Walnut Point State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Walnut Point State Park clear sky chart from 2005-11-06 to 2025-01-07.

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 7% 5% 4 4 4 6% 7% 38%	104874
	Night	15% 9% 3 7% 4 4 4 3 5% 6% 40%	104250
Transparency	Day	43% 6% 12% 23% 15% 2	108491
	Night	43% 5% 11% 23% 16% 2	108774
Seeing	Day	15% 9% 27% 25% 17% 6%	15842
	Night	17% 9% 29% 30% 14% 1	25747

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% 12% 8% 15% 5% 5% 4 4 4 6% 23%	2575
	11th to 20th	Day	15% 10% 7% 12% 6% 8% 7% 7% 6% 4 18%	2530
	21st to end	Day	24% 21% 6% 9% 4 3 4 2 3 5% 19%	2984
February	1st to 10th	Day	16% 12% 5% 11% 6% 4 4 3 5% 5% 29%	1826
	11th to 20th	Day	16% 10% 4 9% 6% 5% 4 4 5% 6% 31%	1848
	21st to end	Day	16% 14% 4 8% 4 4 4 3 4 6% 33%	1570
March	1st to 10th	Day	20% 17% 4 7% 3 3 3 2 3 4 33%	3120
	11th to 20th	Day	12% 8% 3 6% 4 4 4 3 5% 7% 45%	3268
	21st to end	Day	15% 11% 5% 8% 5% 5% 5% 4 5% 7% 30%	4165
April	1st to 10th	Day	15% 9% 3 6% 5% 4 4 4 6% 8% 35%	2280
	11th to 20th	Day	16% 9% 3 6% 4 4 3 4 4 5% 41%	2254
	21st to end	Day	21% 8% 2 7% 5% 4 4 4 5% 6% 35%	2332
May	1st to 10th	Day	17% 8% 3 7% 5% 4 5% 4 7% 10% 30%	4082
	11th to 20th	Day	18% 7% 3 7% 5% 4 4 3 5% 8% 37%	4103
	21st to end	Day	9% 5% 2 6% 5% 5% 5% 4 6% 9% 44%	4824
June	1st to 10th	Day	9% 6% 2 5% 5% 4 5% 4 6% 9% 44%	2660
	11th to 20th	Day	8% 4 1 5% 5% 5% 5% 4 6% 8% 48%	2660
	21st to end	Day	9% 5% 2 6% 6% 5% 5% 4 7% 9% 43%	2660
July	1st to 10th	Day	14% 5% 2 6% 4 4 5% 4 7% 10% 39%	4440
	11th to 20th	Day	6% 5% 2 6% 4 5% 5% 5% 8% 11% 44%	4440
	21st to end	Day	9% 6% 3 6% 5% 4 6% 4 8% 10% 39%	4813
August	1st to 10th	Day	9% 4 1 5% 3 3 4 4 6% 9% 53%	4079
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 5% 7% 10% 42%	3729
	21st to end	Day	6% 3 2 5% 4 4 4 4 6% 10% 51%	4180
September	1st to 10th	Day	12% 5% 3 6% 4 4 4 4 4 7% 46%	2280
	11th to 20th	Day	9% 5% 2 4 4 5% 5% 4 6% 7% 49%	2146
	21st to end	Day	11% 4 2 5% 4 5% 4 3 6% 6% 49%	2090
October	1st to 10th	Day	11% 5% 1 5% 4 4 4 3 4 7% 52%	2074
	11th to 20th	Day	15% 7% 2 6% 3 3 4 3 5% 5% 45%	1900
	21st to end	Day	19% 9% 3 6% 3 4 3 3 4 6% 39%	1904
November	1st to 10th	Day	12% 6% 2 5% 3 3 3 2 5% 6% 51%	1762
	11th to 20th	Day	17% 10% 3 5% 5% 4 3 4 5% 5% 40%	1800
	21st to end	Day	16% 10% 4 7% 5% 4 4 3 4 5% 37%	1800
December	1st to 10th	Day	11% 10% 4 8% 5% 4 4 3 4 6% 43%	2706
	11th to 20th	Day	13% 16% 5% 10% 5% 5% 4 3 5% 7% 26%	3008
	21st to end	Day	28% 16% 6% 11% 5% 3 4 2 3 4 16%	3982
January	1st to 10th	Night	16% 14% 7% 10% 4 3 4 3 4 5% 29%	4513
	11th to 20th	Night	14% 18% 5% 11% 5% 7% 6% 4 4 3 22%	4440
	21st to end	Night	26% 15% 7% 8% 4 3 3 3 4 5% 23%	4679
February	1st to 10th	Night	18% 12% 4 9% 5% 5% 3 3 4 6% 31%	2352
	11th to 20th	Night	15% 9% 3 9% 5% 4 4 3 5% 6% 37%	2218
