th	Night	25% 7% 30% 30% 7% 1	1000
	21st to end	Night	28% 13% 32% 23% 4	1063

Page generated at 2024-12-21 04:13:52. Version ac07

Copyright © 2024 Attilla Danko.