Sassafras Ridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sassafras Ridge clear sky chart from 2005-11-06 to 2024-11-04.

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% 9% 3 8% 6% 5% 5% 4 6% 7% 33%	101000
	Night	13% 10% 4 8% 5% 4 5% 4 5% 7% 37%	97988
Transparency	Day	44% 8% 11% 18% 14% 4	104794
	Night	42% 7% 12% 19% 15% 5%	102332
Seeing	Day	22% 13% 23% 21% 14% 8%	14862
	Night	19% 11% 19% 27% 20% 4	24879

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	16% 12% 4 7% 4 4 6% 5% 5% 6% 30%	2836
	11th to 20th	Day	14% 11% 5% 14% 4 4 4 3 4 5% 32%	2840
	21st to end	Day	17% 15% 7% 6% 4 3 3 3 4 5% 33%	3133
February	1st to 10th	Day	17% 12% 4 8% 5% 4 5% 3 4 4 33%	1900
	11th to 20th	Day	19% 12% 4 10% 6% 3 3 3 4 5% 32%	1848
	21st to end	Day	20% 12% 2 9% 5% 4 3 3 5% 4 33%	1570
March	1st to 10th	Day	22% 11% 3 6% 4 4 3 3 5% 6% 32%	3230
	11th to 20th	Day	13% 8% 2 6% 5% 4 4 3 4 5% 46%	3480
	21st to end	Day	16% 12% 3 7% 5% 4 4 3 4 5% 36%	3815
April	1st to 10th	Day	11% 10% 3 7% 5% 5% 5% 5% 6% 7% 37%	2147
	11th to 20th	Day	15% 8% 2 7% 4 4 4 4 4 7% 41%	2259
	21st to end	Day	14% 9% 3 7% 5% 4 4 3 6% 6% 39%	2470
May	1st to 10th	Day	15% 9% 3 9% 5% 5% 5% 4 7% 5% 31%	4082
	11th to 20th	Day	17% 11% 4 9% 6% 5% 5% 4 5% 6% 26%	4081
	21st to end	Day	10% 7% 3 8% 6% 6% 6% 5% 8% 10% 32%	4476
June	1st to 10th	Day	11% 8% 3 8% 6% 6% 6% 6% 7% 8% 29%	2470
	11th to 20th	Day	6% 6% 3 9% 7% 7% 6% 6% 7% 10% 32%	2470
	21st to end	Day	10% 8% 3 7% 7% 6% 6% 5% 7% 11% 30%	2470
July	1st to 10th	Day	7% 7% 3 9% 8% 8% 9% 7% 8% 10% 24%	4120
	11th to 20th	Day	11% 7% 3 10% 7% 7% 7% 5% 7% 7% 27%	4120
	21st to end	Day	14% 12% 6% 15% 9% 8% 7% 4 6% 7% 15%	4466
August	1st to 10th	Day	7% 6% 3 9% 6% 7% 7% 6% 8% 11% 29%	4104
	11th to 20th	Day	8% 5% 3 8% 7% 6% 7% 6% 9% 11% 31%	3920
	21st to end	Day	8% 6% 3 8% 6% 7% 7% 5% 7% 7% 36%	4180
September	1st to 10th	Day	12% 8% 3 9% 6% 6% 6% 5% 7% 7% 32%	2100
	11th to 20th	Day	15% 8% 3 8% 5% 5% 6% 4 6% 8% 31%	2090
	21st to end	Day	15% 7% 2 7% 5% 4 5% 4 6% 6% 39%	2090
October	1st to 10th	Day	11% 6% 2 6% 4 5% 5% 4 5% 5% 47%	2090
	11th to 20th	Day	12% 7% 2 6% 3 3 4 2 5% 6% 50%	1952
	21st to end	Day	13% 7% 2 5% 4 4 4 3 4 6% 49%	2085
November	1st to 10th	Day	11% 7% 1 5% 3 3 4 3 3 6% 53%	1699
	11th to 20th	Day	12% 8% 3 6% 4 4 4 4 5% 5% 46%	1710
	21st to end	Day	13% 10% 2 7% 4 3 4 3 5% 6% 42%	1710
December	1st to 10th	Day	19% 12% 5% 8% 4 6% 5% 3 3 5% 31%	1710
	11th to 20th	Day	15% 10% 4 8% 5% 4 5% 3 5% 5% 36%	2153
	21st to end	Day	13% 12% 6% 10% 5% 3 5% 3 5% 6% 32%	3124
January	1st to 10th	Night	15% 16% 5% 8% 4 4 4 3 4 6% 32%	4109
	11th to 20th	Night	18% 11% 4 8% 4 4 4 3 4 6% 31%	4120
	21st to end	Night	19% 17% 5% 8% 3 3 3 2 3 3 33%	4521
February	1st to 10th	Night	14% 11% 4 9% 6% 4 5% 3 4 5% 36%	2280
	11th to 20th	Night	18% 13% 5% 10% 5% 4 3 3 3 4 33%	2218
	21st to end	Night	19% 14% 3 10% 4 4 4 3 4 4 30%	1884
