The Meadow
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Meadow clear sky chart from 2005-11-06 to 2026-08-15.

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% 9% 3 8% 5% 4 4 4 6% 7% 38%	144620
	Night	11% 9% 4 9% 5% 5% 4 4 5% 7% 37%	137647
Transparency	Day	45% 3 12% 27% 12% 1	148172
	Night	47% 3 12% 24% 13% 1	142174
Seeing	Day	17% 11% 30% 26% 13% 3	18518
	Night	16% 10% 31% 32% 10% 1	28316

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	9% 13% 5% 20% 9% 5% 5% 3 4 6% 21%	4691
	11th to 20th	Day	4 13% 7% 15% 8% 5% 7% 7% 8% 5% 20%	4710
	21st to end	Day	5% 12% 6% 11% 5% 5% 7% 5% 5% 7% 33%	5752
February	1st to 10th	Day	8% 12% 5% 11% 7% 6% 6% 5% 5% 7% 29%	1890
	11th to 20th	Day	8% 11% 5% 11% 5% 6% 4 4 5% 6% 35%	1844
	21st to end	Day	11% 12% 4 9% 6% 5% 4 4 5% 7% 33%	1657
March	1st to 10th	Day	12% 9% 3 5% 4 3 3 3 5% 7% 46%	4851
	11th to 20th	Day	10% 9% 3 7% 4 4 4 3 5% 9% 40%	5090
	21st to end	Day	22% 11% 3 10% 5% 4 5% 3 5% 6% 26%	5717
April	1st to 10th	Day	17% 11% 4 8% 4 4 4 3 6% 6% 33%	2520
	11th to 20th	Day	19% 12% 4 8% 5% 4 4 3 5% 5% 31%	2494
	21st to end	Day	19% 12% 3 7% 4 5% 5% 4 6% 6% 29%	2690
May	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 5% 7% 49%	8050
	11th to 20th	Day	14% 8% 2 6% 4 3 4 3 5% 6% 45%	8222
	21st to end	Day	15% 8% 3 7% 5% 4 5% 3 6% 7% 38%	9047
June	1st to 10th	Day	12% 5% 2 5% 4 5% 4 4 6% 8% 45%	2940
	11th to 20th	Day	14% 7% 3 7% 5% 5% 4 5% 6% 9% 36%	2940
	21st to end	Day	11% 5% 2 7% 5% 6% 5% 4 7% 9% 38%	2940
July	1st to 10th	Day	10% 6% 3 6% 4 4 5% 4 8% 10% 39%	8280
	11th to 20th	Day	7% 3 2 4 3 3 3 3 5% 9% 58%	8280
	21st to end	Day	8% 5% 2 6% 5% 4 5% 4 7% 9% 46%	8990
August	1st to 10th	Day	12% 6% 3 5% 4 4 5% 4 7% 8% 42%	4376
	11th to 20th	Day	13% 6% 2 6% 4 4 5% 4 7% 8% 43%	4224
	21st to end	Day	9% 5% 3 7% 4 5% 4 3 6% 8% 45%	4412
September	1st to 10th	Day	12% 6% 2 5% 4 4 4 3 6% 8% 47%	2400
	11th to 20th	Day	13% 6% 2 5% 5% 4 4 4 6% 8% 44%	2400
	21st to end	Day	14% 7% 2 6% 4 3 3 3 6% 7% 44%	2092
October	1st to 10th	Day	14% 6% 2 6% 4 3 4 3 6% 7% 45%	2000
	11th to 20th	Day	15% 11% 3 7% 4 4 5% 3 5% 7% 38%	2000
	21st to end	Day	16% 14% 4 7% 3 3 4 3 4 6% 36%	2140
November	1st to 10th	Day	12% 10% 5% 9% 5% 4 4 3 5% 6% 35%	1773
	11th to 20th	Day	11% 15% 7% 10% 6% 4 4 4 5% 5% 29%	1680
	21st to end	Day	13% 13% 4 10% 5% 3 4 3 5% 7% 33%	1680
December	1st to 10th	Day	7% 11% 5% 13% 13% 7% 5% 4 6% 6% 23%	2690
	11th to 20th	Day	11% 14% 6% 12% 8% 5% 4 4 5% 5% 27%	3088
	21st to end	Day	17% 20% 8% 20% 6% 4 3 3 3 4 13%	4070
January	1st to 10th	Night	8% 13% 5% 15% 8% 6% 4 3 5% 6% 27%	8232
	11th to 20th	Night	5% 12% 5% 14% 8% 7% 8% 8% 7% 5% 19%	8280
	21st to end	Night	6% 13% 6% 10% 6% 4 6% 4 6% 7% 33%	8446
February	1st to 10th	Night	6% 12% 5% 11% 7% 7% 4 4 5% 7% 32%	2730
	11th to 20th	Night	6% 10% 4 9% 6% 6% 5% 4 5% 7% 38%	2663
