Saint-Thomas-de-Caxton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Thomas-de-Caxton clear sky chart from 2005-11-06 to 2026-07-16.

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	18% 9% 3 8% 5% 4 4 4 5% 6% 32%	138233
	Night	18% 11% 4 9% 5% 4 4 3 5% 6% 31%	134484
Transparency	Day	50% 7% 13% 19% 9% 1	141679
	Night	53% 7% 12% 18% 9% 1	139127
Seeing	Day	22% 12% 30% 23% 10% 2	16640
	Night	23% 8% 30% 29% 9% 1	25512

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	16% 16% 6% 10% 5% 3 3 3 5% 5% 28%	4661
	11th to 20th	Day	13% 16% 6% 14% 7% 5% 4 4 4 5% 22%	4650
	21st to end	Day	9% 12% 7% 11% 6% 5% 4 3 5% 6% 31%	5124
February	1st to 10th	Day	13% 16% 4 11% 6% 5% 5% 3 4 5% 28%	1764
	11th to 20th	Day	14% 14% 4 11% 6% 5% 4 3 4 6% 27%	1978
	21st to end	Day	16% 14% 4 10% 6% 4 4 2 5% 5% 29%	1730
March	1st to 10th	Day	23% 12% 5% 9% 6% 4 4 3 4 5% 27%	4576
	11th to 20th	Day	12% 14% 4 9% 5% 4 4 4 5% 6% 33%	4751
	21st to end	Day	19% 12% 3 8% 5% 4 4 3 4 4 34%	6102
April	1st to 10th	Day	22% 11% 4 7% 5% 4 4 3 4 5% 31%	2520
	11th to 20th	Day	22% 8% 2 6% 4 4 4 3 5% 5% 37%	2518
	21st to end	Day	23% 10% 2 7% 5% 3 4 4 5% 6% 31%	2730
May	1st to 10th	Day	27% 8% 3 7% 5% 5% 4 4 5% 6% 27%	8052
	11th to 20th	Day	21% 7% 2 7% 5% 4 4 4 5% 7% 34%	8221
	21st to end	Day	21% 8% 3 8% 5% 5% 4 3 5% 6% 32%	9060
June	1st to 10th	Day	21% 7% 3 6% 6% 5% 5% 4 6% 7% 30%	2940
	11th to 20th	Day	16% 7% 2 6% 5% 4 5% 4 6% 8% 36%	2940
	21st to end	Day	21% 9% 3 7% 5% 5% 6% 4 6% 7% 28%	2940
July	1st to 10th	Day	16% 6% 2 8% 5% 5% 6% 5% 6% 8% 33%	6500
	11th to 20th	Day	15% 5% 2 6% 5% 5% 6% 4 7% 9% 36%	6430
	21st to end	Day	11% 5% 2 5% 5% 5% 5% 4 6% 8% 44%	6926
August	1st to 10th	Day	15% 5% 2 7% 5% 5% 6% 5% 8% 9% 33%	4563
	11th to 20th	Day	19% 5% 2 6% 4 4 4 4 6% 10% 35%	4226
	21st to end	Day	18% 5% 2 5% 5% 4 4 3 6% 8% 40%	4312
September	1st to 10th	Day	14% 5% 2 5% 4 5% 5% 3 6% 8% 43%	2400
	11th to 20th	Day	14% 5% 2 6% 3 4 4 3 4 7% 48%	2280
	21st to end	Day	20% 6% 2 5% 4 3 4 4 5% 6% 41%	2200
October	1st to 10th	Day	20% 7% 2 6% 4 4 3 3 4 7% 38%	2112
	11th to 20th	Day	21% 9% 2 7% 6% 5% 5% 3 6% 6% 29%	1900
	21st to end	Day	25% 11% 3 7% 4 3 4 3 4 6% 30%	1980
November	1st to 10th	Day	17% 11% 3 8% 5% 4 5% 3 4 5% 34%	1851
	11th to 20th	Day	20% 11% 4 8% 4 5% 4 3 4 6% 31%	1822
	21st to end	Day	22% 15% 4 8% 4 5% 4 4 4 6% 26%	1680
December	1st to 10th	Day	22% 16% 5% 8% 6% 5% 4 3 4 3 24%	2680
	11th to 20th	Day	21% 13% 5% 9% 4 3 4 3 4 5% 29%	3066
	21st to end	Day	21% 14% 4 9% 5% 4 4 3 4 5% 26%	4048
January	1st to 10th	Night	15% 18% 6% 12% 6% 5% 4 3 4 4 23%	8234
	11th to 20th	Night	13% 20% 6% 15% 6% 5% 4 3 4 4 19%	8235
	21st to end	Night	9% 12% 5% 14% 8% 6% 5% 4 5% 6% 27%	9057
February	1st to 10th	Night	13% 15% 4 11% 6% 5% 4 4 5% 6% 28%	2855
	11th to 20th	Night	14% 14% 5% 11% 7% 4 4 3 5% 4 29%	2527
