Little River Canyon National Preserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little River Canyon National Preserve clear sky chart from 2005-11-06 to 2024-11-28.

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	14% 6% 2 6% 4 4 5% 4 6% 7% 41%	101093
	Night	14% 6% 2 6% 4 4 4 3 5% 7% 44%	98413
Transparency	Day	40% 4 11% 22% 18% 5%	104899
	Night	38% 4 10% 22% 20% 6%	102745
Seeing	Day	17% 9% 21% 24% 19% 10%	14741
	Night	16% 8% 21% 29% 21% 4	24752

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	19% 11% 3 6% 3 4 5% 4 5% 5% 36%	2836
	11th to 20th	Day	19% 7% 2 6% 4 3 3 3 3 4 45%	2840
	21st to end	Day	26% 8% 2 5% 3 2 3 2 4 5% 40%	3394
February	1st to 10th	Day	20% 10% 3 4 4 4 3 3 5% 7% 38%	1900
	11th to 20th	Day	24% 7% 2 6% 5% 4 3 2 5% 4 38%	1848
	21st to end	Day	23% 9% 3 6% 4 3 4 2 4 4 38%	1570
March	1st to 10th	Day	25% 9% 3 6% 4 4 5% 3 5% 6% 31%	3120
	11th to 20th	Day	16% 7% 2 5% 5% 4 4 3 5% 6% 45%	3439
	21st to end	Day	17% 7% 3 7% 5% 4 4 4 6% 7% 38%	3835
April	1st to 10th	Day	14% 6% 2 6% 4 4 4 4 6% 7% 43%	2280
	11th to 20th	Day	13% 6% 3 5% 4 5% 4 4 4 6% 46%	2254
	21st to end	Day	11% 4 1 6% 4 5% 5% 4 7% 7% 47%	2346
May	1st to 10th	Day	12% 6% 2 6% 4 5% 5% 3 6% 8% 42%	4082
	11th to 20th	Day	17% 7% 2 6% 4 4 4 3 6% 8% 38%	4081
	21st to end	Day	11% 5% 2 6% 4 5% 5% 4 7% 9% 42%	4476
June	1st to 10th	Day	11% 7% 2 7% 5% 6% 6% 5% 8% 9% 34%	2470
	11th to 20th	Day	5% 4 2 6% 5% 5% 6% 5% 8% 10% 44%	2470
	21st to end	Day	8% 6% 2 7% 5% 6% 6% 5% 9% 9% 38%	2470
July	1st to 10th	Day	9% 6% 2 7% 6% 6% 8% 6% 8% 12% 30%	4120
	11th to 20th	Day	9% 6% 2 6% 6% 7% 7% 7% 8% 11% 32%	4120
	21st to end	Day	14% 10% 4 10% 7% 7% 7% 6% 7% 9% 19%	4466
August	1st to 10th	Day	5% 3 2 5% 4 5% 5% 6% 9% 11% 47%	3952
	11th to 20th	Day	7% 4 2 7% 4 4 6% 5% 8% 11% 42%	3729
	21st to end	Day	8% 4 2 5% 4 4 5% 4 6% 7% 51%	4180
September	1st to 10th	Day	11% 7% 2 5% 4 4 5% 5% 7% 9% 39%	2179
	11th to 20th	Day	16% 4 2 6% 4 5% 5% 4 6% 6% 41%	2090
	21st to end	Day	14% 6% 2 5% 3 3 3 3 5% 6% 49%	2090
October	1st to 10th	Day	11% 5% 2 5% 3 4 3 3 4 5% 55%	2090
	11th to 20th	Day	10% 6% 2 5% 3 3 4 3 4 6% 56%	2066
	21st to end	Day	15% 4 2 4 3 4 3 3 3 5% 54%	1978
November	1st to 10th	Day	13% 6% 2 4 3 3 4 2 4 5% 53%	1762
	11th to 20th	Day	14% 5% 2 5% 3 3 4 3 4 6% 50%	1800
	21st to end	Day	17% 6% 1 4 3 3 4 3 5% 6% 45%	1773
December	1st to 10th	Day	24% 7% 2 5% 3 4 4 3 5% 6% 37%	1710
	11th to 20th	Day	19% 7% 3 6% 4 4 5% 3 4 5% 41%	2153
	21st to end	Day	21% 8% 3 7% 5% 4 4 3 5% 6% 34%	3124
January	1st to 10th	Night	19% 10% 3 6% 3 3 4 3 4 5% 40%	4109
	11th to 20th	Night	19% 8% 3 5% 3 3 3 3 4 5% 44%	4120
	21st to end	Night	24% 12% 2 5% 3 3 3 2 3 4 39%	4244
February	1st to 10th	Night	18% 7% 3 6% 4 3 3 3 4 7% 42%	2280
	11th to 20th	Night	21% 6% 3 6% 5% 3 3 3 3 5% 41%	2218
