Churchill Chimes Equestrian Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Churchill Chimes Equestrian Center clear sky chart from 2005-11-06 to 2024-01-15.

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	15% 9% 4 7% 6% 4 5% 5% 6% 7% 32%	74680
	Night	15% 10% 4 7% 6% 3 5% 5% 5% 7% 33%	75089
Transparency	Day	48% 9% 13% 19% 10% 1	74393
	Night	48% 9% 13% 19% 10% 1	74910
Seeing	Day	20% 16% 31% 21% 9% 3	13302
	Night	20% 14% 32% 24% 9% 1	22803

By Month

Percentage Cloud Cover NE (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	15% 14% 6% 8% 8% 5% 6% 4 5% 6% 23%	1517
	11th to 20th	Day	16% 17% 6% 9% 8% 4 6% 5% 5% 5% 19%	1580
	21st to end	Day	13% 13% 6% 13% 8% 4 6% 5% 5% 6% 20%	1782
February	1st to 10th	Day	15% 17% 5% 10% 8% 5% 6% 5% 5% 5% 18%	1620
	11th to 20th	Day	13% 13% 8% 10% 7% 3 5% 4 4 6% 25%	1573
	21st to end	Day	18% 15% 6% 9% 7% 4 4 4 4 5% 26%	1375
March	1st to 10th	Day	14% 11% 5% 9% 8% 4 5% 4 6% 5% 29%	1977
	11th to 20th	Day	13% 13% 5% 7% 6% 4 6% 4 5% 5% 32%	1980
	21st to end	Day	19% 10% 3 7% 6% 3 5% 4 4 5% 34%	2178
April	1st to 10th	Day	19% 12% 4 7% 6% 3 5% 5% 5% 7% 27%	2137
	11th to 20th	Day	19% 10% 3 6% 5% 2 4 5% 5% 6% 35%	2190
	21st to end	Day	21% 8% 4 6% 5% 3 5% 4 5% 6% 33%	2340
May	1st to 10th	Day	17% 8% 4 7% 6% 3 5% 4 5% 7% 33%	2348
	11th to 20th	Day	14% 8% 3 6% 5% 3 4 5% 6% 7% 39%	2478
	21st to end	Day	12% 5% 3 6% 6% 4 5% 5% 6% 7% 42%	2725
June	1st to 10th	Day	15% 6% 4 6% 6% 3 5% 5% 7% 8% 36%	2520
	11th to 20th	Day	13% 6% 3 5% 5% 3 6% 5% 6% 9% 39%	2520
	21st to end	Day	15% 5% 2 6% 6% 4 6% 6% 6% 9% 37%	2520
July	1st to 10th	Day	9% 5% 2 4 5% 3 5% 5% 6% 9% 46%	2520
	11th to 20th	Day	11% 5% 3 6% 6% 3 6% 6% 8% 10% 36%	2520
	21st to end	Day	9% 5% 3 7% 7% 5% 6% 8% 7% 10% 34%	2605
August	1st to 10th	Day	10% 5% 2 6% 6% 4 6% 6% 8% 10% 37%	2327
	11th to 20th	Day	8% 7% 3 6% 6% 4 6% 7% 7% 9% 38%	2303
	21st to end	Day	12% 6% 3 5% 5% 4 5% 6% 6% 8% 39%	2471
September	1st to 10th	Day	13% 6% 2 6% 6% 2 4 5% 7% 8% 40%	2160
	11th to 20th	Day	12% 5% 3 5% 6% 3 4 6% 6% 8% 43%	2073
	21st to end	Day	14% 7% 3 6% 6% 3 6% 5% 5% 8% 38%	1931
October	1st to 10th	Day	19% 9% 3 6% 6% 4 4 5% 4 7% 33%	1800
	11th to 20th	Day	21% 9% 3 8% 7% 3 6% 5% 5% 6% 28%	1800
	21st to end	Day	24% 13% 4 8% 5% 4 5% 5% 4 6% 22%	1980
November	1st to 10th	Day	15% 10% 4 8% 7% 4 5% 5% 5% 8% 31%	1592
	11th to 20th	Day	16% 11% 4 9% 7% 4 6% 6% 6% 6% 23%	1520
