Redcliffe Plantation State Historic Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Redcliffe Plantation State Historic Site clear sky chart from 2005-11-06 to 2024-11-11.

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	12% 6% 2 6% 4 5% 5% 4 6% 8% 42%	101167
	Night	13% 6% 2 6% 4 4 5% 4 6% 8% 43%	97944
Transparency	Day	20% 48% 7% 11% 10% 4	104909
	Night	20% 48% 6% 10% 10% 5%	102341
Seeing	Day	14% 8% 21% 24% 21% 12%	15275
	Night	14% 6% 22% 32% 22% 3	25319

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% 6% 2 5% 3 4 4 3 6% 7% 45%	2836
	11th to 20th	Day	13% 6% 1 4 3 4 3 3 4 6% 52%	2840
	21st to end	Day	17% 9% 3 5% 4 4 3 2 4 5% 44%	3124
February	1st to 10th	Day	15% 7% 3 6% 4 4 4 4 6% 7% 40%	1807
	11th to 20th	Day	19% 7% 2 5% 3 2 3 3 4 6% 45%	1848
	21st to end	Day	18% 6% 2 5% 4 4 4 4 5% 5% 43%	1585
March	1st to 10th	Day	21% 9% 3 7% 3 3 3 3 4 5% 36%	3435
	11th to 20th	Day	9% 5% 2 5% 4 4 4 4 5% 7% 53%	3480
	21st to end	Day	19% 7% 3 5% 4 4 3 3 4 6% 42%	3815
April	1st to 10th	Day	9% 6% 2 5% 4 4 4 3 5% 7% 51%	2090
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 6% 8% 47%	2168
	21st to end	Day	7% 4 1 4 4 4 4 4 6% 9% 53%	2455
May	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 4 7% 9% 43%	4082
	11th to 20th	Day	16% 7% 3 7% 4 5% 4 3 5% 7% 39%	4081
	21st to end	Day	7% 4 2 5% 5% 5% 5% 4 7% 10% 47%	4476
June	1st to 10th	Day	10% 6% 3 7% 5% 6% 5% 5% 7% 10% 36%	2470
	11th to 20th	Day	6% 4 2 4 4 5% 7% 6% 7% 10% 43%	2470
	21st to end	Day	6% 5% 2 6% 6% 6% 6% 6% 9% 11% 37%	2470
July	1st to 10th	Day	13% 7% 3 7% 6% 6% 6% 5% 9% 10% 28%	4120
	11th to 20th	Day	5% 4 2 7% 6% 7% 8% 6% 10% 13% 32%	4120
	21st to end	Day	9% 8% 3 9% 6% 7% 8% 6% 10% 13% 22%	4466
August	1st to 10th	Day	18% 6% 3 7% 6% 6% 6% 6% 8% 10% 25%	4104
	11th to 20th	Day	8% 5% 2 6% 5% 6% 6% 5% 8% 11% 37%	4044
	21st to end	Day	7% 5% 2 5% 5% 4 5% 4 7% 11% 45%	4074
September	1st to 10th	Day	7% 5% 2 7% 6% 6% 6% 5% 7% 9% 39%	2090
	11th to 20th	Day	14% 5% 3 6% 5% 4 5% 3 6% 7% 41%	2090
	21st to end	Day	15% 6% 2 7% 4 4 4 4 4 6% 42%	2090
October	1st to 10th	Day	11% 6% 2 7% 4 4 4 3 4 5% 51%	2038
	11th to 20th	Day	11% 4 1 4 3 3 2 3 4 6% 59%	1900
	21st to end	Day	11% 4 2 5% 3 4 3 3 4 4 57%	2090
November	1st to 10th	Day	13% 6% 2 5% 4 3 3 3 4 5% 51%	1957
	11th to 20th	Day	14% 7% 2 3 3 2 3 2 4 5% 55%	1755
	21st to end	Day	14% 6% 1 5% 5% 4 3 3 4 6% 48%	1710
December	1st to 10th	Day	18% 6% 2 5% 4 4 4 3 5% 7% 40%	1710
	11th to 20th	Day	16% 5% 2 4 3 3 3 3 4 7% 48%	2153
	21st to end	Day	19% 8% 2 6% 3 4 3 3 5% 5% 43%	3124
January	1st to 10th	Night	17% 7% 2 4 3 3 4 4 5% 7% 45%	4109
	11th to 20th	Night	10% 6% 2 5% 4 4 5% 4 6% 8% 46%	4120
	21st to end	Night	17% 9% 3 6% 4 3 4 3 3 4 44%	4532
February	1st to 10th	Night	15% 7% 2 5% 4 4 4 3 5% 7% 44%	2371
	11th to 20th	Night	18% 7% 2 5% 4 4 3 2 4 5% 46%	2218
