Lake Sylvia Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Sylvia Recreation Area clear sky chart from 2005-11-06 to 2025-01-22.

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%	104415
	Night	12% 6% 2 5% 4 3 3 3 5% 6% 50%	105035
Transparency	Day	37% 6% 10% 23% 19% 5%	108060
	Night	33% 5% 10% 24% 22% 7%	109530
Seeing	Day	16% 11% 25% 26% 18% 5%	15590
	Night	15% 10% 25% 30% 17% 2	25501

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% 9% 3 6% 3 2 3 2 3 5% 45%	2937
	11th to 20th	Day	11% 10% 3 6% 4 4 3 3 3 4 50%	2940
	21st to end	Day	24% 7% 2 5% 3 3 2 2 3 4 47%	3144
February	1st to 10th	Day	21% 8% 2 6% 4 3 4 3 4 3 43%	1710
	11th to 20th	Day	17% 8% 3 6% 5% 3 4 3 4 4 43%	1765
	21st to end	Day	21% 9% 3 7% 4 4 3 3 4 5% 37%	1650
March	1st to 10th	Day	21% 11% 2 6% 3 4 3 2 3 5% 40%	3436
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 4 6% 45%	3480
	21st to end	Day	16% 8% 3 7% 5% 4 3 3 4 5% 42%	3814
April	1st to 10th	Day	13% 7% 2 6% 4 4 4 4 5% 6% 45%	2257
	11th to 20th	Day	17% 6% 2 6% 4 3 4 2 5% 5% 45%	2254
	21st to end	Day	15% 7% 3 6% 5% 4 5% 4 5% 5% 41%	2280
May	1st to 10th	Day	17% 8% 3 6% 5% 4 5% 3 5% 7% 37%	3783
	11th to 20th	Day	12% 5% 2 6% 5% 5% 5% 3 6% 7% 42%	4082
	21st to end	Day	14% 7% 3 8% 6% 6% 6% 5% 6% 7% 34%	4477
June	1st to 10th	Day	8% 6% 2 6% 5% 5% 6% 5% 7% 9% 41%	2470
	11th to 20th	Day	4 5% 2 5% 6% 6% 5% 6% 7% 10% 43%	2470
	21st to end	Day	4 3 2 5% 6% 6% 6% 4 8% 10% 47%	2470
July	1st to 10th	Day	9% 5% 2 6% 6% 5% 5% 6% 7% 10% 40%	4120
	11th to 20th	Day	6% 4 2 5% 4 5% 5% 4 6% 9% 52%	4120
	21st to end	Day	12% 9% 3 8% 5% 5% 6% 5% 7% 8% 32%	4465
August	1st to 10th	Day	4 3 1 4 4 4 5% 4 6% 8% 58%	4104
	11th to 20th	Day	10% 5% 2 6% 5% 4 5% 5% 7% 10% 40%	3791
	21st to end	Day	6% 3 2 5% 4 5% 6% 5% 6% 8% 50%	4180
September	1st to 10th	Day	12% 6% 3 5% 4 5% 5% 4 5% 7% 46%	2280
	11th to 20th	Day	15% 4 2 6% 4 4 5% 4 6% 6% 44%	2252
	21st to end	Day	11% 4 2 5% 4 4 3 3 4 5% 54%	1995
October	1st to 10th	Day	7% 4 1 5% 3 4 3 3 4 5% 59%	1900
	11th to 20th	Day	14% 5% 1 4 3 2 2 2 4 5% 57%	1900
	21st to end	Day	17% 5% 2 4 4 2 3 3 3 5% 52%	2090
November	1st to 10th	Day	13% 6% 2 4 2 3 3 3 4 6% 55%	1958
	11th to 20th	Day	10% 5% 2 6% 3 3 3 2 5% 7% 55%	1987
	21st to end	Day	16% 8% 3 5% 3 3 3 2 4 4 48%	1725
December	1st to 10th	Day	15% 9% 3 7% 3 3 3 2 4 4 48%	2610
	11th to 20th	Day	14% 10% 4 8% 4 4 3 2 4 4 43%	3031
	21st to end	Day	17% 8% 3 6% 4 4 4 3 4 5% 40%	4488
January	1st to 10th	Night	14% 8% 3 7% 4 3 3 3 4 4 46%	4238
	11th to 20th	Night	15% 7% 2 4 2 2 2 2 3 4 55%	4250
	21st to end	Night	23% 8% 2 4 2 2 2 2 3 4 48%	4546
February	1st to 10th	Night	19% 8% 3 7% 4 3 3 3 5% 5% 41%	2470
	11th to 20th	Night	16% 8% 3 6% 4 3 3 2 4 5% 46%	2301
	21st to end	Night	19% 8% 2 5% 3 3 3 2 5% 5% 46%	1821