	21st to end	Night	11% 10% 4 9% 6% 5% 5% 4 4 6% 36%	2147
March	1st to 10th	Night	10% 7% 3 6% 5% 4 4 3 5% 7% 46%	5267
	11th to 20th	Night	9% 7% 3 8% 5% 5% 5% 4 6% 9% 39%	5090
	21st to end	Night	23% 12% 4 10% 4 3 3 3 4 6% 28%	5453
April	1st to 10th	Night	16% 12% 2 7% 4 3 4 3 5% 7% 35%	2100
	11th to 20th	Night	20% 10% 4 7% 4 4 3 3 5% 5% 35%	2075
	21st to end	Night	18% 9% 3 7% 4 4 5% 2 5% 6% 37%	1927
May	1st to 10th	Night	10% 7% 3 6% 4 4 4 3 5% 7% 48%	4832
	11th to 20th	Night	15% 6% 2 5% 3 4 3 3 5% 6% 48%	4670
	21st to end	Night	14% 9% 3 8% 5% 5% 4 3 5% 7% 38%	5139
June	1st to 10th	Night	12% 5% 2 5% 4 4 5% 3 7% 7% 45%	1680
	11th to 20th	Night	10% 5% 3 8% 4 5% 3 4 6% 7% 45%	1680
	21st to end	Night	7% 5% 2 5% 4 4 5% 4 7% 8% 49%	1680
July	1st to 10th	Night	9% 5% 2 6% 4 4 5% 5% 6% 10% 45%	4708
	11th to 20th	Night	5% 3 1 4 3 3 4 4 6% 10% 57%	4707
	21st to end	Night	7% 5% 2 6% 4 4 4 4 6% 8% 51%	5117
August	1st to 10th	Night	11% 7% 3 7% 5% 4 4 3 5% 7% 46%	3000
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 5% 8% 49%	2924
	21st to end	Night	9% 6% 3 7% 4 4 4 4 5% 7% 48%	3487
September	1st to 10th	Night	10% 5% 2 5% 3 4 4 3 4 8% 53%	2000
	11th to 20th	Night	10% 5% 3 5% 3 3 4 3 5% 8% 52%	2000
	21st to end	Night	13% 5% 2 4 3 3 4 3 4 7% 51%	2284
October	1st to 10th	Night	13% 6% 2 6% 4 3 4 3 4 6% 51%	2400
	11th to 20th	Night	15% 10% 3 6% 4 3 4 3 4 7% 42%	2400
	21st to end	Night	16% 12% 4 7% 3 4 3 3 4 6% 37%	2699
November	1st to 10th	Night	12% 10% 3 7% 5% 4 3 3 5% 6% 41%	2741
	11th to 20th	Night	12% 12% 5% 11% 5% 5% 4 4 5% 5% 33%	2940
	21st to end	Night	14% 11% 4 10% 5% 4 4 3 4 6% 35%	2940
December	1st to 10th	Night	7% 8% 5% 15% 8% 8% 5% 3 5% 7% 29%	4720
	11th to 20th	Night	10% 15% 6% 16% 7% 5% 5% 4 4 5% 23%	5339
	21st to end	Night	20% 16% 7% 17% 6% 4 4 3 3 4 16%	7150

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	67% 2 9% 15% 6%	4692
	11th to 20th	Day	62% 2 6% 17% 11%	4710
	21st to end	Day	52% 3 13% 23% 10%	5752
February	1st to 10th	Day	54% 4 14% 18% 9% 1	1890
	11th to 20th	Day	49% 5% 11% 27% 8% 1	1853
	21st to end	Day	50% 5% 13% 21% 11% 1	1657
March	1st to 10th	Day	38% 2 17% 27% 13% 3	4851
	11th to 20th	Day	43% 2 14% 29% 10% 1	5090
	21st to end	Day	60% 2 10% 18% 9% 1	5719
April	1st to 10th	Day	51% 4 10% 21% 12% 1	2520
	11th to 20th	Day	55% 4 9% 19% 11% 2	2494
	21st to end	Day	54% 5% 11% 21% 9%	2690
May	1st to 10th	Day	36% 3 9% 31% 20% 2	8090
	11th to 20th	Day	41% 3 8% 27% 18% 4	8226
	21st to end	Day	47% 2 8% 30% 11% 2	9061
June	1st to 10th	Day	36% 5% 14% 30% 13% 1	2940
	11th to 20th	Day	44% 5% 14% 24% 13% 1	2940
	21st to end	Day	42% 5% 14% 26% 10% 2	2940
July	1st to 10th	Day	40% 2 17% 32% 7%	8211
	11th to 20th	Day	25% 2 13% 41% 18% 1	8205
	21st to end	Day	36% 3 12% 32% 17% 1	8794
August	1st to 10th	Day	39% 4 12% 29% 14% 1	4361
	11th to 20th	Day	39% 4 13% 34% 10%	4263