	21st to end	Day	19% 13% 5% 9% 8% 3 6% 5% 4 7% 21%	1520
December	1st to 10th	Day	17% 15% 5% 12% 9% 5% 7% 5% 6% 6% 14%	1520
	11th to 20th	Day	17% 14% 4 8% 7% 3 5% 6% 5% 8% 23%	1906
	21st to end	Day	26% 17% 6% 12% 8% 4 5% 4 4 4 12%	2772
January	1st to 10th	Night	17% 14% 6% 9% 7% 4 6% 4 5% 6% 23%	2649
	11th to 20th	Night	18% 15% 6% 10% 9% 4 5% 5% 5% 6% 17%	2468
	21st to end	Night	13% 11% 7% 8% 7% 4 6% 5% 5% 7% 26%	2574
February	1st to 10th	Night	14% 15% 6% 10% 7% 4 6% 6% 5% 5% 21%	2340
	11th to 20th	Night	15% 12% 6% 9% 6% 3 5% 5% 5% 7% 26%	2273
	21st to end	Night	14% 12% 4 9% 7% 4 5% 5% 6% 6% 28%	1880
March	1st to 10th	Night	13% 9% 4 8% 7% 4 6% 4 5% 5% 35%	1970
	11th to 20th	Night	15% 11% 5% 7% 7% 3 5% 5% 4 5% 34%	1979
	21st to end	Night	15% 8% 3 6% 6% 3 5% 5% 5% 6% 37%	2178
April	1st to 10th	Night	19% 10% 4 5% 6% 4 5% 5% 5% 6% 32%	1822
	11th to 20th	Night	16% 7% 3 6% 6% 3 5% 4 5% 5% 38%	1733
	21st to end	Night	16% 7% 4 7% 6% 4 4 5% 5% 8% 34%	1620
May	1st to 10th	Night	17% 7% 2 5% 5% 3 5% 6% 5% 8% 38%	1610
	11th to 20th	Night	13% 5% 2 5% 5% 4 4 4 6% 7% 45%	1415
	21st to end	Night	10% 4 1 4 5% 2 5% 5% 5% 8% 51%	1550
June	1st to 10th	Night	12% 4 3 6% 6% 3 5% 5% 5% 9% 41%	1440
	11th to 20th	Night	9% 6% 2 5% 6% 4 5% 5% 6% 9% 43%	1440
	21st to end	Night	13% 5% 2 6% 5% 2 5% 5% 6% 8% 43%	1440
July	1st to 10th	Night	6% 4 2 3 5% 3 4 5% 5% 8% 54%	1440
	11th to 20th	Night	9% 5% 2 4 5% 2 4 5% 7% 9% 48%	1440
	21st to end	Night	8% 4 2 3 5% 3 5% 5% 7% 9% 49%	1709
August	1st to 10th	Night	7% 5% 2 5% 6% 3 4 5% 6% 8% 49%	1611
	11th to 20th	Night	7% 5% 2 4 5% 3 5% 5% 5% 10% 51%	1598
	21st to end	Night	9% 5% 3 6% 5% 3 4 5% 6% 6% 48%	1867
September	1st to 10th	Night	10% 5% 2 5% 5% 4 6% 6% 6% 7% 46%	1800
	11th to 20th	Night	11% 4 2 4 4 3 3 4 5% 7% 53%	1884
	21st to end	Night	16% 6% 2 6% 5% 3 3 4 5% 7% 43%	2027
October	1st to 10th	Night	15% 7% 3 7% 6% 4 5% 5% 6% 6% 37%	2160
	11th to 20th	Night	19% 9% 3 7% 6% 3 5% 5% 5% 6% 32%	2160
	21st to end	Night	21% 10% 4 6% 7% 4 5% 5% 5% 6% 27%	2376
November	1st to 10th	Night	18% 8% 2 7% 5% 3 4 4 6% 7% 35%	2484
	11th to 20th	Night	16% 10% 4 8% 7% 4 5% 5% 6% 7% 27%	2660
	21st to end	Night	19% 12% 3 7% 6% 4 7% 6% 6% 7% 23%	2660
December	1st to 10th	Night	18% 14% 5% 9% 8% 4 6% 5% 5% 7% 19%	2660
	11th to 20th	Night	15% 17% 5% 10% 7% 4 6% 5% 6% 5% 20%	3288
	21st to end	Night	27% 15% 4 10% 6% 4 6% 4 4 5% 13%	4884