March	1st to 10th	Night	20% 8% 3 6% 4 3 3 3 5% 6% 40%	3419
	11th to 20th	Night	16% 7% 2 5% 3 3 3 2 4 5% 51%	3480
	21st to end	Night	11% 7% 3 7% 4 4 4 3 6% 7% 43%	3817
April	1st to 10th	Night	13% 4 2 6% 4 3 3 3 5% 6% 51%	1921
	11th to 20th	Night	12% 5% 2 5% 3 4 3 3 6% 6% 51%	1875
	21st to end	Night	13% 6% 2 5% 3 4 4 3 4 6% 49%	1900
May	1st to 10th	Night	15% 8% 2 5% 4 4 5% 4 5% 8% 39%	3109
	11th to 20th	Night	13% 7% 2 5% 4 5% 4 4 5% 7% 44%	2823
	21st to end	Night	16% 7% 2 6% 5% 4 4 3 5% 8% 41%	3090
June	1st to 10th	Night	6% 4 2 3 3 4 4 4 8% 10% 54%	1710
	11th to 20th	Night	4 4 2 4 3 4 3 3 6% 9% 59%	1710
	21st to end	Night	3 3 1 3 3 3 4 4 6% 8% 61%	1710
July	1st to 10th	Night	7% 4 2 4 4 4 4 4 6% 10% 49%	2850
	11th to 20th	Night	4 3 1 4 2 3 3 4 6% 9% 61%	2850
	21st to end	Night	8% 6% 3 7% 5% 5% 5% 4 7% 8% 42%	3098
August	1st to 10th	Night	3 2 1 3 2 2 3 3 5% 8% 68%	2836
	11th to 20th	Night	5% 3 1 4 3 4 4 4 6% 9% 57%	3037
	21st to end	Night	4 3 1 3 3 4 5% 4 7% 9% 57%	3476
September	1st to 10th	Night	7% 4 2 5% 3 4 4 3 4 7% 57%	1900
	11th to 20th	Night	11% 5% 2 5% 3 3 4 3 5% 7% 52%	1924
	21st to end	Night	9% 4 1 4 2 3 3 3 5% 7% 59%	2166
October	1st to 10th	Night	7% 4 1 4 3 3 3 2 5% 7% 61%	2280
	11th to 20th	Night	11% 4 1 5% 3 2 3 2 4 5% 62%	2280
	21st to end	Night	17% 6% 2 4 3 2 3 2 2 4 56%	2508
November	1st to 10th	Night	12% 5% 2 4 3 2 3 2 5% 6% 56%	2340
	11th to 20th	Night	10% 5% 2 4 4 3 3 3 4 6% 57%	2407
	21st to end	Night	13% 6% 2 4 4 3 3 2 4 6% 52%	2670
December	1st to 10th	Night	14% 7% 2 5% 3 3 2 3 4 5% 52%	4580
	11th to 20th	Night	13% 7% 3 9% 5% 4 3 3 3 4 45%	5153
	21st to end	Night	17% 7% 3 6% 4 4 4 3 4 5% 44%	6490

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	43% 3 6% 24% 20% 4	2938
	11th to 20th	Day	39% 3 10% 21% 22% 4	2940
	21st to end	Day	44% 4 5% 17% 23% 7%	3144
February	1st to 10th	Day	46% 4 9% 21% 16% 5%	1710
	11th to 20th	Day	45% 4 6% 19% 19% 6%	1774
	21st to end	Day	50% 4 7% 14% 16% 9%	1650
March	1st to 10th	Day	47% 6% 7% 13% 18% 10%	3436
	11th to 20th	Day	39% 5% 10% 22% 19% 5%	3480
	21st to end	Day	44% 4 9% 21% 20% 1	3814
April	1st to 10th	Day	38% 6% 10% 20% 21% 5%	2257
	11th to 20th	Day	41% 5% 9% 20% 18% 7%	2254
	21st to end	Day	43% 6% 9% 20% 19% 3	2280
May	1st to 10th	Day	45% 7% 11% 21% 14% 2	3818
	11th to 20th	Day	38% 7% 13% 26% 15% 1	4086
	21st to end	Day	45% 9% 12% 20% 12% 2	4489
June	1st to 10th	Day	36% 9% 13% 24% 16% 2	2470
	11th to 20th	Day	31% 9% 14% 26% 18% 2	2470
	21st to end	Day	29% 8% 13% 27% 20% 4	2470
July	1st to 10th	Day	35% 9% 17% 28% 11% 1	4056
	11th to 20th	Day	26% 7% 10% 33% 21% 3	4051
	21st to end	Day	46% 9% 14% 21% 9%	4325
August	1st to 10th	Day	21% 6% 16% 28% 23% 6%	4090
	11th to 20th	Day	36% 8% 14% 30% 11% 1	3828
	21st to end	Day	28% 7% 13% 30% 18% 3	4179
September	1st to 10th	Day	36% 7% 11% 19% 19% 8%	2280