	21st to end	Day	38% 3 15% 30% 13% 1	4411
September	1st to 10th	Day	36% 5% 13% 33% 14%	2400
	11th to 20th	Day	38% 4 17% 32% 9%	2400
	21st to end	Day	39% 4 11% 34% 12%	2092
October	1st to 10th	Day	30% 2 8% 37% 23%	3260
	11th to 20th	Day	41% 2 11% 26% 19% 2	3240
	21st to end	Day	45% 2 14% 29% 9%	3442
November	1st to 10th	Day	49% 4 13% 19% 13% 2	1773
	11th to 20th	Day	56% 4 12% 18% 9% 1	1680
	21st to end	Day	51% 4 17% 20% 7% 1	1680
December	1st to 10th	Day	62% 3 15% 14% 5%	2690
	11th to 20th	Day	60% 2 12% 19% 7%	3085
	21st to end	Day	78% 2 7% 9% 4	4070
January	1st to 10th	Night	60% 2 14% 17% 8%	8233
	11th to 20th	Night	64% 3 8% 14% 11%	8280
	21st to end	Night	52% 2 10% 24% 12%	8446
February	1st to 10th	Night	53% 3 11% 22% 10% 1	2730
	11th to 20th	Night	44% 4 14% 27% 9% 1	2664
	21st to end	Night	48% 4 12% 23% 12% 1	2147
March	1st to 10th	Night	39% 3 13% 24% 17% 4	5267
	11th to 20th	Night	42% 3 14% 25% 15% 1	5090
	21st to end	Night	60% 2 9% 17% 11%	5453
April	1st to 10th	Night	49% 4 8% 22% 16% 1	2100
	11th to 20th	Night	51% 3 9% 20% 14% 2	2075
	21st to end	Night	48% 3 9% 23% 15% 2	1927
May	1st to 10th	Night	37% 2 8% 31% 20% 1	4857
	11th to 20th	Night	38% 2 9% 23% 22% 5%	4671
	21st to end	Night	48% 2 9% 27% 12% 2	5149
June	1st to 10th	Night	35% 4 12% 29% 17% 2	1680
	11th to 20th	Night	38% 5% 13% 23% 18% 3	1680
	21st to end	Night	32% 5% 16% 31% 14% 3	1680
July	1st to 10th	Night	36% 3 20% 30% 11% 1	4670
	11th to 20th	Night	23% 2 13% 39% 21% 1	4662
	21st to end	Night	33% 2 14% 32% 18% 2	5002
August	1st to 10th	Night	39% 3 11% 28% 14% 3	2991
	11th to 20th	Night	36% 3 13% 32% 13% 1	2951
	21st to end	Night	38% 3 16% 29% 12% 2	3487
September	1st to 10th	Night	31% 5% 12% 36% 15% 1	2000
	11th to 20th	Night	32% 4 17% 32% 15%	2000
	21st to end	Night	33% 4 13% 33% 15% 1	2284
October	1st to 10th	Night	26% 2 6% 36% 26% 4	3920
	11th to 20th	Night	36% 2 11% 26% 23% 2	3899
	21st to end	Night	47% 2 10% 27% 13%	4347
November	1st to 10th	Night	44% 3 12% 25% 14% 1	2741
	11th to 20th	Night	53% 4 12% 19% 11% 1	2940
	21st to end	Night	51% 3 15% 23% 7% 1	2940
December	1st to 10th	Night	56% 4 17% 19% 4	4720
	11th to 20th	Night	65% 3 10% 16% 6% 1	5341
	21st to end	Night	73% 2 8% 12% 5%	7150

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	14% 15% 33% 27% 10% 2	330
	11th to 20th	Day	15% 15% 41% 23% 4 1	330
	21st to end	Day	13% 13% 39% 24% 10% 1	363
February	1st to 10th	Day	15% 15% 47% 15% 6% 1	330
	11th to 20th	Day	13% 19% 42% 20% 5% 1	330
	21st to end	Day	16% 18% 38% 26% 2	273
March	1st to 10th	Day	17% 14% 46% 17% 6% 1	330
	11th to 20th	Day	20% 15% 38% 20% 6% 2	330
	21st to end	Day	25% 16% 30% 20% 7% 3	420
April	1st to 10th	Day	24% 18% 31% 21% 6%	540
	11th to 20th	Day	27% 17% 24% 23% 7% 1	532
	21st to end	Day	26% 12% 30% 21% 9% 1	710