	21st to end	Night	15% 13% 4 8% 6% 5% 5% 2 4 5% 32%	2076
March	1st to 10th	Night	25% 12% 4 11% 5% 4 4 2 4 4 25%	5484
	11th to 20th	Night	16% 13% 4 8% 6% 4 4 4 5% 7% 29%	5423
	21st to end	Night	17% 11% 4 9% 5% 4 5% 3 4 5% 31%	5072
April	1st to 10th	Night	24% 11% 3 6% 5% 4 4 3 4 6% 30%	2100
	11th to 20th	Night	21% 9% 2 7% 5% 4 4 4 5% 6% 35%	2050
	21st to end	Night	23% 9% 2 5% 4 2 4 3 4 6% 36%	1890
May	1st to 10th	Night	24% 9% 3 7% 4 5% 5% 4 5% 6% 27%	4902
	11th to 20th	Night	22% 6% 2 7% 5% 4 5% 4 5% 7% 33%	4639
	21st to end	Night	21% 8% 3 7% 5% 4 4 4 4 7% 33%	5114
June	1st to 10th	Night	20% 7% 2 6% 3 4 5% 4 6% 8% 35%	1680
	11th to 20th	Night	20% 6% 2 6% 4 5% 4 4 7% 6% 36%	1680
	21st to end	Night	20% 7% 3 6% 5% 4 4 4 5% 8% 33%	1680
July	1st to 10th	Night	14% 5% 2 7% 5% 6% 6% 5% 8% 9% 33%	3680
	11th to 20th	Night	17% 5% 2 6% 4 4 4 3 6% 7% 41%	3640
	21st to end	Night	12% 4 2 6% 4 4 5% 4 6% 7% 46%	3926
August	1st to 10th	Night	15% 5% 3 8% 6% 5% 5% 4 5% 7% 38%	2586
	11th to 20th	Night	18% 6% 2 7% 4 4 4 3 6% 6% 39%	2787
	21st to end	Night	21% 6% 3 7% 5% 3 4 3 4 6% 39%	3586
September	1st to 10th	Night	13% 4 2 6% 4 4 4 4 5% 7% 46%	2000
	11th to 20th	Night	15% 4 2 4 4 3 3 4 5% 5% 51%	2119
	21st to end	Night	18% 6% 2 5% 4 4 4 3 4 6% 45%	2200
October	1st to 10th	Night	18% 7% 2 7% 4 5% 4 3 4 4 42%	2285
	11th to 20th	Night	22% 8% 2 7% 4 4 4 3 4 6% 36%	2499
	21st to end	Night	25% 8% 3 7% 4 4 4 3 5% 6% 32%	2860
November	1st to 10th	Night	20% 10% 3 7% 5% 4 4 3 4 5% 34%	2667
	11th to 20th	Night	20% 10% 3 8% 5% 4 4 4 5% 5% 32%	2793
	21st to end	Night	24% 13% 4 8% 5% 4 4 2 4 5% 27%	2940
December	1st to 10th	Night	17% 15% 5% 10% 7% 6% 4 4 5% 5% 22%	4720
	11th to 20th	Night	25% 12% 4 9% 5% 4 4 3 4 4 27%	5348
	21st to end	Night	24% 16% 5% 9% 4 3 3 3 4 5% 26%	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	59% 6% 12% 17% 5%	4662
	11th to 20th	Day	64% 6% 8% 13% 7% 1	4680
	21st to end	Day	53% 6% 9% 17% 13% 1	5124
February	1st to 10th	Day	59% 5% 10% 17% 7% 2	1764
	11th to 20th	Day	57% 6% 13% 14% 10% 1	1987
	21st to end	Day	58% 5% 9% 17% 9% 2	1730
March	1st to 10th	Day	59% 7% 10% 11% 10% 3	4579
	11th to 20th	Day	50% 8% 17% 12% 12% 1	4751
	21st to end	Day	53% 6% 7% 17% 15% 3	6102
April	1st to 10th	Day	54% 6% 10% 16% 11% 2	2520
	11th to 20th	Day	48% 7% 11% 20% 12% 2	2518
	21st to end	Day	52% 7% 10% 17% 12% 3	2730
May	1st to 10th	Day	56% 6% 10% 17% 9% 1	8064
	11th to 20th	Day	47% 9% 17% 18% 8% 2	8225
	21st to end	Day	50% 8% 11% 18% 12% 2	9061
June	1st to 10th	Day	49% 9% 12% 19% 9% 1	2940
	11th to 20th	Day	43% 9% 14% 22% 11% 2	2940
	21st to end	Day	53% 9% 12% 16% 9% 1	2940
July	1st to 10th	Day	46% 8% 15% 23% 8%	6430
	11th to 20th	Day	41% 9% 17% 26% 7%	6355
	21st to end	Day	36% 7% 16% 31% 9%	6728
August	1st to 10th	Day	43% 11% 18% 20% 7%	4549
