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 2025-02-21.

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%	108351
	Night	13% 6% 2 5% 4 3 3 3 5% 6% 50%	110387
Transparency	Day	37% 5% 10% 24% 20% 5%	111996
	Night	33% 4 9% 24% 22% 7%	114883
Seeing	Day	15% 9% 23% 26% 21% 7%	15668
	Night	15% 7% 25% 33% 18% 2	25623

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	17% 7% 2 6% 3 3 3 2 4 5% 48%	4077
	11th to 20th	Day	11% 8% 2 5% 4 3 3 3 4 5% 52%	4080
	21st to end	Day	22% 7% 2 4 3 2 2 2 3 4 49%	4488
February	1st to 10th	Day	22% 8% 3 5% 4 3 3 4 3 5% 40%	1800
	11th to 20th	Day	18% 9% 3 6% 4 3 3 3 4 5% 42%	1901
	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% 45%	2280
	21st to end	Day	10% 5% 2 5% 4 4 4 3 5% 6% 53%	1994
October	1st to 10th	Day	8% 4 1 4 3 3 3 3 5% 6% 59%	1900
	11th to 20th	Day	15% 4 1 3 2 3 2 2 3 6% 57%	1900
	21st to end	Day	17% 5% 2 4 3 3 3 2 3 5% 53%	2090
November	1st to 10th	Day	13% 6% 2 4 3 3 4 2 4 5% 55%	1958
	11th to 20th	Day	11% 6% 1 4 3 3 3 3 5% 7% 55%	1916
	21st to end	Day	18% 7% 2 6% 3 2 4 3 4 6% 45%	1776
December	1st to 10th	Day	18% 8% 3 5% 4 4 3 2 3 4 46%	2610
	11th to 20th	Day	19% 9% 3 6% 4 3 3 3 4 4 43%	3008
	21st to end	Day	19% 7% 3 7% 4 4 4 3 5% 5% 40%	4364
January	1st to 10th	Night	17% 6% 2 5% 3 2 3 2 4 5% 51%	5888
	11th to 20th	Night	14% 5% 1 4 3 3 2 2 3 4 59%	5900
	21st to end	Night	22% 7% 2 5% 3 2 3 2 3 4 48%	6490
February	1st to 10th	Night	22% 8% 3 5% 3 3 3 3 3 6% 42%	2600
	11th to 20th	Night	19% 8% 3 6% 4 3 3 3 3 5% 44%	2383
	21st to end	Night	21% 6% 2 4 3 3 3 2 4 5% 46%	1864
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% 5% 2 5% 4 3 4 3 5% 8% 52%	1900
	21st to end	Night	8% 4 2 5% 3 3 3 3 5% 6% 59%	2163
October	1st to 10th	Night	8% 4 2 5% 3 3 2 3 4 6% 61%	2280
	11th to 20th	Night	9% 4 2 5% 2 3 2 2 4 5% 61%	2280
	21st to end	Night	16% 5% 2 5% 3 3 3 3 3 3 55%	2508
November	1st to 10th	Night	13% 5% 2 5% 4 2 3 2 4 5% 56%	2340
	11th to 20th	Night	11% 4 1 4 3 3 3 3 4 6% 57%	2480
	21st to end	Night	14% 6% 2 5% 4 4 3 3 4 5% 52%	2620
December	1st to 10th	Night	16% 6% 2 5% 4 2 3 3 4 4 51%	4580
	11th to 20th	Night	17% 10% 3 6% 5% 3 3 2 3 4 45%	5199
	21st to end	Night	19% 7% 2 6% 4 3 4 3 4 5% 43%	6607