	21st to end	Night	22% 7% 2 6% 4 4 4 3 5% 6% 36%	1884
March	1st to 10th	Night	27% 9% 3 7% 4 3 3 3 4 5% 33%	3733
	11th to 20th	Night	12% 5% 1 5% 4 4 4 3 6% 7% 48%	3520
	21st to end	Night	17% 8% 3 6% 5% 4 4 4 4 5% 40%	3817
April	1st to 10th	Night	12% 4 2 5% 3 4 4 4 6% 8% 48%	1907
	11th to 20th	Night	15% 5% 2 5% 3 3 3 3 5% 7% 49%	1875
	21st to end	Night	10% 4 3 5% 5% 3 4 3 5% 6% 52%	1833
May	1st to 10th	Night	12% 6% 3 6% 5% 5% 4 4 6% 8% 41%	2813
	11th to 20th	Night	17% 6% 2 6% 4 4 4 4 7% 8% 39%	2812
	21st to end	Night	7% 5% 2 6% 4 5% 5% 5% 6% 11% 45%	3079
June	1st to 10th	Night	8% 5% 2 7% 4 6% 5% 5% 8% 10% 39%	1710
	11th to 20th	Night	3 3 2 5% 5% 4 4 4 6% 12% 52%	1710
	21st to end	Night	6% 5% 1 5% 4 5% 6% 5% 7% 11% 45%	1710
July	1st to 10th	Night	8% 6% 2 8% 6% 6% 6% 4 8% 12% 34%	2840
	11th to 20th	Night	8% 4 2 5% 5% 4 4 5% 7% 13% 42%	2840
	21st to end	Night	14% 9% 4 9% 6% 6% 6% 5% 7% 9% 25%	3087
August	1st to 10th	Night	4 4 2 4 3 3 5% 4 8% 11% 52%	2973
	11th to 20th	Night	8% 5% 2 5% 3 4 4 4 6% 9% 50%	3100
	21st to end	Night	8% 4 1 4 3 3 4 3 5% 7% 57%	3476
September	1st to 10th	Night	9% 5% 2 6% 6% 4 4 4 6% 8% 44%	1981
	11th to 20th	Night	14% 5% 2 6% 5% 4 4 4 5% 8% 42%	2090
	21st to end	Night	12% 5% 2 5% 4 4 4 3 4 6% 52%	2090
October	1st to 10th	Night	11% 4 2 5% 3 2 3 2 4 6% 60%	2090
	11th to 20th	Night	12% 5% 2 5% 4 3 3 3 4 4 56%	2114
	21st to end	Night	13% 5% 2 5% 3 3 4 2 4 6% 54%	2616
November	1st to 10th	Night	13% 4 2 5% 3 3 3 3 4 5% 53%	2536
	11th to 20th	Night	13% 6% 2 4 3 3 3 3 4 5% 53%	2600
	21st to end	Night	16% 6% 2 4 3 3 4 4 5% 6% 47%	2562
December	1st to 10th	Night	21% 7% 2 6% 4 4 4 3 5% 5% 38%	2470
	11th to 20th	Night	18% 6% 2 5% 3 3 3 3 4 6% 47%	3042
	21st to end	Night	21% 7% 3 7% 4 4 4 3 6% 8% 32%	4532

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	51% 2 5% 17% 22% 3	2837
	11th to 20th	Day	44% 2 6% 22% 23% 2	2840
	21st to end	Day	48% 2 6% 20% 20% 4	3394
February	1st to 10th	Day	47% 2 7% 21% 20% 3	1900
	11th to 20th	Day	50% 2 4 19% 19% 6%	1858
	21st to end	Day	50% 2 6% 16% 20% 6%	1570
March	1st to 10th	Day	54% 3 8% 12% 14% 9%	3120
	11th to 20th	Day	42% 3 5% 22% 23% 6%	3439
	21st to end	Day	46% 3 11% 21% 16% 4	3835
April	1st to 10th	Day	39% 4 11% 22% 19% 6%	2280
	11th to 20th	Day	40% 3 7% 20% 24% 7%	2254
	21st to end	Day	35% 3 11% 29% 20% 3	2346
May	1st to 10th	Day	39% 3 13% 27% 15% 2	4120
	11th to 20th	Day	45% 3 12% 28% 12% 1	4085
	21st to end	Day	37% 4 12% 27% 18% 2	4489
June	1st to 10th	Day	43% 6% 15% 22% 13% 2	2470
	11th to 20th	Day	32% 6% 18% 26% 16% 2	2470
	21st to end	Day	39% 7% 16% 23% 13% 3	2470
July	1st to 10th	Day	42% 9% 22% 19% 7% 1	4055
	11th to 20th	Day	41% 8% 23% 21% 6% 1	4051
	21st to end	Day	58% 8% 14% 14% 5%	4324
August	1st to 10th	Day	26% 7% 14% 37% 14% 1	3939
	11th to 20th	Day	33% 7% 16% 27% 14% 3	3765
