Little Rock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Rock clear sky chart from 2005-11-06 to 2024-09-14.

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% 6% 2 6% 4 4 4 4 5% 7% 45%	100065
	Night	13% 5% 2 5% 4 3 3 3 5% 6% 50%	97868
Transparency	Day	37% 6% 10% 24% 19% 4	99872
	Night	34% 5% 10% 23% 22% 6%	97733
Seeing	Day	15% 9% 23% 26% 21% 7%	15181
	Night	15% 7% 25% 32% 19% 2	24921

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	18% 8% 2 6% 4 3 3 2 4 5% 44%	2847
	11th to 20th	Day	13% 10% 3 6% 4 3 3 3 3 4 48%	2850
	21st to end	Day	25% 8% 2 4 3 2 1 2 3 4 46%	3135
February	1st to 10th	Day	21% 8% 3 5% 4 3 3 4 3 6% 41%	1710
	11th to 20th	Day	18% 9% 3 6% 4 3 3 3 4 5% 43%	1803
	21st to end	Day	23% 8% 2 6% 5% 4 4 3 4 4 37%	1606
March	1st to 10th	Day	20% 9% 3 7% 4 4 3 2 4 4 38%	3436
	11th to 20th	Day	14% 6% 3 5% 5% 4 4 3 5% 6% 45%	3480
	21st to end	Day	16% 8% 3 7% 4 4 3 3 4 5% 43%	3832
April	1st to 10th	Day	13% 7% 2 6% 3 4 4 3 5% 7% 46%	2280
	11th to 20th	Day	16% 7% 2 6% 4 4 4 2 4 6% 45%	2254
	21st to end	Day	15% 7% 2 6% 5% 4 4 4 5% 7% 41%	2280
May	1st to 10th	Day	16% 7% 3 7% 5% 4 5% 4 5% 7% 38%	3765
	11th to 20th	Day	11% 5% 2 6% 5% 5% 5% 5% 6% 7% 43%	4004
	21st to end	Day	12% 6% 3 9% 6% 6% 5% 5% 7% 8% 34%	4477
June	1st to 10th	Day	9% 5% 2 5% 5% 5% 5% 5% 8% 8% 43%	2636
	11th to 20th	Day	5% 3 2 5% 5% 5% 5% 5% 6% 10% 48%	2660
	21st to end	Day	4 4 1 5% 4 5% 6% 5% 8% 11% 48%	2515
July	1st to 10th	Day	8% 5% 2 6% 5% 5% 5% 5% 7% 11% 41%	4120
	11th to 20th	Day	6% 4 2 5% 4 4 5% 4 7% 8% 52%	4120
	21st to end	Day	12% 8% 3 8% 6% 6% 5% 5% 6% 9% 33%	4465
August	1st to 10th	Day	3 3 1 4 3 3 4 4 6% 9% 60%	4090
	11th to 20th	Day	8% 5% 2 7% 4 5% 6% 4 7% 9% 42%	3729
	21st to end	Day	5% 3 2 5% 5% 5% 5% 4 7% 8% 50%	4180
September	1st to 10th	Day	11% 5% 2 5% 4 5% 5% 5% 6% 7% 45%	2280
	11th to 20th	Day	14% 5% 2 5% 3 4 5% 4 6% 7% 46%	2197
	21st to end	Day	10% 4 2 5% 4 4 4 3 5% 6% 55%	1890
October	1st to 10th	Day	8% 4 2 4 3 4 4 3 6% 6% 57%	1800
	11th to 20th	Day	16% 4 2 3 2 3 3 2 4 6% 55%	1800
	21st to end	Day	18% 5% 2 4 3 3 3 2 4 5% 52%	1980
November	1st to 10th	Day	11% 6% 2 3 3 3 3 2 4 5% 58%	1858
	11th to 20th	Day	11% 6% 1 4 3 3 3 3 6% 7% 55%	1821
	21st to end	Day	19% 8% 2 5% 4 2 4 3 4 5% 44%	1688
December	1st to 10th	Day	19% 8% 3 4 3 3 3 2 5% 5% 45%	1520
	11th to 20th	Day	15% 8% 4 6% 4 3 3 4 4 4 44%	1918
	21st to end	Day	14% 7% 3 7% 5% 5% 5% 4 6% 6% 38%	3039
January	1st to 10th	Night	17% 7% 3 6% 4 3 3 2 4 5% 46%	4108
	11th to 20th	Night	18% 6% 1 4 3 3 2 2 3 4 53%	4120
	21st to end	Night	25% 6% 2 3 3 2 3 2 3 4 48%	4532
February	1st to 10th	Night	21% 8% 3 5% 3 3 3 3 3 6% 43%	2470
	11th to 20th	Night	18% 8% 3 6% 4 3 3 3 3 5% 46%	2261
	21st to end	Night	21% 6% 2 4 3 3 3 2 4 5% 46%	1863
March	1st to 10th	Night	20% 7% 2 5% 4 3 3 3 5% 5% 41%	3419