	21st to end	Night	19% 11% 3 7% 5% 4 4 3 4 5% 35%	1884
March	1st to 10th	Night	19% 15% 2 6% 4 4 3 2 3 5% 35%	3733
	11th to 20th	Night	13% 7% 3 5% 4 3 3 3 5% 6% 49%	3719
	21st to end	Night	19% 8% 3 8% 5% 5% 4 3 5% 6% 33%	3466
April	1st to 10th	Night	13% 9% 2 6% 5% 4 4 4 5% 7% 42%	1900
	11th to 20th	Night	18% 8% 2 5% 4 3 3 4 3 6% 43%	1875
	21st to end	Night	18% 9% 2 6% 4 5% 5% 5% 5% 4 37%	1847
May	1st to 10th	Night	17% 10% 3 6% 4 5% 4 4 5% 8% 34%	2813
	11th to 20th	Night	18% 7% 2 5% 4 4 4 4 5% 7% 40%	2786
	21st to end	Night	10% 6% 3 6% 4 5% 5% 4 5% 8% 44%	2743
June	1st to 10th	Night	8% 5% 2 6% 4 4 4 4 5% 7% 50%	1520
	11th to 20th	Night	8% 5% 2 5% 4 4 5% 3 6% 7% 52%	1520
	21st to end	Night	7% 4 2 5% 5% 4 4 4 6% 11% 46%	1520
July	1st to 10th	Night	11% 4 2 5% 5% 4 5% 3 5% 8% 48%	2530
	11th to 20th	Night	4 3 1 4 3 3 4 3 6% 10% 58%	2530
	21st to end	Night	8% 5% 3 8% 4 4 4 4 8% 10% 41%	2750
August	1st to 10th	Night	8% 3 2 5% 3 3 4 4 6% 9% 54%	2849
	11th to 20th	Night	7% 4 2 6% 4 5% 4 4 6% 8% 50%	3100
	21st to end	Night	6% 3 1 4 3 4 3 3 5% 9% 57%	3476
September	1st to 10th	Night	12% 4 2 4 3 4 3 3 4 7% 54%	1900
	11th to 20th	Night	6% 5% 2 5% 4 3 3 2 6% 8% 55%	2014
	21st to end	Night	11% 6% 2 4 4 3 4 4 5% 7% 51%	2090
October	1st to 10th	Night	10% 4 2 4 4 3 3 3 4 6% 57%	2103
	11th to 20th	Night	15% 6% 2 5% 3 3 3 3 4 6% 51%	2280
	21st to end	Night	18% 8% 2 5% 3 4 4 4 5% 6% 41%	2693
November	1st to 10th	Night	10% 6% 2 5% 4 4 3 3 4 6% 52%	2536
	11th to 20th	Night	14% 8% 2 6% 4 4 4 3 5% 6% 44%	2600
	21st to end	Night	18% 10% 4 7% 4 4 4 2 4 6% 37%	2600
December	1st to 10th	Night	13% 9% 4 7% 4 4 3 3 4 5% 45%	4476
	11th to 20th	Night	17% 10% 4 9% 5% 4 4 4 4 6% 33%	5199
	21st to end	Night	29% 17% 5% 9% 5% 4 3 3 3 4 18%	6996

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	61% 5% 8% 20% 7% 1	2576
	11th to 20th	Day	67% 4 11% 11% 6%	2530
	21st to end	Day	69% 4 8% 14% 4 1	2984
February	1st to 10th	Day	56% 5% 11% 17% 10% 1	1826
	11th to 20th	Day	53% 4 11% 21% 10% 1	1858
	21st to end	Day	54% 4 8% 22% 9% 3	1570
March	1st to 10th	Day	57% 4 7% 17% 13% 2	3120
	11th to 20th	Day	38% 5% 13% 26% 17% 1	3268
	21st to end	Day	52% 7% 12% 23% 5% 1	4165
April	1st to 10th	Day	45% 7% 12% 21% 14% 1	2280
	11th to 20th	Day	45% 5% 11% 25% 11% 4	2254
	21st to end	Day	49% 5% 12% 21% 11% 3	2332
May	1st to 10th	Day	46% 9% 14% 23% 7%	4120
	11th to 20th	Day	45% 7% 12% 26% 9%	4107
	21st to end	Day	34% 8% 13% 19% 22% 3	4837
June	1st to 10th	Day	35% 8% 13% 25% 15% 4	2660
	11th to 20th	Day	32% 7% 11% 23% 22% 5%	2660
	21st to end	Day	35% 8% 16% 21% 16% 4	2660
July	1st to 10th	Day	39% 6% 11% 28% 13% 2	4371
	11th to 20th	Day	31% 8% 15% 28% 17% 1	4365
	21st to end	Day	37% 7% 19% 21% 15% 2	4662
August	1st to 10th	Day	28% 6% 16% 34% 15% 1	4064
	11th to 20th	Day	35% 7% 15% 26% 16% 1	3765