	11th to 20th	Day	42% 10% 21% 21% 5%	4267
	21st to end	Day	42% 9% 16% 20% 13% 1	4312
September	1st to 10th	Day	37% 8% 18% 25% 11% 1	2400
	11th to 20th	Day	36% 7% 16% 30% 11% 1	2280
	21st to end	Day	43% 7% 15% 25% 11%	2200
October	1st to 10th	Day	45% 7% 14% 26% 7%	3437
	11th to 20th	Day	47% 8% 18% 23% 4	3077
	21st to end	Day	46% 7% 19% 20% 7% 1	3180
November	1st to 10th	Day	51% 8% 13% 19% 8% 1	1851
	11th to 20th	Day	55% 6% 12% 17% 9%	1822
	21st to end	Day	61% 7% 12% 15% 4	1680
December	1st to 10th	Day	66% 4 9% 15% 5%	2680
	11th to 20th	Day	60% 4 9% 16% 11%	3066
	21st to end	Day	60% 7% 10% 14% 9%	4048
January	1st to 10th	Night	65% 6% 10% 13% 5%	8234
	11th to 20th	Night	68% 7% 9% 11% 4	8280
	21st to end	Night	57% 7% 9% 14% 13%	9057
February	1st to 10th	Night	57% 6% 11% 16% 9% 1	2855
	11th to 20th	Night	57% 6% 10% 15% 10% 1	2529
	21st to end	Night	54% 5% 10% 17% 12% 2	2076
March	1st to 10th	Night	63% 5% 9% 11% 10% 3	5494
	11th to 20th	Night	53% 8% 13% 14% 10% 2	5424
	21st to end	Night	54% 6% 8% 21% 9% 2	5072
April	1st to 10th	Night	54% 5% 11% 16% 13% 2	2100
	11th to 20th	Night	49% 7% 10% 18% 14% 2	2050
	21st to end	Night	49% 6% 9% 19% 14% 3	1890
May	1st to 10th	Night	55% 7% 11% 17% 8% 1	4908
	11th to 20th	Night	48% 8% 13% 20% 9% 1	4640
	21st to end	Night	50% 7% 10% 17% 15% 1	5115
June	1st to 10th	Night	44% 8% 14% 19% 14% 1	1680
	11th to 20th	Night	44% 8% 13% 20% 12% 3	1680
	21st to end	Night	48% 9% 13% 17% 13% 1	1680
July	1st to 10th	Night	45% 8% 19% 20% 7%	3640
	11th to 20th	Night	41% 8% 18% 26% 7%	3592
	21st to end	Night	36% 8% 18% 27% 11%	3809
August	1st to 10th	Night	45% 9% 15% 24% 7%	2576
	11th to 20th	Night	44% 8% 18% 22% 7%	2812
	21st to end	Night	46% 7% 13% 21% 12% 1	3586
September	1st to 10th	Night	37% 8% 16% 26% 13% 1	2000
	11th to 20th	Night	34% 6% 17% 31% 10% 1	2119
	21st to end	Night	41% 7% 11% 27% 14%	2200
October	1st to 10th	Night	49% 5% 14% 23% 9%	3740
	11th to 20th	Night	44% 7% 16% 28% 5%	4061
	21st to end	Night	45% 6% 17% 19% 11% 2	4610
November	1st to 10th	Night	52% 7% 14% 20% 6% 1	2667
	11th to 20th	Night	53% 7% 13% 17% 9% 1	2793
	21st to end	Night	61% 6% 12% 14% 7%	2940
December	1st to 10th	Night	64% 7% 13% 12% 4	4720
	11th to 20th	Night	62% 5% 8% 16% 9%	5348
	21st to end	Night	63% 5% 7% 16% 9% 1	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	25% 14% 34% 22% 4	220
	11th to 20th	Day	27% 15% 30% 20% 6% 1	220
	21st to end	Day	17% 12% 36% 27% 7% 2	242
February	1st to 10th	Day	23% 16% 40% 17% 4	264
	11th to 20th	Day	23% 13% 35% 25% 3	466
	21st to end	Day	22% 15% 37% 22% 4	446
March	1st to 10th	Day	26% 14% 31% 24% 6%	540
	11th to 20th	Day	22% 18% 34% 20% 5% 1	540
	21st to end	Day	26% 16% 30% 19% 8% 2	594
April	1st to 10th	Day	29% 14% 27% 24% 7%	540
	11th to 20th	Day	29% 16% 28% 19% 6% 2	532
	21st to end	Day	28% 14% 34% 16% 6% 2	540