	21st to end	Day	31% 5% 14% 25% 22% 3	4179
September	1st to 10th	Day	40% 5% 16% 17% 16% 6%	2179
	11th to 20th	Day	42% 4 11% 22% 17% 3	2090
	21st to end	Day	36% 4 11% 20% 22% 8%	2090
October	1st to 10th	Day	24% 4 4 14% 39% 14%	3480
	11th to 20th	Day	22% 2 5% 19% 30% 23%	3410
	21st to end	Day	27% 3 6% 24% 30% 11%	3241
November	1st to 10th	Day	35% 3 6% 19% 28% 9%	1762
	11th to 20th	Day	36% 3 6% 19% 27% 9%	1800
	21st to end	Day	39% 3 7% 20% 24% 6%	1773
December	1st to 10th	Day	49% 3 6% 18% 19% 5%	1710
	11th to 20th	Day	48% 2 5% 20% 20% 6%	2150
	21st to end	Day	51% 2 7% 21% 17% 2	3124
January	1st to 10th	Night	47% 2 4 21% 23% 3	4109
	11th to 20th	Night	44% 3 5% 24% 18% 6%	4120
	21st to end	Night	51% 1 4 17% 22% 4	4244
February	1st to 10th	Night	44% 2 6% 20% 22% 5%	2280
	11th to 20th	Night	48% 2 5% 19% 18% 7%	2219
	21st to end	Night	50% 3 6% 16% 19% 7%	1884
March	1st to 10th	Night	55% 2 7% 13% 16% 6%	3733
	11th to 20th	Night	35% 3 8% 21% 24% 9%	3520
	21st to end	Night	47% 2 6% 22% 19% 4	3817
April	1st to 10th	Night	34% 3 12% 22% 22% 6%	1907
	11th to 20th	Night	36% 3 6% 22% 23% 11%	1875
	21st to end	Night	34% 3 9% 29% 21% 5%	1833
May	1st to 10th	Night	41% 3 13% 23% 18% 2	2840
	11th to 20th	Night	43% 4 13% 27% 12% 1	2813
	21st to end	Night	33% 4 14% 27% 19% 2	3087
June	1st to 10th	Night	39% 6% 15% 23% 15% 2	1710
	11th to 20th	Night	25% 5% 22% 27% 19% 2	1710
	21st to end	Night	31% 7% 19% 22% 16% 5%	1710
July	1st to 10th	Night	40% 9% 22% 20% 8% 2	2795
	11th to 20th	Night	32% 7% 26% 25% 8% 2	2786
	21st to end	Night	53% 9% 14% 16% 6% 1	2988
August	1st to 10th	Night	24% 6% 15% 40% 14% 1	2962
	11th to 20th	Night	30% 6% 17% 28% 17% 2	3130
	21st to end	Night	27% 5% 14% 20% 30% 4	3476
September	1st to 10th	Night	37% 5% 17% 19% 16% 6%	1981
	11th to 20th	Night	40% 6% 12% 19% 21% 3	2090
	21st to end	Night	33% 4 9% 22% 23% 8%	2090
October	1st to 10th	Night	21% 5% 6% 18% 34% 16%	3480
	11th to 20th	Night	20% 1 3 18% 31% 26%	3509
	21st to end	Night	24% 2 4 26% 31% 13%	4303
November	1st to 10th	Night	33% 3 8% 20% 24% 11%	2536
	11th to 20th	Night	34% 2 5% 20% 29% 11%	2600
	21st to end	Night	39% 3 6% 23% 23% 7%	2562
December	1st to 10th	Night	49% 2 8% 19% 19% 4	2470
	11th to 20th	Night	40% 2 6% 20% 28% 5%	3044
	21st to end	Night	51% 2 6% 22% 17% 2	4532

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% 23% 34% 13% 3	270
	11th to 20th	Day	28% 21% 32% 13% 4 2	270
	21st to end	Day	23% 21% 38% 13% 5%	297
February	1st to 10th	Day	29% 18% 32% 17% 4	270
	11th to 20th	Day	38% 17% 31% 11% 2	270
	21st to end	Day	31% 22% 37% 8% 1	225
March	1st to 10th	Day	26% 16% 35% 19% 3 1	270
	11th to 20th	Day	24% 17% 31% 20% 8% 1	432
	21st to end	Day	20% 16% 35% 22% 7%	506
April	1st to 10th	Day	21% 14% 28% 20% 15% 2	460
	11th to 20th	Day	17% 13% 31% 25% 13% 1	452
	21st to end	Day	15% 12% 27% 27% 16% 4	460