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	58% 11% 13% 12% 6%	1518
	11th to 20th	Day	65% 9% 10% 10% 5%	1580
	21st to end	Day	62% 8% 12% 11% 7% 1	1782
February	1st to 10th	Day	65% 8% 10% 14% 3 1	1620
	11th to 20th	Day	58% 7% 11% 15% 7% 1	1582
	21st to end	Day	60% 6% 12% 15% 6% 1	1375
March	1st to 10th	Day	52% 8% 14% 16% 9% 1	1980
	11th to 20th	Day	52% 7% 11% 17% 12% 2	1980
	21st to end	Day	51% 7% 10% 16% 14% 2	2178
April	1st to 10th	Day	54% 6% 12% 16% 9% 1	2137
	11th to 20th	Day	47% 7% 11% 21% 13% 1	2190
	21st to end	Day	50% 8% 11% 17% 11% 3	2340
May	1st to 10th	Day	48% 7% 10% 19% 13% 2	2348
	11th to 20th	Day	42% 8% 12% 24% 14% 1	2482
	21st to end	Day	38% 9% 15% 23% 12% 2	2725
June	1st to 10th	Day	42% 10% 13% 19% 14% 1	2520
	11th to 20th	Day	39% 9% 13% 23% 15% 1	2520
	21st to end	Day	40% 9% 15% 22% 13% 1	2520
July	1st to 10th	Day	33% 9% 14% 24% 18% 2	2450
	11th to 20th	Day	36% 10% 17% 26% 10% 1	2445
	21st to end	Day	39% 12% 16% 20% 12% 1	2459
August	1st to 10th	Day	37% 11% 17% 23% 12% 1	2314
	11th to 20th	Day	38% 11% 16% 24% 11%	2303
	21st to end	Day	39% 8% 16% 25% 11% 1	2471
September	1st to 10th	Day	38% 10% 15% 25% 10% 1	2160
	11th to 20th	Day	35% 9% 16% 26% 14%	2073
	21st to end	Day	43% 8% 15% 25% 8%	1931
October	1st to 10th	Day	49% 7% 14% 18% 11% 1	1800
	11th to 20th	Day	54% 8% 14% 17% 6% 1	1800
	21st to end	Day	60% 9% 12% 14% 5% 1	1980
November	1st to 10th	Day	48% 9% 15% 18% 8% 1	1592
	11th to 20th	Day	54% 12% 14% 12% 7% 1	1520
	21st to end	Day	59% 10% 14% 14% 3	1520
December	1st to 10th	Day	65% 11% 13% 9% 3	1520
	11th to 20th	Day	57% 12% 15% 11% 5%	1906
	21st to end	Day	73% 10% 8% 8% 2	2772
January	1st to 10th	Night	59% 9% 11% 15% 6%	2649
	11th to 20th	Night	65% 10% 11% 9% 4 1	2468
	21st to end	Night	55% 9% 13% 15% 7% 1	2574
February	1st to 10th	Night	60% 9% 10% 16% 4 1	2340
	11th to 20th	Night	57% 8% 11% 16% 7% 1	2275
	21st to end	Night	54% 7% 14% 17% 7%	1880
March	1st to 10th	Night	48% 7% 15% 19% 9% 2	1980
	11th to 20th	Night	51% 7% 10% 20% 11% 2	1980
	21st to end	Night	46% 6% 10% 21% 15% 2	2178
April	1st to 10th	Night	50% 7% 11% 18% 13% 1	1822
	11th to 20th	Night	46% 7% 9% 20% 16% 2	1733
	21st to end	Night	46% 9% 12% 18% 14% 2	1620
May	1st to 10th	Night	43% 8% 10% 21% 16% 3	1610
	11th to 20th	Night	37% 7% 11% 24% 17% 4	1416
	21st to end	Night	30% 8% 16% 24% 18% 4	1551
June	1st to 10th	Night	38% 8% 12% 24% 16% 2	1440
	11th to 20th	Night	36% 7% 13% 21% 21% 2	1440
	21st to end	Night	37% 8% 14% 23% 17% 1	1440
July	1st to 10th	Night	25% 8% 14% 27% 23% 3	1400
	11th to 20th	Night	30% 8% 14% 30% 17% 2	1392
	21st to end	Night	29% 9% 15% 29% 15% 2	1614
August	1st to 10th	Night	32% 7% 19% 28% 14% 1	1600
	11th to 20th	Night	28% 7% 17% 31% 14% 1	1598
	21st to end	Night	33% 9% 13% 28% 15% 1	1867
September	1st to 10th	Night	34% 9% 17% 25% 14% 1	1800
	11th to 20th	Night	30% 7% 13% 33% 17% 1	1884
	21st to end	Night	39% 9% 13% 27% 11%	2027
October	1st to 10th	Night	44% 9% 12% 19% 15% 1	2160
	11th to 20th	Night	49% 10% 14% 20% 7%	2160
	21st to end	Night	54% 9% 13% 15% 10%	2376
November	1st to 10th	Night	45% 7% 14% 21% 11% 1	2484
	11th to 20th	Night	52% 10% 14% 15% 9% 1	2660
	21st to end	Night	54% 12% 18% 12% 3	2660
December	1st to 10th	Night	62% 10% 14% 11% 3	2660
	11th to 20th	Night	61% 10% 13% 13% 4	3288
	21st to end	Night	70% 10% 11% 7% 2	4884