	11th to 20th	Night	15% 7% 2 5% 3 3 3 3 4 5% 49%	3480
	21st to end	Night	12% 6% 3 7% 5% 4 4 3 5% 7% 44%	3797
April	1st to 10th	Night	12% 5% 2 4 4 3 3 3 6% 7% 50%	1900
	11th to 20th	Night	12% 5% 2 4 4 3 3 3 5% 7% 51%	1875
	21st to end	Night	13% 6% 3 5% 4 3 3 4 4 8% 47%	1900
May	1st to 10th	Night	17% 7% 2 6% 4 4 4 4 5% 8% 39%	3130
	11th to 20th	Night	15% 6% 2 5% 4 4 4 3 5% 7% 45%	2895
	21st to end	Night	14% 6% 2 6% 5% 4 5% 4 6% 7% 42%	3090
June	1st to 10th	Night	5% 4 1 5% 3 3 4 5% 7% 10% 53%	1534
	11th to 20th	Night	3 4 2 4 3 4 3 4 5% 8% 60%	1520
	21st to end	Night	3 4 1 3 4 4 4 4 6% 8% 61%	1655
July	1st to 10th	Night	7% 5% 1 4 5% 5% 4 4 7% 11% 47%	2850
	11th to 20th	Night	5% 3 1 4 2 4 4 4 8% 11% 54%	2850
	21st to end	Night	9% 8% 3 6% 5% 5% 4 4 6% 8% 41%	3098
August	1st to 10th	Night	2 1 1 2 3 3 2 3 5% 8% 70%	2836
	11th to 20th	Night	4 3 1 4 4 4 4 4 7% 10% 55%	3100
	21st to end	Night	3 3 1 5% 4 4 5% 4 6% 9% 56%	3476
September	1st to 10th	Night	6% 5% 2 5% 3 3 5% 4 5% 7% 55%	1900
	11th to 20th	Night	10% 4 2 5% 4 3 4 3 5% 8% 52%	1840
	21st to end	Night	8% 3 1 5% 3 3 3 3 5% 6% 60%	2048
October	1st to 10th	Night	8% 4 2 5% 3 4 3 3 4 6% 60%	2160
	11th to 20th	Night	10% 4 2 5% 2 3 3 2 4 5% 59%	2160
	21st to end	Night	16% 5% 2 5% 3 3 3 3 2 3 55%	2376
November	1st to 10th	Night	12% 5% 2 4 3 2 3 2 4 6% 58%	2220
	11th to 20th	Night	11% 4 1 4 3 3 3 3 4 6% 57%	2356
	21st to end	Night	14% 6% 2 5% 4 4 3 3 4 5% 50%	2489
December	1st to 10th	Night	18% 6% 2 5% 4 3 3 3 4 4 47%	2660
	11th to 20th	Night	16% 6% 2 6% 5% 3 3 2 4 4 49%	3279
	21st to end	Night	15% 7% 2 7% 5% 4 4 3 4 5% 43%	4621

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	44% 3 6% 24% 20% 4	2848
	11th to 20th	Day	40% 4 10% 23% 21% 2	2850
	21st to end	Day	44% 3 6% 17% 24% 5%	3135
February	1st to 10th	Day	46% 5% 9% 21% 16% 4	1710
	11th to 20th	Day	46% 3 7% 19% 19% 6%	1813
	21st to end	Day	50% 4 6% 15% 17% 8%	1606
March	1st to 10th	Day	49% 4 7% 13% 17% 9%	3436
	11th to 20th	Day	39% 6% 9% 23% 19% 4	3480
	21st to end	Day	44% 4 8% 21% 20% 1	3832
April	1st to 10th	Day	37% 6% 9% 24% 20% 5%	2280
	11th to 20th	Day	40% 4 9% 22% 17% 7%	2254
	21st to end	Day	42% 6% 10% 21% 20% 2	2280
May	1st to 10th	Day	44% 7% 12% 22% 14% 2	3800
	11th to 20th	Day	37% 9% 12% 26% 15% 1	4008
	21st to end	Day	43% 10% 12% 22% 11% 2	4489
June	1st to 10th	Day	34% 9% 14% 25% 17% 2	2636
	11th to 20th	Day	29% 7% 14% 30% 18% 2	2660
	21st to end	Day	26% 8% 13% 28% 20% 4	2515
July	1st to 10th	Day	33% 8% 15% 31% 11% 1	4056
	11th to 20th	Day	26% 6% 10% 34% 22% 3	4051
	21st to end	Day	46% 7% 15% 23% 8%	4325
August	1st to 10th	Day	20% 6% 16% 29% 24% 5%	4076
	11th to 20th	Day	37% 6% 13% 32% 10% 1	3765
	21st to end	Day	29% 7% 12% 29% 20% 3	4179
September	1st to 10th	Day	35% 7% 11% 21% 18% 8%	2280