	21st to end	Day	28% 6% 16% 31% 14% 4	4179
September	1st to 10th	Day	37% 5% 11% 24% 19% 4	2280
	11th to 20th	Day	32% 6% 11% 23% 24% 4	2146
	21st to end	Day	34% 5% 10% 25% 23% 3	2090
October	1st to 10th	Day	23% 4 8% 25% 37% 3	3451
	11th to 20th	Day	29% 3 7% 24% 34% 2	3140
	21st to end	Day	39% 3 8% 23% 25% 1	3116
November	1st to 10th	Day	34% 4 14% 25% 18% 5%	1762
	11th to 20th	Day	45% 4 10% 22% 15% 5%	1800
	21st to end	Day	50% 5% 9% 22% 14% 1	1800
December	1st to 10th	Day	44% 3 13% 29% 11%	2706
	11th to 20th	Day	58% 3 10% 23% 5% 1	3005
	21st to end	Day	74% 3 10% 10% 4	3982
January	1st to 10th	Night	58% 5% 11% 19% 8%	4513
	11th to 20th	Night	67% 4 8% 14% 7%	4440
	21st to end	Night	64% 3 8% 16% 7%	4679
February	1st to 10th	Night	55% 4 11% 18% 9% 2	2352
	11th to 20th	Night	48% 4 11% 22% 13% 2	2219
	21st to end	Night	51% 4 10% 21% 11% 3	1884
March	1st to 10th	Night	53% 5% 8% 22% 11% 1	3733
	11th to 20th	Night	35% 5% 10% 26% 21% 2	3719
	21st to end	Night	50% 7% 11% 25% 7% 1	3466
April	1st to 10th	Night	42% 7% 10% 24% 16% 2	1900
	11th to 20th	Night	42% 5% 9% 23% 17% 4	1875
	21st to end	Night	48% 7% 9% 20% 12% 3	1847
May	1st to 10th	Night	46% 9% 15% 22% 8% 1	2840
	11th to 20th	Night	42% 7% 12% 27% 11% 1	2787
	21st to end	Night	36% 8% 13% 20% 19% 4	2751
June	1st to 10th	Night	32% 6% 11% 27% 19% 5%	1520
	11th to 20th	Night	30% 6% 10% 26% 23% 5%	1520
	21st to end	Night	31% 7% 16% 22% 19% 5%	1520
July	1st to 10th	Night	35% 5% 12% 27% 17% 5%	2490
	11th to 20th	Night	22% 5% 14% 33% 24% 2	2482
	21st to end	Night	36% 5% 17% 21% 16% 3	2662
August	1st to 10th	Night	26% 6% 15% 35% 16% 1	2840
	11th to 20th	Night	32% 6% 13% 28% 20% 1	3130
	21st to end	Night	24% 6% 14% 32% 19% 4	3476
September	1st to 10th	Night	30% 5% 10% 27% 21% 7%	1900
	11th to 20th	Night	27% 5% 9% 27% 26% 5%	2014
	21st to end	Night	32% 7% 9% 24% 24% 4	2090
October	1st to 10th	Night	20% 4 6% 25% 43% 3	3506
	11th to 20th	Night	24% 3 7% 27% 35% 3	3779
	21st to end	Night	35% 4 8% 24% 24% 5%	4431
November	1st to 10th	Night	34% 5% 9% 26% 21% 5%	2536
	11th to 20th	Night	41% 4 10% 24% 19% 2	2600
	21st to end	Night	50% 4 9% 22% 14% 1	2600
December	1st to 10th	Night	43% 3 11% 28% 14% 1	4476
	11th to 20th	Night	53% 4 11% 20% 11%	5201
	21st to end	Night	71% 4 9% 11% 4 1	6996

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	20% 20% 34% 18% 7%	288
	11th to 20th	Day	23% 19% 37% 18% 4	270
	21st to end	Day	22% 15% 36% 21% 5%	297
February	1st to 10th	Day	26% 16% 32% 21% 5%	270
	11th to 20th	Day	22% 21% 35% 16% 3 3	270
	21st to end	Day	25% 15% 39% 18% 3	225
March	1st to 10th	Day	21% 21% 35% 19% 4	270
	11th to 20th	Day	25% 19% 37% 16% 4	298
	21st to end	Day	28% 14% 35% 16% 6% 1	506
April	1st to 10th	Day	19% 15% 32% 25% 7% 1	460
	11th to 20th	Day	19% 18% 28% 20% 13% 2	452
	21st to end	Day	25% 14% 36% 15% 8% 2	460