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	23% 24% 29% 18% 6%	180
	11th to 20th	Day	25% 31% 26% 15% 3 1	216
	21st to end	Day	22% 27% 35% 14% 2	264
February	1st to 10th	Day	29% 28% 31% 11% 2	240
	11th to 20th	Day	23% 28% 40% 7% 1	240
	21st to end	Day	37% 21% 34% 8%	224
March	1st to 10th	Day	24% 22% 36% 15% 3	420
	11th to 20th	Day	23% 22% 34% 17% 3 1	420
	21st to end	Day	31% 19% 30% 15% 4 1	462
April	1st to 10th	Day	26% 20% 34% 13% 6%	420
	11th to 20th	Day	28% 20% 25% 17% 7% 3	412
	21st to end	Day	26% 16% 36% 14% 7% 1	420
May	1st to 10th	Day	23% 14% 31% 20% 8% 4	423
	11th to 20th	Day	18% 16% 30% 24% 7% 4	447
	21st to end	Day	15% 12% 29% 27% 13% 4	485
June	1st to 10th	Day	16% 14% 32% 28% 9% 1	450
	11th to 20th	Day	15% 15% 28% 27% 13% 2	450
	21st to end	Day	19% 8% 33% 27% 11% 2	450
July	1st to 10th	Day	9% 8% 26% 34% 18% 4	445
	11th to 20th	Day	14% 7% 27% 31% 15% 7%	444
	21st to end	Day	8% 8% 35% 33% 11% 6%	488
August	1st to 10th	Day	11% 8% 26% 32% 15% 8%	446
	11th to 20th	Day	13% 8% 23% 28% 22% 7%	439
	21st to end	Day	13% 10% 29% 25% 16% 7%	495
September	1st to 10th	Day	12% 10% 28% 28% 15% 8%	450
	11th to 20th	Day	10% 8% 28% 24% 18% 11%	450
	21st to end	Day	15% 12% 29% 26% 12% 6%	450
October	1st to 10th	Day	22% 13% 28% 17% 17% 3	450
	11th to 20th	Day	22% 22% 32% 17% 6% 1	450
	21st to end	Day	29% 21% 28% 17% 5%	495
November	1st to 10th	Day	24% 23% 31% 16% 7% 1	259
	11th to 20th	Day	23% 26% 32% 15% 4 1	180
	21st to end	Day	24% 26% 39% 10% 2	180
December	1st to 10th	Day	24% 22% 36% 13% 4 1	180
	11th to 20th	Day	31% 21% 33% 12% 3 1	180
	21st to end	Day	30% 22% 36% 12% 1	198
January	1st to 10th	Night	23% 23% 36% 13% 5%	760
	11th to 20th	Night	28% 17% 32% 18% 4 1	737
	21st to end	Night	19% 16% 37% 22% 6%	792
February	1st to 10th	Night	22% 21% 39% 16% 2	720
	11th to 20th	Night	23% 19% 37% 18% 3	703
	21st to end	Night	23% 20% 38% 15% 4	592
March	1st to 10th	Night	20% 20% 37% 19% 3	720
	11th to 20th	Night	22% 19% 36% 18% 4 1	720
	21st to end	Night	20% 15% 33% 25% 6% 1	792
April	1st to 10th	Night	25% 17% 34% 22% 3	720
	11th to 20th	Night	18% 18% 35% 20% 8% 1	669
	21st to end	Night	20% 14% 34% 24% 9%	540
May	1st to 10th	Night	20% 9% 28% 30% 11% 2	530
	11th to 20th	Night	18% 8% 32% 29% 13% 1	354
	21st to end	Night	11% 8% 28% 35% 17% 1	389
June	1st to 10th	Night	13% 8% 31% 36% 12%	360
	11th to 20th	Night	12% 8% 30% 36% 14% 1	360
	21st to end	Night	14% 6% 30% 37% 13% 1	360
July	1st to 10th	Night	7% 6% 27% 39% 20% 1	350
	11th to 20th	Night	12% 3 29% 34% 20% 1	348
	21st to end	Night	10% 3 26% 41% 18% 2	529
August	1st to 10th	Night	10% 4 21% 36% 27% 2	537
	11th to 20th	Night	7% 4 19% 43% 24% 3	534
	21st to end	Night	12% 5% 28% 34% 19% 3	679
September	1st to 10th	Night	12% 8% 25% 34% 18% 4	720
	11th to 20th	Night	13% 8% 24% 30% 21% 5%	720
	21st to end	Night	17% 9% 23% 31% 16% 4	720
October	1st to 10th	Night	19% 8% 30% 26% 15% 2	720
	11th to 20th	Night	23% 16% 32% 21% 7% 1	720
	21st to end	Night	28% 15% 31% 22% 3 1	792
November	1st to 10th	Night	24% 13% 32% 23% 8% 1	740
	11th to 20th	Night	22% 19% 32% 19% 6% 1	760
	21st to end	Night	25% 18% 30% 21% 5%	760
December	1st to 10th	Night	28% 18% 35% 16% 3	760
	11th to 20th	Night	21% 20% 37% 18% 3 1	760
	21st to end	Night	30% 17% 36% 15% 2	836

Page generated at 2024-01-11 22:33:45. Version ac07

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