March	1st to 10th	Night	19% 14% 4 8% 5% 6% 5% 3 5% 5% 27%	3621
	11th to 20th	Night	12% 8% 3 7% 4 4 4 3 5% 7% 43%	3480
	21st to end	Night	14% 11% 4 8% 5% 4 4 4 4 5% 38%	3817
April	1st to 10th	Night	13% 10% 3 6% 5% 4 4 3 5% 6% 41%	2048
	11th to 20th	Night	12% 10% 3 6% 4 3 4 4 5% 6% 43%	1870
	21st to end	Night	13% 8% 2 5% 5% 4 3 4 5% 7% 43%	1710
May	1st to 10th	Night	12% 9% 4 10% 6% 5% 6% 4 5% 7% 32%	2813
	11th to 20th	Night	17% 11% 4 8% 5% 4 5% 3 5% 7% 32%	2812
	21st to end	Night	7% 8% 3 8% 5% 5% 5% 5% 7% 11% 37%	3079
June	1st to 10th	Night	8% 7% 2 7% 7% 5% 6% 5% 8% 10% 34%	1710
	11th to 20th	Night	5% 4 2 5% 5% 5% 6% 5% 10% 12% 41%	1710
	21st to end	Night	8% 6% 3 7% 5% 6% 6% 5% 6% 9% 38%	1710
July	1st to 10th	Night	8% 7% 3 9% 6% 5% 6% 5% 8% 9% 32%	2840
	11th to 20th	Night	8% 5% 3 7% 5% 5% 6% 4 9% 10% 38%	2840
	21st to end	Night	11% 10% 4 12% 8% 6% 7% 5% 8% 9% 20%	3087
August	1st to 10th	Night	6% 6% 2 8% 6% 5% 6% 6% 8% 12% 37%	2825
	11th to 20th	Night	7% 6% 4 9% 6% 6% 5% 4 6% 8% 39%	2904
	21st to end	Night	6% 5% 2 6% 5% 4 5% 4 7% 9% 46%	3476
September	1st to 10th	Night	11% 7% 3 7% 6% 5% 5% 4 7% 7% 39%	2061
	11th to 20th	Night	11% 8% 3 8% 6% 5% 5% 4 6% 7% 38%	2090
	21st to end	Night	12% 7% 3 7% 4 5% 4 4 4 6% 45%	2090
October	1st to 10th	Night	11% 6% 2 5% 4 3 3 3 4 5% 53%	2090
	11th to 20th	Night	13% 8% 2 5% 4 3 3 3 4 5% 49%	2226
	21st to end	Night	11% 7% 3 6% 4 3 3 3 4 5% 50%	2511
November	1st to 10th	Night	11% 8% 2 5% 4 4 3 3 5% 5% 49%	2452
	11th to 20th	Night	13% 10% 3 7% 4 3 4 3 5% 5% 46%	2470
	21st to end	Night	13% 10% 3 6% 4 4 4 4 4 6% 41%	2470
December	1st to 10th	Night	17% 12% 5% 10% 5% 4 5% 3 4 5% 29%	2470
	11th to 20th	Night	13% 13% 5% 9% 4 5% 4 3 4 5% 36%	3042
	21st to end	Night	13% 14% 7% 11% 6% 5% 5% 4 5% 6% 24%	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	48% 5% 8% 13% 22% 5%	2837
	11th to 20th	Day	51% 5% 7% 11% 20% 6%	2840
	21st to end	Day	52% 4 7% 15% 20% 4	3133
February	1st to 10th	Day	52% 5% 6% 16% 16% 4	1900
	11th to 20th	Day	53% 5% 5% 15% 17% 5%	1858
	21st to end	Day	53% 4 7% 13% 18% 6%	1570
March	1st to 10th	Day	50% 4 8% 16% 14% 8%	3230
	11th to 20th	Day	39% 5% 8% 20% 19% 9%	3480
	21st to end	Day	48% 5% 8% 25% 10% 4	3815
April	1st to 10th	Day	42% 6% 11% 21% 17% 2	2147
	11th to 20th	Day	42% 6% 9% 18% 21% 4	2259
	21st to end	Day	43% 7% 10% 25% 14% 2	2470
May	1st to 10th	Day	48% 9% 11% 21% 10% 1	4120
	11th to 20th	Day	53% 9% 9% 21% 7% 1	4085
	21st to end	Day	40% 11% 13% 21% 13% 1	4489
June	1st to 10th	Day	46% 11% 14% 21% 7% 1	2470
	11th to 20th	Day	41% 11% 16% 20% 10% 1	2470
	21st to end	Day	43% 12% 15% 16% 11% 3	2470
July	1st to 10th	Day	45% 16% 17% 16% 6% 1	4055
	11th to 20th	Day	48% 14% 17% 15% 6% 1	4051
	21st to end	Day	66% 10% 11% 10% 4	4324
August	1st to 10th	Day	41% 11% 18% 23% 7%	4091
	11th to 20th	Day	38% 12% 22% 15% 11% 2	3959