	11th to 20th	Day	35% 7% 11% 18% 23% 6%	2197
	21st to end	Day	31% 5% 7% 22% 26% 9%	1890
October	1st to 10th	Day	27% 5% 10% 23% 27% 9%	1800
	11th to 20th	Day	32% 4 6% 19% 29% 10%	1800
	21st to end	Day	35% 4 5% 22% 23% 9%	1980
November	1st to 10th	Day	29% 4 8% 27% 24% 8%	1858
	11th to 20th	Day	29% 4 8% 21% 28% 9%	1821
	21st to end	Day	44% 3 6% 17% 24% 6%	1688
December	1st to 10th	Day	42% 3 8% 24% 17% 6%	1520
	11th to 20th	Day	43% 3 6% 20% 22% 5%	1915
	21st to end	Day	44% 5% 10% 19% 16% 5%	3039
January	1st to 10th	Night	42% 3 6% 19% 27% 3	4108
	11th to 20th	Night	37% 3 10% 21% 25% 4	4120
	21st to end	Night	42% 4 10% 18% 23% 4	4532
February	1st to 10th	Night	45% 3 7% 20% 18% 6%	2470
	11th to 20th	Night	43% 3 6% 21% 20% 6%	2262
	21st to end	Night	41% 3 8% 17% 21% 9%	1863
March	1st to 10th	Night	42% 6% 9% 13% 18% 11%	3419
	11th to 20th	Night	38% 4 8% 26% 18% 6%	3480
	21st to end	Night	39% 5% 8% 24% 22% 2	3797
April	1st to 10th	Night	33% 5% 10% 23% 20% 9%	1900
	11th to 20th	Night	32% 5% 9% 23% 21% 10%	1875
	21st to end	Night	35% 5% 10% 24% 22% 3	1900
May	1st to 10th	Night	44% 6% 12% 21% 14% 4	3160
	11th to 20th	Night	37% 7% 13% 26% 15% 1	2896
	21st to end	Night	39% 9% 13% 23% 13% 2	3099
June	1st to 10th	Night	23% 9% 15% 30% 21% 2	1534
	11th to 20th	Night	21% 6% 13% 29% 26% 5%	1520
	21st to end	Night	20% 5% 13% 31% 24% 7%	1655
July	1st to 10th	Night	29% 8% 17% 29% 16% 1	2805
	11th to 20th	Night	21% 6% 12% 34% 22% 4	2796
	21st to end	Night	39% 8% 12% 26% 15%	2999
August	1st to 10th	Night	13% 5% 16% 34% 26% 6%	2826
	11th to 20th	Night	22% 6% 19% 36% 15% 2	3130
	21st to end	Night	23% 6% 12% 28% 28% 3	3476
September	1st to 10th	Night	27% 7% 11% 25% 21% 9%	1900
	11th to 20th	Night	30% 6% 10% 21% 26% 7%	1840
	21st to end	Night	25% 5% 9% 22% 29% 10%	2048
October	1st to 10th	Night	26% 4 11% 24% 24% 12%	2160
	11th to 20th	Night	28% 4 6% 18% 32% 12%	2160
	21st to end	Night	36% 3 5% 19% 27% 10%	2376
November	1st to 10th	Night	29% 3 7% 23% 27% 11%	2220
	11th to 20th	Night	29% 3 6% 24% 27% 11%	2356
	21st to end	Night	37% 3 6% 19% 28% 6%	2489
December	1st to 10th	Night	41% 3 8% 20% 21% 7%	2660
	11th to 20th	Night	40% 3 5% 20% 25% 6%	3281
	21st to end	Night	41% 5% 9% 21% 21% 3	4621

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	26% 15% 36% 16% 6% 1	270
	11th to 20th	Day	29% 19% 32% 18% 2	270
	21st to end	Day	21% 22% 38% 13% 6%	297
February	1st to 10th	Day	25% 16% 35% 17% 6% 1	270
	11th to 20th	Day	29% 23% 32% 12% 3 1	270
	21st to end	Day	36% 19% 30% 12% 3	225
March	1st to 10th	Day	27% 18% 34% 14% 7%	270
	11th to 20th	Day	24% 22% 37% 16% 1	270
	21st to end	Day	24% 21% 37% 14% 4	303
April	1st to 10th	Day	19% 18% 34% 21% 7% 1	460
	11th to 20th	Day	22% 13% 33% 22% 8% 1	452
	21st to end	Day	21% 13% 33% 20% 11% 2	460