May	1st to 10th	Day	18% 13% 31% 25% 11% 2	753
	11th to 20th	Day	20% 13% 27% 25% 13% 3	775
	21st to end	Day	19% 8% 29% 25% 15% 3	844
June	1st to 10th	Day	12% 9% 25% 34% 17% 3	780
	11th to 20th	Day	17% 9% 33% 28% 11% 2	780
	21st to end	Day	13% 8% 29% 29% 15% 5%	780
July	1st to 10th	Day	9% 4 20% 32% 25% 11%	771
	11th to 20th	Day	8% 6% 26% 31% 21% 8%	768
	21st to end	Day	7% 4 25% 37% 19% 7%	849
August	1st to 10th	Day	12% 5% 21% 33% 22% 6%	776
	11th to 20th	Day	15% 5% 21% 31% 24% 5%	736
	21st to end	Day	11% 4 24% 34% 22% 5%	644
September	1st to 10th	Day	14% 8% 26% 30% 15% 6%	530
	11th to 20th	Day	15% 4 27% 31% 21% 2	530
	21st to end	Day	18% 13% 24% 24% 16% 4	348
October	1st to 10th	Day	15% 14% 28% 27% 14% 2	330
	11th to 20th	Day	23% 16% 35% 19% 6%	330
	21st to end	Day	26% 14% 35% 17% 6% 2	363
November	1st to 10th	Day	19% 14% 36% 19% 10% 1	330
	11th to 20th	Day	18% 18% 41% 19% 4	330
	21st to end	Day	24% 15% 36% 21% 4	330
December	1st to 10th	Day	17% 9% 42% 23% 7% 1	330
	11th to 20th	Day	20% 18% 37% 19% 6%	330
	21st to end	Day	25% 16% 38% 17% 3 1	363
January	1st to 10th	Night	12% 13% 35% 30% 8% 1	1050
	11th to 20th	Night	17% 12% 35% 29% 6% 1	1050
	21st to end	Night	17% 12% 35% 28% 7% 1	1155
February	1st to 10th	Night	12% 14% 40% 26% 7% 1	1050
	11th to 20th	Night	12% 13% 41% 26% 7%	1029
	21st to end	Night	17% 13% 35% 28% 7%	763
March	1st to 10th	Night	16% 12% 37% 26% 8% 1	744
	11th to 20th	Night	18% 13% 36% 27% 6% 1	630
	21st to end	Night	22% 10% 32% 26% 8% 2	693
April	1st to 10th	Night	22% 14% 35% 24% 6%	630
	11th to 20th	Night	25% 11% 30% 27% 7%	623
	21st to end	Night	21% 10% 32% 27% 9% 1	630
May	1st to 10th	Night	20% 10% 31% 33% 6% 1	630
	11th to 20th	Night	19% 9% 29% 32% 10% 1	621
	21st to end	Night	14% 9% 26% 37% 14%	683
June	1st to 10th	Night	14% 4 28% 40% 13% 1	630
	11th to 20th	Night	13% 5% 34% 39% 9%	630
	21st to end	Night	10% 4 24% 45% 16% 1	630
July	1st to 10th	Night	7% 1 19% 43% 27% 2	615
	11th to 20th	Night	6% 3 22% 46% 21% 2	612
	21st to end	Night	6% 2 21% 47% 22% 2	690
August	1st to 10th	Night	7% 5% 14% 50% 23% 1	627
	11th to 20th	Night	14% 2 17% 38% 26% 3	606
	21st to end	Night	9% 3 23% 38% 24% 2	660
September	1st to 10th	Night	11% 5% 23% 41% 16% 4	600
	11th to 20th	Night	11% 6% 26% 37% 17% 3	600
	21st to end	Night	15% 9% 27% 31% 16% 1	705
October	1st to 10th	Night	16% 8% 30% 32% 13% 2	800
	11th to 20th	Night	19% 11% 34% 29% 7% 1	800
	21st to end	Night	23% 12% 27% 31% 7%	880
November	1st to 10th	Night	19% 9% 35% 29% 8% 1	895
	11th to 20th	Night	18% 13% 35% 27% 7% 1	1050
	21st to end	Night	19% 14% 34% 26% 6%	1050
December	1st to 10th	Night	16% 9% 38% 29% 7% 1	1050
	11th to 20th	Night	19% 12% 39% 25% 6% 1	1050
	21st to end	Night	24% 10% 35% 25% 5%	1155

Page generated at 2026-08-12 02:37:17. Version ac07

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