	21st to end	Day	40% 11% 12% 27% 9% 1	4179
September	1st to 10th	Day	46% 9% 11% 15% 16% 3	2100
	11th to 20th	Day	48% 8% 9% 18% 17% 1	2090
	21st to end	Day	42% 7% 12% 17% 17% 5%	2090
October	1st to 10th	Day	27% 6% 8% 17% 29% 13%	3480
	11th to 20th	Day	24% 3 5% 19% 25% 24%	3218
	21st to end	Day	28% 5% 5% 26% 22% 13%	3411
November	1st to 10th	Day	34% 4 7% 17% 28% 10%	1699
	11th to 20th	Day	38% 5% 5% 19% 25% 9%	1710
	21st to end	Day	41% 4 8% 17% 25% 5%	1710
December	1st to 10th	Day	54% 6% 5% 16% 15% 4	1710
	11th to 20th	Day	47% 4 9% 12% 21% 6%	2150
	21st to end	Day	52% 3 10% 18% 14% 3	3124
January	1st to 10th	Night	50% 5% 8% 12% 20% 6%	4109
	11th to 20th	Night	51% 4 6% 10% 19% 9%	4120
	21st to end	Night	56% 3 6% 10% 19% 6%	4521
February	1st to 10th	Night	49% 4 8% 15% 19% 4	2280
	11th to 20th	Night	54% 5% 5% 16% 15% 4	2219
	21st to end	Night	55% 5% 7% 14% 14% 5%	1884
March	1st to 10th	Night	55% 8% 8% 11% 14% 4	3621
	11th to 20th	Night	37% 6% 10% 22% 17% 8%	3480
	21st to end	Night	47% 6% 9% 21% 14% 3	3817
April	1st to 10th	Night	39% 6% 12% 21% 18% 3	2048
	11th to 20th	Night	39% 5% 11% 20% 21% 5%	1870
	21st to end	Night	38% 7% 12% 29% 14% 1	1710
May	1st to 10th	Night	45% 10% 14% 21% 9% 1	2840
	11th to 20th	Night	47% 10% 15% 20% 8%	2813
	21st to end	Night	35% 12% 17% 25% 10% 1	3087
June	1st to 10th	Night	41% 11% 17% 22% 8% 1	1710
	11th to 20th	Night	30% 12% 22% 27% 8% 1	1710
	21st to end	Night	37% 10% 18% 21% 10% 3	1710
July	1st to 10th	Night	42% 13% 22% 19% 5%	2795
	11th to 20th	Night	34% 13% 27% 20% 5% 2	2786
	21st to end	Night	56% 13% 15% 11% 4	2988
August	1st to 10th	Night	35% 12% 22% 25% 6%	2814
	11th to 20th	Night	33% 11% 26% 19% 10% 1	2931
	21st to end	Night	29% 11% 19% 32% 7% 1	3476
September	1st to 10th	Night	40% 10% 15% 17% 15% 4	2061
	11th to 20th	Night	42% 10% 12% 19% 16%	2090
	21st to end	Night	39% 7% 11% 21% 19% 4	2090
October	1st to 10th	Night	21% 5% 12% 24% 25% 13%	3480
	11th to 20th	Night	24% 4 7% 19% 26% 20%	3699
	21st to end	Night	29% 5% 5% 24% 24% 13%	4135
November	1st to 10th	Night	36% 5% 7% 20% 24% 9%	2452
	11th to 20th	Night	38% 5% 5% 19% 23% 9%	2470
	21st to end	Night	43% 4 6% 21% 21% 6%	2470
December	1st to 10th	Night	54% 6% 7% 15% 13% 5%	2470
	11th to 20th	Night	48% 4 9% 12% 21% 6%	3044
	21st to end	Night	56% 5% 10% 15% 13% 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	34% 24% 31% 9% 2	270
	11th to 20th	Day	36% 28% 20% 12% 4	270
	21st to end	Day	30% 32% 28% 7% 3	297
February	1st to 10th	Day	34% 23% 32% 10% 1	270
	11th to 20th	Day	48% 19% 28% 4 1	270
	21st to end	Day	45% 26% 22% 6%	225
March	1st to 10th	Day	32% 19% 31% 13% 5%	328
	11th to 20th	Day	27% 26% 25% 16% 5% 1	460
	21st to end	Day	29% 22% 28% 16% 4 1	506
April	1st to 10th	Day	27% 17% 27% 19% 9% 1	460
	11th to 20th	Day	23% 21% 25% 18% 10% 3	452
	21st to end	Day	25% 16% 26% 18% 12% 3	460