May	1st to 10th	Day	15% 9% 27% 27% 16% 5%	463
	11th to 20th	Day	14% 6% 18% 30% 21% 11%	487
	21st to end	Day	14% 4 13% 27% 24% 16%	529
June	1st to 10th	Day	15% 3 15% 28% 24% 14%	490
	11th to 20th	Day	6% 2 15% 28% 25% 23%	490
	21st to end	Day	12% 3 11% 28% 27% 19%	490
July	1st to 10th	Day	10% 2 8% 24% 32% 23%	485
	11th to 20th	Day	11% 2 7% 22% 31% 27%	484
	21st to end	Day	11% 3 10% 19% 33% 26%	532
August	1st to 10th	Day	10% 3 9% 25% 32% 20%	486
	11th to 20th	Day	12% 3 7% 32% 30% 16%	479
	21st to end	Day	16% 3 6% 27% 28% 21%	539
September	1st to 10th	Day	12% 5% 10% 25% 31% 17%	490
	11th to 20th	Day	17% 3 12% 23% 32% 13%	490
	21st to end	Day	16% 4 14% 26% 30% 10%	490
October	1st to 10th	Day	13% 3 21% 32% 22% 9%	490
	11th to 20th	Day	12% 9% 25% 31% 21% 2	490
	21st to end	Day	17% 10% 21% 32% 18% 3	427
November	1st to 10th	Day	23% 9% 26% 28% 12% 2	300
	11th to 20th	Day	18% 15% 35% 24% 8%	300
	21st to end	Day	19% 14% 34% 23% 9% 2	291
December	1st to 10th	Day	29% 15% 32% 18% 5% 1	270
	11th to 20th	Day	25% 16% 32% 20% 6% 1	270
	21st to end	Day	32% 15% 30% 16% 6%	297
January	1st to 10th	Night	25% 15% 33% 22% 6%	760
	11th to 20th	Night	22% 17% 27% 28% 6%	760
	21st to end	Night	24% 12% 35% 26% 3	836
February	1st to 10th	Night	22% 12% 31% 31% 4	760
	11th to 20th	Night	25% 15% 31% 26% 2	743
	21st to end	Night	25% 15% 35% 24% 2	628
March	1st to 10th	Night	20% 14% 32% 30% 4	760
	11th to 20th	Night	18% 13% 31% 28% 9% 1	760
	21st to end	Night	19% 13% 25% 31% 10%	836
April	1st to 10th	Night	14% 11% 29% 30% 16% 1	577
	11th to 20th	Night	18% 10% 26% 31% 14% 1	563
	21st to end	Night	13% 6% 24% 37% 19% 1	570
May	1st to 10th	Night	11% 6% 22% 35% 24% 2	570
	11th to 20th	Night	14% 5% 17% 33% 25% 6%	561
	21st to end	Night	12% 1 10% 33% 37% 7%	617
June	1st to 10th	Night	10% 3 9% 37% 35% 6%	570
	11th to 20th	Night	4 2 10% 31% 38% 15%	570
	21st to end	Night	7% 2 8% 30% 43% 10%	570
July	1st to 10th	Night	8% 2 6% 22% 46% 16%	555
	11th to 20th	Night	9% 2 5% 21% 46% 18%	552
	21st to end	Night	10% 3 6% 24% 43% 14%	624
August	1st to 10th	Night	7% 1 5% 27% 46% 14%	567
	11th to 20th	Night	14% 2 9% 26% 41% 9%	564
	21st to end	Night	15% 2 7% 24% 42% 10%	627
September	1st to 10th	Night	10% 2 9% 31% 37% 11%	651
	11th to 20th	Night	16% 3 11% 28% 37% 5%	760
	21st to end	Night	14% 3 15% 29% 35% 3	760
October	1st to 10th	Night	12% 3 20% 34% 24% 7%	760
	11th to 20th	Night	14% 7% 23% 34% 20% 2	760
	21st to end	Night	15% 7% 22% 35% 18% 2	836
November	1st to 10th	Night	14% 7% 23% 33% 20% 2	780
	11th to 20th	Night	16% 9% 31% 31% 13% 1	800
	21st to end	Night	20% 11% 25% 32% 12% 1	789
December	1st to 10th	Night	25% 12% 26% 27% 9% 1	760
	11th to 20th	Night	23% 10% 30% 27% 9%	760
	21st to end	Night	28% 11% 26% 28% 7%	836

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