May	1st to 10th	Day	28% 13% 34% 17% 8% 1	543
	11th to 20th	Day	19% 13% 31% 24% 10% 2	567
	21st to end	Day	22% 14% 35% 18% 9% 1	617
June	1st to 10th	Day	20% 14% 31% 25% 9% 2	570
	11th to 20th	Day	18% 13% 31% 23% 13% 2	570
	21st to end	Day	21% 10% 29% 25% 13% 2	570
July	1st to 10th	Day	15% 8% 30% 28% 16% 3	565
	11th to 20th	Day	16% 10% 30% 30% 13% 3	544
	21st to end	Day	14% 7% 29% 31% 16% 3	576
August	1st to 10th	Day	15% 7% 23% 32% 19% 3	526
	11th to 20th	Day	15% 5% 21% 35% 18% 7%	519
	21st to end	Day	16% 8% 28% 22% 18% 8%	583
September	1st to 10th	Day	15% 8% 31% 25% 15% 5%	530
	11th to 20th	Day	14% 8% 23% 28% 19% 8%	530
	21st to end	Day	19% 9% 26% 26% 14% 5%	530
October	1st to 10th	Day	22% 10% 28% 25% 13% 3	530
	11th to 20th	Day	25% 11% 31% 21% 10% 2	475
	21st to end	Day	31% 9% 32% 20% 8%	462
November	1st to 10th	Day	29% 14% 29% 21% 7%	425
	11th to 20th	Day	27% 14% 29% 24% 6%	362
	21st to end	Day	32% 17% 26% 19% 5%	220
December	1st to 10th	Day	33% 10% 27% 19% 7% 3	220
	11th to 20th	Day	29% 17% 30% 21% 2 1	220
	21st to end	Day	29% 17% 31% 14% 7% 2	242
January	1st to 10th	Night	29% 8% 32% 26% 5%	840
	11th to 20th	Night	30% 9% 31% 24% 7%	840
	21st to end	Night	17% 7% 31% 36% 7% 1	924
February	1st to 10th	Night	19% 8% 37% 29% 7% 1	840
	11th to 20th	Night	20% 12% 38% 25% 4 1	823
	21st to end	Night	22% 9% 34% 29% 6%	692
March	1st to 10th	Night	25% 10% 31% 30% 4	840
	11th to 20th	Night	22% 12% 34% 26% 5%	840
	21st to end	Night	22% 11% 34% 26% 6% 1	924
April	1st to 10th	Night	28% 11% 29% 26% 6%	840
	11th to 20th	Night	25% 11% 32% 27% 4	806
	21st to end	Night	28% 10% 32% 23% 7%	630
May	1st to 10th	Night	26% 10% 30% 26% 7%	506
	11th to 20th	Night	21% 7% 31% 33% 7%	414
	21st to end	Night	22% 7% 38% 25% 8%	455
June	1st to 10th	Night	22% 5% 29% 35% 9% 1	420
	11th to 20th	Night	21% 4 27% 37% 9%	420
	21st to end	Night	21% 5% 24% 39% 11%	420
July	1st to 10th	Night	13% 4 29% 40% 13% 1	410
	11th to 20th	Night	14% 4 26% 42% 14% 1	398
	21st to end	Night	16% 3 22% 44% 14% 1	438
August	1st to 10th	Night	12% 5% 16% 45% 21% 1	398
	11th to 20th	Night	15% 4 21% 39% 20% 2	530
	21st to end	Night	18% 5% 24% 33% 19% 1	880
September	1st to 10th	Night	16% 5% 26% 39% 14% 1	800
	11th to 20th	Night	17% 5% 22% 34% 21% 2	800
	21st to end	Night	19% 7% 26% 31% 16% 2	800
October	1st to 10th	Night	21% 7% 30% 31% 10% 1	800
	11th to 20th	Night	24% 8% 29% 30% 9% 1	800
	21st to end	Night	29% 8% 31% 26% 5%	880
November	1st to 10th	Night	26% 9% 30% 27% 6% 1	820
	11th to 20th	Night	24% 8% 35% 22% 10% 1	840
	21st to end	Night	31% 10% 28% 24% 6%	840
December	1st to 10th	Night	29% 9% 30% 26% 6%	840
	11th to 20th	Night	27% 11% 33% 22% 7% 1	840
	21st to end	Night	32% 11% 27% 23% 6%	924

Page generated at 2026-07-13 03:14:48. Version ac07

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