May	1st to 10th	Day	22% 17% 30% 17% 10% 5%	463
	11th to 20th	Day	19% 10% 28% 22% 14% 7%	487
	21st to end	Day	16% 10% 21% 28% 15% 11%	529
June	1st to 10th	Day	18% 8% 21% 26% 18% 10%	490
	11th to 20th	Day	10% 5% 20% 28% 22% 16%	490
	21st to end	Day	13% 6% 25% 27% 16% 13%	490
July	1st to 10th	Day	13% 5% 16% 25% 25% 17%	485
	11th to 20th	Day	13% 4 16% 25% 24% 19%	484
	21st to end	Day	13% 4 16% 24% 24% 20%	532
August	1st to 10th	Day	17% 6% 17% 20% 22% 18%	486
	11th to 20th	Day	16% 4 16% 28% 24% 12%	479
	21st to end	Day	17% 3 11% 22% 27% 20%	539
September	1st to 10th	Day	11% 5% 14% 28% 29% 13%	490
	11th to 20th	Day	18% 6% 14% 24% 26% 12%	490
	21st to end	Day	20% 8% 15% 27% 23% 7%	490
October	1st to 10th	Day	17% 7% 22% 28% 19% 8%	490
	11th to 20th	Day	19% 12% 25% 23% 19% 3	490
	21st to end	Day	21% 11% 26% 24% 14% 3	534
November	1st to 10th	Day	20% 15% 30% 24% 9% 1	279
	11th to 20th	Day	25% 18% 31% 21% 5%	270
	21st to end	Day	20% 25% 34% 13% 7% 1	270
December	1st to 10th	Day	34% 19% 29% 14% 4	270
	11th to 20th	Day	27% 18% 33% 19% 4 1	270
	21st to end	Day	34% 19% 33% 10% 3	297
January	1st to 10th	Night	28% 18% 25% 24% 5%	760
	11th to 20th	Night	30% 20% 24% 21% 5%	760
	21st to end	Night	22% 20% 30% 25% 2	836
February	1st to 10th	Night	22% 17% 29% 28% 5%	760
	11th to 20th	Night	31% 19% 29% 20% 2	743
	21st to end	Night	32% 20% 28% 16% 4	628
March	1st to 10th	Night	21% 21% 30% 24% 5%	760
	11th to 20th	Night	23% 18% 27% 22% 8% 1	760
	21st to end	Night	24% 16% 29% 23% 7%	836
April	1st to 10th	Night	20% 18% 26% 25% 10% 1	718
	11th to 20th	Night	21% 14% 21% 28% 13% 2	563
	21st to end	Night	16% 11% 25% 32% 15% 1	570
May	1st to 10th	Night	16% 11% 23% 28% 20% 2	570
	11th to 20th	Night	16% 7% 18% 32% 24% 3	561
	21st to end	Night	14% 4 13% 32% 30% 7%	617
June	1st to 10th	Night	14% 2 13% 32% 33% 6%	570
	11th to 20th	Night	8% 3 10% 31% 36% 12%	570
	21st to end	Night	12% 3 10% 31% 37% 8%	570
July	1st to 10th	Night	13% 3 5% 23% 45% 11%	555
	11th to 20th	Night	11% 2 5% 24% 43% 15%	552
	21st to end	Night	10% 4 4 24% 44% 14%	624
August	1st to 10th	Night	12% 4 5% 24% 44% 11%	567
	11th to 20th	Night	13% 4 7% 29% 38% 10%	564
	21st to end	Night	14% 2 7% 19% 45% 13%	627
September	1st to 10th	Night	13% 3 10% 25% 38% 10%	731
	11th to 20th	Night	16% 4 9% 28% 36% 6%	760
	21st to end	Night	16% 5% 13% 27% 35% 4	760
October	1st to 10th	Night	15% 7% 15% 27% 29% 8%	760
	11th to 20th	Night	17% 9% 22% 28% 21% 3	760
	21st to end	Night	17% 12% 20% 33% 16% 3	836
November	1st to 10th	Night	17% 9% 18% 31% 21% 4	755
	11th to 20th	Night	19% 14% 21% 31% 12% 2	760
	21st to end	Night	22% 13% 22% 28% 14% 1	760
December	1st to 10th	Night	27% 16% 22% 27% 8%	760
	11th to 20th	Night	25% 13% 24% 30% 8% 1	760
	21st to end	Night	28% 13% 24% 29% 6%	836

Page generated at 2024-11-01 22:47:36. Version ac07

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