	21st to end	Night	13% 7% 3 5% 4 4 5% 3 5% 7% 44%	1867
March	1st to 10th	Night	22% 9% 3 6% 4 4 3 3 5% 5% 36%	3418
	11th to 20th	Night	12% 4 2 4 3 3 4 4 6% 7% 52%	3480
	21st to end	Night	18% 5% 2 5% 4 3 4 3 6% 7% 42%	3817
April	1st to 10th	Night	11% 4 2 5% 4 5% 5% 3 5% 7% 50%	2090
	11th to 20th	Night	12% 4 2 5% 3 4 4 3 5% 9% 50%	1959
	21st to end	Night	8% 4 1 4 5% 4 4 4 5% 7% 54%	1740
May	1st to 10th	Night	9% 6% 3 6% 5% 4 5% 3 7% 9% 43%	2813
	11th to 20th	Night	13% 6% 2 6% 5% 4 4 3 6% 8% 43%	2812
	21st to end	Night	6% 4 1 5% 4 4 5% 4 7% 8% 52%	3079
June	1st to 10th	Night	10% 7% 3 6% 5% 6% 6% 6% 8% 10% 33%	1710
	11th to 20th	Night	7% 5% 2 6% 6% 5% 6% 4 7% 11% 42%	1710
	21st to end	Night	7% 4 2 6% 6% 6% 6% 6% 10% 14% 34%	1710
July	1st to 10th	Night	14% 8% 3 8% 6% 6% 6% 5% 7% 9% 28%	2840
	11th to 20th	Night	6% 6% 3 8% 6% 6% 8% 6% 10% 13% 29%	2840
	21st to end	Night	11% 8% 3 9% 6% 6% 8% 6% 9% 11% 23%	3087
August	1st to 10th	Night	18% 6% 3 8% 6% 6% 6% 6% 9% 11% 21%	2825
	11th to 20th	Night	10% 5% 2 7% 5% 5% 6% 5% 8% 10% 36%	2785
	21st to end	Night	6% 5% 2 5% 4 5% 4 4 6% 12% 48%	3528
September	1st to 10th	Night	9% 6% 2 7% 5% 5% 6% 5% 8% 10% 38%	2090
	11th to 20th	Night	11% 8% 3 7% 6% 5% 6% 4 5% 6% 41%	2090
	21st to end	Night	14% 6% 2 6% 5% 4 5% 4 6% 7% 42%	2090
October	1st to 10th	Night	13% 5% 2 6% 4 4 3 3 4 6% 51%	2142
	11th to 20th	Night	12% 4 1 4 3 2 3 2 4 4 60%	2280
	21st to end	Night	10% 4 1 5% 3 4 3 3 4 5% 58%	2508
November	1st to 10th	Night	12% 5% 2 4 3 4 3 3 5% 4 54%	2341
	11th to 20th	Night	15% 6% 2 4 3 3 3 2 4 5% 52%	2429
	21st to end	Night	14% 5% 1 5% 3 3 4 4 5% 7% 49%	2470
December	1st to 10th	Night	16% 5% 2 5% 4 4 4 4 5% 7% 45%	2470
	11th to 20th	Night	18% 6% 2 4 3 3 3 2 4 4 52%	3042
	21st to end	Night	19% 8% 2 6% 4 3 5% 3 5% 6% 39%	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	23% 38% 5% 13% 13% 7%	2837
	11th to 20th	Day	19% 37% 4 11% 20% 9%	2840
	21st to end	Day	26% 40% 2 11% 15% 6%	3124
February	1st to 10th	Day	16% 65% 4 8% 5% 2	1807
	11th to 20th	Day	16% 64% 3 7% 9% 2	1858
	21st to end	Day	18% 64% 3 4 6% 5%	1585
March	1st to 10th	Day	37% 43% 5% 6% 6% 4	3435
	11th to 20th	Day	15% 41% 5% 10% 20% 9%	3480
	21st to end	Day	28% 40% 3 11% 14% 4	3815
April	1st to 10th	Day	13% 65% 4 7% 8% 3	2090
	11th to 20th	Day	16% 66% 5% 6% 5% 3	2168
	21st to end	Day	11% 66% 4 9% 8% 2	2455
May	1st to 10th	Day	23% 44% 8% 17% 7% 1	4120
	11th to 20th	Day	29% 41% 6% 15% 9% 1	4085
	21st to end	Day	14% 43% 12% 11% 17% 2	4489
June	1st to 10th	Day	15% 67% 7% 6% 4 1	2470
	11th to 20th	Day	9% 67% 9% 9% 6%	2470
	21st to end	Day	12% 67% 9% 8% 4	2470
July	1st to 10th	Day	30% 41% 14% 12% 2	4055
	11th to 20th	Day	21% 45% 19% 14% 1	4051
	21st to end	Day	33% 45% 14% 6% 3	4324
August	1st to 10th	Day	37% 41% 13% 8%	4091
	11th to 20th	Day	19% 42% 11% 17% 11% 1	4083