May	1st to 10th	Day	17% 13% 32% 27% 10% 1	463
	11th to 20th	Day	14% 6% 27% 32% 18% 3	623
	21st to end	Day	10% 6% 22% 34% 21% 7%	734
June	1st to 10th	Day	11% 3 17% 33% 28% 9%	680
	11th to 20th	Day	5% 3 15% 36% 31% 9%	680
	21st to end	Day	5% 3 17% 37% 28% 10%	680
July	1st to 10th	Day	6% 3 13% 30% 34% 14%	671
	11th to 20th	Day	5% 3 11% 31% 35% 16%	668
	21st to end	Day	8% 1 7% 32% 34% 16%	739
August	1st to 10th	Day	6% 3 10% 35% 35% 11%	675
	11th to 20th	Day	14% 1 9% 30% 34% 12%	479
	21st to end	Day	11% 1 5% 22% 43% 18%	539
September	1st to 10th	Day	10% 2 9% 28% 39% 12%	490
	11th to 20th	Day	11% 3 12% 25% 36% 13%	463
	21st to end	Day	9% 3 19% 35% 26% 8%	296
October	1st to 10th	Day	9% 4 27% 33% 22% 5%	270
	11th to 20th	Day	14% 12% 33% 26% 13% 1	270
	21st to end	Day	26% 12% 33% 18% 8% 3	297
November	1st to 10th	Day	16% 9% 31% 26% 15% 2	270
	11th to 20th	Day	13% 12% 40% 28% 6% 1	270
	21st to end	Day	27% 13% 26% 23% 8% 1	270
December	1st to 10th	Day	23% 19% 31% 18% 7% 1	270
	11th to 20th	Day	26% 14% 31% 19% 10%	270
	21st to end	Day	23% 19% 39% 14% 3 1	297
January	1st to 10th	Night	22% 8% 35% 28% 7%	950
	11th to 20th	Night	22% 12% 35% 26% 5% 1	950
	21st to end	Night	21% 10% 37% 28% 3	1045
February	1st to 10th	Night	25% 11% 32% 26% 5%	950
	11th to 20th	Night	24% 11% 39% 24% 2	786
	21st to end	Night	25% 15% 34% 23% 3	607
March	1st to 10th	Night	20% 9% 33% 34% 5%	570
	11th to 20th	Night	19% 12% 36% 26% 6%	570
	21st to end	Night	18% 12% 35% 28% 7%	627
April	1st to 10th	Night	16% 12% 36% 28% 7%	570
	11th to 20th	Night	14% 9% 39% 25% 13%	563
	21st to end	Night	15% 9% 36% 30% 9% 1	570
May	1st to 10th	Night	13% 6% 26% 43% 11%	570
	11th to 20th	Night	15% 6% 26% 34% 17% 2	561
	21st to end	Night	10% 4 22% 34% 26% 4	617
June	1st to 10th	Night	6% 2 12% 40% 36% 4	570
	11th to 20th	Night	3 2 11% 46% 34% 4	570
	21st to end	Night	3 1 11% 43% 36% 5%	570
July	1st to 10th	Night	3 2 10% 34% 45% 7%	555
	11th to 20th	Night	3 1 7% 34% 45% 9%	552
	21st to end	Night	6% 1 7% 35% 43% 9%	624
August	1st to 10th	Night	3 1 4 38% 46% 7%	567
	11th to 20th	Night	5% 1 6% 38% 43% 7%	564
	21st to end	Night	6% 1 7% 32% 46% 7%	627
September	1st to 10th	Night	8% 2 8% 36% 41% 6%	570
	11th to 20th	Night	12% 1 10% 32% 41% 3	552
	21st to end	Night	8% 2 14% 37% 34% 4	638
October	1st to 10th	Night	10% 2 17% 35% 32% 3	720
	11th to 20th	Night	12% 5% 27% 37% 18% 1	720
	21st to end	Night	19% 6% 27% 31% 15% 1	792
November	1st to 10th	Night	14% 6% 23% 37% 19% 1	740
	11th to 20th	Night	13% 9% 29% 38% 12%	760
	21st to end	Night	17% 9% 29% 33% 12%	779
December	1st to 10th	Night	22% 7% 31% 33% 7%	950
	11th to 20th	Night	21% 9% 30% 32% 7%	950
	21st to end	Night	22% 12% 31% 29% 5%	1045

Page generated at 2024-09-11 09:00:07. Version ac07

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