	11th to 20th	Day	37% 7% 11% 18% 22% 5%	2252
	21st to end	Day	31% 5% 8% 21% 26% 8%	1995
October	1st to 10th	Day	16% 3 5% 13% 37% 25%	3160
	11th to 20th	Day	19% 3 3 19% 37% 19%	3140
	21st to end	Day	30% 4 6% 29% 25% 6%	3428
November	1st to 10th	Day	32% 4 8% 26% 22% 8%	1958
	11th to 20th	Day	29% 4 8% 22% 28% 10%	1987
	21st to end	Day	42% 2 6% 19% 25% 6%	1725
December	1st to 10th	Day	42% 3 6% 26% 19% 4	2610
	11th to 20th	Day	45% 3 5% 21% 21% 4	3028
	21st to end	Day	45% 5% 8% 24% 15% 4	4488
January	1st to 10th	Night	41% 3 7% 20% 26% 3	4238
	11th to 20th	Night	34% 4 10% 21% 25% 5%	4250
	21st to end	Night	42% 3 10% 18% 23% 5%	4546
February	1st to 10th	Night	45% 4 8% 20% 18% 6%	2470
	11th to 20th	Night	42% 3 7% 21% 21% 6%	2302
	21st to end	Night	41% 4 8% 17% 21% 9%	1821
March	1st to 10th	Night	44% 5% 10% 12% 18% 11%	3419
	11th to 20th	Night	37% 5% 8% 26% 18% 6%	3480
	21st to end	Night	39% 5% 9% 24% 21% 2	3817
April	1st to 10th	Night	33% 4 10% 23% 19% 10%	1921
	11th to 20th	Night	33% 5% 9% 23% 21% 9%	1875
	21st to end	Night	36% 4 11% 25% 21% 3	1900
May	1st to 10th	Night	42% 8% 12% 22% 14% 3	3139
	11th to 20th	Night	38% 7% 14% 26% 14% 1	2824
	21st to end	Night	40% 7% 14% 23% 13% 3	3099
June	1st to 10th	Night	23% 8% 16% 31% 20% 2	1710
	11th to 20th	Night	22% 6% 13% 32% 25% 3	1710
	21st to end	Night	20% 7% 13% 30% 24% 7%	1710
July	1st to 10th	Night	29% 7% 19% 28% 16% 1	2805
	11th to 20th	Night	19% 7% 12% 35% 25% 3	2796
	21st to end	Night	37% 9% 14% 25% 14%	2999
August	1st to 10th	Night	15% 5% 16% 33% 26% 6%	2826
	11th to 20th	Night	22% 7% 18% 36% 15% 2	3066
	21st to end	Night	21% 7% 15% 30% 25% 2	3476
September	1st to 10th	Night	27% 7% 11% 25% 22% 9%	1900
	11th to 20th	Night	32% 6% 11% 20% 25% 6%	1924
	21st to end	Night	25% 4 10% 23% 29% 9%	2166
October	1st to 10th	Night	15% 3 7% 15% 29% 31%	3800
	11th to 20th	Night	16% 2 4 16% 38% 24%	3779
	21st to end	Night	27% 3 5% 24% 28% 13%	4120
November	1st to 10th	Night	30% 4 7% 23% 25% 10%	2340
	11th to 20th	Night	29% 3 7% 23% 27% 11%	2407
	21st to end	Night	35% 4 7% 20% 29% 6%	2670
December	1st to 10th	Night	36% 3 7% 31% 18% 4	4580
	11th to 20th	Night	43% 4 5% 20% 20% 7%	5155
	21st to end	Night	42% 5% 9% 24% 16% 3	6490

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	28% 18% 33% 16% 4 1	300
	11th to 20th	Day	24% 24% 36% 14% 2	300
	21st to end	Day	25% 26% 32% 11% 6%	300
February	1st to 10th	Day	30% 17% 34% 13% 5%	270
	11th to 20th	Day	29% 28% 29% 13% 1	270
	21st to end	Day	38% 25% 28% 7% 1	225
March	1st to 10th	Day	26% 20% 34% 14% 5%	270
	11th to 20th	Day	32% 19% 36% 12% 1	270
	21st to end	Day	28% 25% 34% 9% 3	297
April	1st to 10th	Day	22% 19% 36% 15% 7%	437
	11th to 20th	Day	26% 16% 33% 18% 6% 1	452
	21st to end	Day	20% 17% 37% 17% 7% 2	460