	21st to end	Day	11% 39% 10% 28% 11% 1	4074
September	1st to 10th	Day	13% 64% 8% 7% 7% 2	2090
	11th to 20th	Day	17% 62% 5% 8% 6% 2	2090
	21st to end	Day	18% 61% 7% 7% 6% 1	2090
October	1st to 10th	Day	20% 37% 5% 9% 23% 7%	3389
	11th to 20th	Day	6% 36% 3 8% 20% 27%	3140
	21st to end	Day	12% 37% 3 15% 24% 9%	3428
November	1st to 10th	Day	20% 56% 4 6% 10% 4	1957
	11th to 20th	Day	17% 59% 3 8% 9% 4	1755
	21st to end	Day	14% 60% 4 10% 9% 4	1710
December	1st to 10th	Day	21% 60% 4 6% 7% 2	1710
	11th to 20th	Day	17% 48% 2 10% 18% 6%	2150
	21st to end	Day	29% 38% 5% 12% 15% 1	3124
January	1st to 10th	Night	24% 39% 5% 9% 15% 7%	4109
	11th to 20th	Night	20% 39% 5% 14% 17% 5%	4120
	21st to end	Night	27% 41% 2 6% 17% 6%	4532
February	1st to 10th	Night	13% 65% 4 7% 8% 3	2371
	11th to 20th	Night	18% 64% 2 7% 7% 2	2219
	21st to end	Night	17% 65% 3 5% 5% 5%	1867
March	1st to 10th	Night	35% 43% 8% 8% 4 2	3418
	11th to 20th	Night	17% 40% 4 8% 19% 13%	3480
	21st to end	Night	26% 41% 4 10% 11% 7%	3817
April	1st to 10th	Night	14% 65% 4 6% 7% 4	2090
	11th to 20th	Night	14% 66% 4 8% 5% 3	1959
	21st to end	Night	10% 66% 4 10% 7% 2	1740
May	1st to 10th	Night	22% 46% 10% 14% 7% 1	2840
	11th to 20th	Night	24% 42% 9% 15% 10% 1	2813
	21st to end	Night	13% 44% 10% 15% 16% 2	3087
June	1st to 10th	Night	17% 67% 7% 5% 3 1	1710
	11th to 20th	Night	12% 66% 8% 8% 6% 1	1710
	21st to end	Night	11% 68% 9% 8% 4	1710
July	1st to 10th	Night	33% 42% 15% 9% 1	2795
	11th to 20th	Night	28% 44% 16% 11% 1	2786
	21st to end	Night	37% 44% 12% 5% 2	2988
August	1st to 10th	Night	39% 43% 12% 6% 1	2814
	11th to 20th	Night	21% 43% 15% 15% 6% 1	2812
	21st to end	Night	10% 39% 12% 28% 10% 1	3528
September	1st to 10th	Night	14% 63% 7% 7% 5% 2	2090
	11th to 20th	Night	19% 61% 5% 7% 6% 1	2090
	21st to end	Night	16% 62% 8% 9% 5% 1	2090
October	1st to 10th	Night	22% 38% 6% 9% 19% 6%	3571
	11th to 20th	Night	6% 36% 2 8% 14% 33%	3779
	21st to end	Night	11% 36% 3 12% 23% 14%	4120
November	1st to 10th	Night	19% 56% 4 6% 11% 4	2341
	11th to 20th	Night	16% 59% 3 6% 9% 6%	2429
	21st to end	Night	13% 60% 4 8% 11% 4	2470
December	1st to 10th	Night	20% 60% 4 7% 7% 2	2470
	11th to 20th	Night	17% 49% 2 9% 18% 6%	3044
	21st to end	Night	30% 39% 4 12% 14% 1	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	19% 19% 42% 16% 4	270
	11th to 20th	Day	20% 17% 33% 24% 6%	270
	21st to end	Day	22% 23% 36% 15% 4 1	297
February	1st to 10th	Day	20% 16% 40% 20% 4	270
	11th to 20th	Day	27% 19% 36% 16% 2	270
	21st to end	Day	24% 21% 34% 15% 5%	240
March	1st to 10th	Day	20% 12% 29% 27% 11%	460
	11th to 20th	Day	14% 13% 40% 25% 7% 1	460
	21st to end	Day	18% 14% 37% 21% 9% 1	506
April	1st to 10th	Day	13% 17% 30% 25% 13% 1	460
	11th to 20th	Day	14% 11% 25% 26% 18% 6%	452
	21st to end	Day	10% 11% 22% 28% 21% 8%	460