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	40% 3 9% 27% 18% 2	4078
	11th to 20th	Day	36% 3 8% 23% 26% 4	4080
	21st to end	Day	41% 3 4 17% 26% 9%	4488
February	1st to 10th	Day	47% 5% 9% 21% 15% 4	1800
	11th to 20th	Day	46% 3 7% 20% 19% 5%	1911
	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	36% 7% 10% 18% 23% 6%	2280
	21st to end	Day	32% 5% 7% 22% 25% 9%	1994
October	1st to 10th	Day	15% 3 6% 13% 34% 29%	3160
	11th to 20th	Day	18% 2 4 20% 38% 18%	3140
	21st to end	Day	31% 3 4 27% 28% 7%	3428
November	1st to 10th	Day	31% 4 8% 26% 23% 8%	1958
	11th to 20th	Day	29% 4 8% 21% 27% 11%	1916
	21st to end	Day	43% 3 6% 18% 24% 6%	1776
December	1st to 10th	Day	44% 3 6% 26% 19% 3	2610
	11th to 20th	Day	45% 3 5% 22% 20% 5%	3005
	21st to end	Day	45% 4 8% 25% 14% 4	4364
January	1st to 10th	Night	37% 2 7% 28% 23% 2	5888
	11th to 20th	Night	31% 3 7% 20% 32% 7%	5900
	21st to end	Night	43% 3 7% 17% 25% 5%	6490
February	1st to 10th	Night	46% 3 7% 21% 18% 6%	2600
	11th to 20th	Night	44% 3 6% 21% 19% 6%	2384
	21st to end	Night	41% 3 8% 17% 21% 9%	1864
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	31% 6% 10% 21% 26% 7%	1900
	21st to end	Night	26% 5% 10% 22% 28% 10%	2163
October	1st to 10th	Night	16% 3 6% 15% 28% 32%	3800
	11th to 20th	Night	16% 2 4 16% 38% 25%	3779
	21st to end	Night	28% 3 4 22% 30% 13%	4120
November	1st to 10th	Night	32% 3 7% 22% 26% 11%	2340
	11th to 20th	Night	29% 3 6% 23% 27% 12%	2480
	21st to end	Night	36% 4 7% 19% 28% 6%	2620
December	1st to 10th	Night	37% 2 6% 32% 19% 4	4580
	11th to 20th	Night	46% 2 4 20% 21% 7%	5201
	21st to end	Night	44% 4 9% 23% 17% 3	6607

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	24% 15% 37% 17% 5% 1	300
	11th to 20th	Day	26% 18% 33% 21% 2	300
	21st to end	Day	20% 20% 40% 14% 5%	330
February	1st to 10th	Day	26% 17% 33% 17% 6% 1	300
	11th to 20th	Day	30% 23% 33% 11% 2 1	300
	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	13% 3 11% 25% 36% 12%	490
	21st to end	Day	9% 4 19% 35% 25% 8%	327
October	1st to 10th	Day	8% 4 26% 35% 23% 5%	300
	11th to 20th	Day	13% 11% 31% 27% 15% 2	300
	21st to end	Day	25% 12% 32% 19% 10% 2	330
November	1st to 10th	Day	20% 10% 30% 25% 13% 2	300
	11th to 20th	Day	13% 13% 39% 29% 6% 1	300
	21st to end	Day	25% 13% 29% 23% 8% 1	300
December	1st to 10th	Day	23% 19% 33% 17% 7% 1	300
	11th to 20th	Day	26% 15% 32% 18% 9%	300
	21st to end	Day	24% 19% 37% 14% 4 1	330
January	1st to 10th	Night	22% 8% 34% 29% 6%	1000
	11th to 20th	Night	21% 12% 35% 27% 4 1	1000
	21st to end	Night	21% 10% 37% 29% 3	1100
February	1st to 10th	Night	25% 11% 32% 27% 5%	1000
	11th to 20th	Night	25% 11% 39% 22% 2	828
	21st to end	Night	25% 15% 34% 23% 3	608
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	13% 1 9% 32% 41% 3	570
	21st to end	Night	9% 2 15% 37% 33% 4	674
October	1st to 10th	Night	10% 2 17% 36% 33% 3	760
	11th to 20th	Night	12% 4 27% 38% 18% 1	760
	21st to end	Night	18% 6% 27% 32% 16% 1	836
November	1st to 10th	Night	15% 7% 23% 36% 18% 1	780
	11th to 20th	Night	13% 9% 29% 38% 12%	800
	21st to end	Night	16% 9% 30% 33% 12%	820
December	1st to 10th	Night	22% 7% 31% 33% 7%	1000
	11th to 20th	Night	21% 9% 30% 32% 7%	1000
	21st to end	Night	23% 12% 30% 29% 6%	1100

Page generated at 2025-02-18 02:26:31. Version ac07

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