May	1st to 10th	Day	20% 16% 32% 24% 8% 1	468
	11th to 20th	Day	15% 9% 31% 27% 15% 2	675
	21st to end	Day	11% 9% 28% 33% 15% 5%	734
June	1st to 10th	Day	9% 5% 22% 31% 26% 6%	680
	11th to 20th	Day	6% 3 20% 39% 26% 5%	680
	21st to end	Day	5% 4 22% 36% 25% 7%	680
July	1st to 10th	Day	6% 3 15% 34% 33% 9%	671
	11th to 20th	Day	5% 2 15% 35% 32% 10%	668
	21st to end	Day	9% 2 13% 34% 31% 12%	739
August	1st to 10th	Day	7% 2 15% 37% 32% 7%	676
	11th to 20th	Day	15% 1 10% 34% 32% 9%	517
	21st to end	Day	9% 2 7% 32% 35% 15%	539
September	1st to 10th	Day	11% 2 13% 29% 35% 9%	490
	11th to 20th	Day	14% 3 13% 27% 33% 10%	462
	21st to end	Day	14% 6% 20% 36% 19% 5%	300
October	1st to 10th	Day	5% 4 28% 39% 20% 4	300
	11th to 20th	Day	15% 12% 33% 25% 12% 2	300
	21st to end	Day	27% 16% 30% 20% 7% 1	330
November	1st to 10th	Day	20% 13% 37% 16% 13% 2	300
	11th to 20th	Day	15% 17% 39% 22% 6% 1	300
	21st to end	Day	27% 18% 27% 19% 9%	300
December	1st to 10th	Day	23% 26% 26% 17% 6% 1	300
	11th to 20th	Day	25% 23% 31% 17% 5%	300
	21st to end	Day	26% 16% 41% 14% 3	330
January	1st to 10th	Night	22% 17% 31% 27% 3	1000
	11th to 20th	Night	22% 18% 34% 23% 3	1000
	21st to end	Night	21% 16% 36% 24% 3	1051
February	1st to 10th	Night	25% 16% 32% 22% 4	950
	11th to 20th	Night	22% 19% 38% 20% 1	826
	21st to end	Night	27% 18% 33% 19% 3	565
March	1st to 10th	Night	21% 14% 31% 29% 5%	570
	11th to 20th	Night	23% 12% 34% 28% 4 1	570
	21st to end	Night	18% 13% 36% 27% 6%	627
April	1st to 10th	Night	17% 15% 35% 27% 6%	570
	11th to 20th	Night	16% 14% 34% 26% 10%	563
	21st to end	Night	15% 11% 37% 27% 9%	570
May	1st to 10th	Night	14% 7% 28% 41% 9% 1	570
	11th to 20th	Night	12% 9% 27% 31% 20% 1	561
	21st to end	Night	11% 5% 25% 33% 22% 5%	617
June	1st to 10th	Night	7% 2 13% 39% 34% 5%	570
	11th to 20th	Night	5% 1 13% 43% 34% 3	570
	21st to end	Night	3 1 14% 41% 36% 5%	570
July	1st to 10th	Night	5% 1 11% 35% 40% 8%	555
	11th to 20th	Night	3 1 11% 34% 42% 8%	552
	21st to end	Night	4 1 10% 36% 40% 10%	624
August	1st to 10th	Night	5% 1 8% 39% 41% 5%	567
	11th to 20th	Night	9% 1 10% 35% 39% 6%	564
	21st to end	Night	7% 1 9% 34% 43% 6%	627
September	1st to 10th	Night	9% 1 11% 31% 44% 4	570
	11th to 20th	Night	14% 1 10% 33% 38% 4	570
	21st to end	Night	11% 3 16% 31% 35% 4	646
October	1st to 10th	Night	8% 3 17% 36% 32% 3	760
	11th to 20th	Night	12% 8% 26% 38% 16% 1	760
	21st to end	Night	20% 10% 25% 29% 14% 2	836
November	1st to 10th	Night	13% 9% 26% 37% 14% 1	780
	11th to 20th	Night	13% 11% 31% 34% 11%	800
	21st to end	Night	16% 17% 28% 27% 11%	870
December	1st to 10th	Night	22% 12% 33% 26% 7%	1000
	11th to 20th	Night	21% 14% 30% 30% 6%	1000
	21st to end	Night	22% 16% 30% 27% 5%	1100

Page generated at 2025-01-19 02:06:44. Version ac07

Copyright © 2025 Attilla Danko.