May	1st to 10th	Day	8% 11% 25% 29% 19% 8%	463
	11th to 20th	Day	14% 2 17% 28% 24% 14%	487
	21st to end	Day	14% 4 12% 26% 25% 19%	529
June	1st to 10th	Day	12% 3 13% 26% 30% 17%	490
	11th to 20th	Day	8% 3 14% 23% 24% 28%	490
	21st to end	Day	8% 2 9% 31% 27% 23%	490
July	1st to 10th	Day	9% 2 7% 18% 31% 33%	485
	11th to 20th	Day	9% 2 4 17% 40% 29%	484
	21st to end	Day	8% 1 7% 23% 36% 25%	532
August	1st to 10th	Day	11% 2 11% 19% 34% 22%	486
	11th to 20th	Day	12% 3 5% 18% 37% 25%	479
	21st to end	Day	13% 2 8% 22% 29% 26%	539
September	1st to 10th	Day	10% 4 8% 28% 29% 20%	490
	11th to 20th	Day	18% 3 12% 24% 30% 13%	490
	21st to end	Day	18% 2 16% 23% 26% 15%	490
October	1st to 10th	Day	14% 3 20% 30% 23% 9%	490
	11th to 20th	Day	10% 4 22% 31% 22% 11%	490
	21st to end	Day	14% 6% 22% 29% 24% 5%	539
November	1st to 10th	Day	18% 6% 26% 27% 19% 5%	495
	11th to 20th	Day	17% 12% 36% 23% 10% 2	315
	21st to end	Day	13% 13% 31% 27% 13% 2	270
December	1st to 10th	Day	22% 13% 33% 24% 8% 1	270
	11th to 20th	Day	21% 13% 37% 18% 10% 1	270
	21st to end	Day	29% 13% 31% 16% 8% 2	297
January	1st to 10th	Night	20% 12% 33% 29% 6%	760
	11th to 20th	Night	17% 10% 33% 32% 8%	760
	21st to end	Night	20% 9% 39% 28% 4	836
February	1st to 10th	Night	17% 10% 31% 33% 8%	760
	11th to 20th	Night	21% 11% 34% 31% 3	743
	21st to end	Night	18% 13% 36% 29% 4	628
March	1st to 10th	Night	15% 9% 32% 36% 7%	760
	11th to 20th	Night	15% 10% 34% 32% 8% 1	760
	21st to end	Night	15% 11% 35% 30% 10%	836
April	1st to 10th	Night	11% 11% 32% 33% 13%	760
	11th to 20th	Night	15% 9% 26% 34% 16%	751
	21st to end	Night	9% 5% 24% 43% 18% 1	600
May	1st to 10th	Night	9% 5% 26% 40% 18% 1	570
	11th to 20th	Night	10% 3 23% 39% 22% 4	561
	21st to end	Night	11% 2 9% 37% 36% 5%	617
June	1st to 10th	Night	14% 2 11% 36% 32% 4	570
	11th to 20th	Night	7% 4 11% 31% 36% 11%	570
	21st to end	Night	7% 2 8% 31% 45% 6%	570
July	1st to 10th	Night	10% 3 6% 26% 47% 7%	555
	11th to 20th	Night	9% 1 4 26% 52% 8%	552
	21st to end	Night	8% 2 8% 29% 46% 7%	624
August	1st to 10th	Night	10% 2 5% 27% 46% 9%	567
	11th to 20th	Night	14% 2 3 30% 43% 8%	564
	21st to end	Night	13% 1 10% 26% 42% 8%	750
September	1st to 10th	Night	10% 2 9% 30% 42% 7%	760
	11th to 20th	Night	15% 3 10% 30% 38% 4	760
	21st to end	Night	17% 2 13% 31% 33% 5%	760
October	1st to 10th	Night	15% 3 15% 35% 27% 6%	760
	11th to 20th	Night	14% 4 19% 36% 24% 3	760
	21st to end	Night	11% 5% 22% 34% 25% 2	836
November	1st to 10th	Night	14% 6% 22% 33% 21% 4	780
	11th to 20th	Night	17% 8% 26% 33% 15% 1	763
	21st to end	Night	15% 7% 28% 33% 16% 1	760
December	1st to 10th	Night	18% 7% 28% 34% 11% 1	760
	11th to 20th	Night	19% 6% 28% 33% 13% 1	760
	21st to end	Night	24% 10% 26% 30% 9%	836

Page generated at 2024-11-08 06:44:45. Version ac07

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