May	1st to 10th	Day	17% 13% 32% 24% 11% 2	463
	11th to 20th	Day	20% 7% 27% 27% 15% 5%	496
	21st to end	Day	10% 5% 31% 28% 17% 9%	734
June	1st to 10th	Day	10% 6% 24% 31% 22% 7%	680
	11th to 20th	Day	10% 3 25% 34% 21% 7%	680
	21st to end	Day	10% 6% 30% 28% 20% 7%	680
July	1st to 10th	Day	11% 3 15% 27% 26% 19%	671
	11th to 20th	Day	6% 3 17% 35% 26% 13%	668
	21st to end	Day	10% 2 15% 33% 31% 10%	739
August	1st to 10th	Day	8% 2 14% 29% 34% 12%	543
	11th to 20th	Day	12% 3 18% 29% 26% 12%	479
	21st to end	Day	6% 2 12% 31% 35% 14%	539
September	1st to 10th	Day	11% 4 16% 28% 32% 9%	490
	11th to 20th	Day	9% 2 12% 29% 32% 16%	490
	21st to end	Day	13% 7% 24% 24% 20% 13%	490
October	1st to 10th	Day	12% 4 25% 29% 22% 8%	474
	11th to 20th	Day	14% 15% 35% 21% 13% 1	300
	21st to end	Day	27% 15% 32% 20% 5% 1	330
November	1st to 10th	Day	11% 13% 31% 27% 13% 4	300
	11th to 20th	Day	19% 18% 32% 21% 9% 1	300
	21st to end	Day	23% 12% 34% 23% 6% 1	300
December	1st to 10th	Day	14% 19% 40% 19% 6% 2	300
	11th to 20th	Day	20% 14% 38% 20% 7% 1	300
	21st to end	Day	28% 18% 32% 17% 6%	330
January	1st to 10th	Night	20% 15% 38% 23% 4	981
	11th to 20th	Night	23% 17% 35% 22% 4	950
	21st to end	Night	23% 14% 36% 25% 3	1045
February	1st to 10th	Night	25% 12% 38% 23% 2	832
	11th to 20th	Night	18% 15% 38% 25% 3	743
	21st to end	Night	27% 12% 37% 22% 2	628
March	1st to 10th	Night	23% 13% 34% 26% 5%	760
	11th to 20th	Night	21% 11% 38% 24% 6%	746
	21st to end	Night	24% 10% 32% 28% 6%	627
April	1st to 10th	Night	18% 13% 35% 28% 6%	570
	11th to 20th	Night	21% 12% 32% 25% 11%	563
	21st to end	Night	22% 9% 38% 24% 7% 1	570
May	1st to 10th	Night	18% 7% 34% 33% 8%	570
	11th to 20th	Night	17% 5% 27% 34% 16% 1	561
	21st to end	Night	11% 5% 25% 34% 23% 2	617
June	1st to 10th	Night	11% 3 23% 41% 22%	570
	11th to 20th	Night	9% 2 23% 45% 21% 1	570
	21st to end	Night	8% 3 24% 40% 25% 1	570
July	1st to 10th	Night	10% 1 13% 33% 37% 6%	555
	11th to 20th	Night	5% 3 16% 43% 30% 4	552
	21st to end	Night	7% 1 13% 45% 31% 3	624
August	1st to 10th	Night	7% 3 11% 41% 34% 5%	567
	11th to 20th	Night	7% 1 13% 41% 34% 4	564
	21st to end	Night	8% 1 13% 35% 39% 4	627
September	1st to 10th	Night	13% 3 15% 35% 29% 5%	570
	11th to 20th	Night	7% 3 14% 39% 33% 4	684
	21st to end	Night	14% 5% 21% 31% 26% 4	760
October	1st to 10th	Night	11% 4 24% 38% 20% 4	760
	11th to 20th	Night	18% 12% 27% 28% 14% 1	760
	21st to end	Night	21% 12% 33% 27% 6%	836
November	1st to 10th	Night	13% 9% 39% 28% 11%	780
	11th to 20th	Night	19% 12% 32% 28% 8% 1	800
	21st to end	Night	24% 13% 31% 26% 6%	800
December	1st to 10th	Night	22% 10% 39% 23% 5% 1	935
	11th to 20th	Night	23% 9% 35% 27% 6%	1000
	21st to end	Night	29% 16% 31% 21% 3	1100

Page generated at 2025-01-04 02:24:04. Version ac07

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