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 2005-11-05 to 2024-10-14.

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 7% 5% 4 4 4 5% 7% 33%	101348
	Night	19% 10% 3 8% 5% 4 4 3 5% 5% 33%	97226
Transparency	Day	49% 9% 14% 19% 9% 1	101109
	Night	52% 8% 13% 18% 9% 1	97090
Seeing	Day	22% 11% 30% 24% 11% 3	14485
	Night	23% 8% 30% 30% 9% 1	23338

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	17% 14% 5% 9% 5% 4 4 3 4 5% 29%	2517
	11th to 20th	Day	14% 14% 6% 10% 6% 4 5% 4 4 5% 29%	2520
	21st to end	Day	14% 13% 6% 10% 6% 5% 4 4 6% 5% 27%	2772
February	1st to 10th	Day	13% 17% 4 10% 6% 5% 5% 3 4 5% 27%	1596
	11th to 20th	Day	14% 14% 5% 12% 6% 5% 4 3 4 6% 27%	1784
	21st to end	Day	17% 15% 4 10% 6% 4 4 2 5% 5% 28%	1570
March	1st to 10th	Day	20% 10% 5% 8% 5% 5% 4 3 4 5% 29%	3116
	11th to 20th	Day	14% 17% 5% 10% 5% 4 4 4 4 6% 28%	3246
	21st to end	Day	14% 11% 4 7% 5% 4 4 3 4 5% 38%	4166
April	1st to 10th	Day	22% 11% 4 7% 5% 4 4 3 4 5% 31%	2280
	11th to 20th	Day	21% 8% 2 6% 4 4 4 3 5% 5% 37%	2276
	21st to end	Day	23% 11% 2 7% 5% 3 4 4 5% 6% 31%	2470
May	1st to 10th	Day	21% 7% 3 7% 5% 4 3 3 5% 6% 34%	4325
	11th to 20th	Day	16% 7% 2 7% 5% 4 5% 4 6% 8% 34%	4398
	21st to end	Day	17% 6% 3 7% 5% 5% 5% 4 6% 7% 35%	4837
June	1st to 10th	Day	21% 8% 3 6% 6% 5% 5% 4 6% 7% 30%	2660
	11th to 20th	Day	16% 7% 3 6% 5% 4 5% 4 6% 8% 36%	2660
	21st to end	Day	21% 9% 3 7% 5% 5% 6% 4 6% 6% 28%	2660
July	1st to 10th	Day	13% 6% 2 8% 5% 5% 6% 5% 6% 8% 35%	4440
	11th to 20th	Day	16% 5% 2 6% 5% 5% 6% 5% 7% 9% 34%	4440
	21st to end	Day	13% 5% 2 6% 5% 4 5% 4 6% 7% 43%	4814
August	1st to 10th	Day	15% 5% 2 7% 5% 5% 6% 5% 8% 9% 32%	4423
	11th to 20th	Day	19% 5% 2 6% 4 4 4 4 6% 10% 35%	4095
	21st to end	Day	18% 5% 2 5% 5% 4 5% 3 6% 8% 40%	4180
September	1st to 10th	Day	14% 5% 2 5% 4 5% 5% 4 6% 8% 42%	2280
	11th to 20th	Day	14% 6% 2 6% 3 4 4 3 4 7% 48%	2166
	21st to end	Day	20% 7% 2 6% 3 3 4 3 5% 6% 41%	2090
October	1st to 10th	Day	21% 8% 2 6% 4 4 4 3 4 6% 36%	2007
	11th to 20th	Day	22% 9% 2 7% 6% 5% 6% 3 6% 6% 28%	1740
	21st to end	Day	26% 11% 3 7% 4 3 4 3 4 6% 28%	1782
November	1st to 10th	Day	17% 11% 3 7% 5% 4 5% 3 4 6% 34%	1671
	11th to 20th	Day	21% 11% 4 8% 5% 5% 4 3 4 6% 30%	1649
	21st to end	Day	21% 15% 3 7% 4 5% 4 4 4 6% 27%	1520
December	1st to 10th	Day	26% 15% 4 7% 6% 4 4 3 4 4 25%	1520
	11th to 20th	Day	22% 14% 5% 10% 4 3 3 2 3 5% 27%	1906
	21st to end	Day	23% 18% 5% 10% 4 3 3 2 4 4 24%	2772
January	1st to 10th	Night	17% 17% 5% 9% 5% 4 4 4 4 4 26%	4429
	11th to 20th	Night	13% 15% 4 11% 7% 6% 5% 3 4 5% 27%	4440
	21st to end	Night	13% 14% 5% 12% 6% 5% 5% 4 5% 5% 26%	4884
February	1st to 10th	Night	14% 15% 4 10% 7% 5% 4 4 5% 6% 27%	2584
	11th to 20th	Night	14% 13% 5% 11% 7% 4 4 4 5% 5% 29%	2281
	21st to end	Night	16% 13% 4 8% 6% 5% 4 2 4 5% 32%	1884
March	1st to 10th	Night	24% 11% 4 7% 5% 3 4 3 4 5% 29%	3724
	11th to 20th	Night	19% 17% 5% 9% 6% 4 4 3 3 4 27%	3708
	21st to end	Night	15% 10% 4 9% 6% 4 5% 4 4 5% 35%	3466
April	1st to 10th	Night	24% 11% 3 6% 4 4 4 3 4 6% 30%	1900
	11th to 20th	Night	21% 9% 2 6% 5% 3 4 3 5% 6% 36%	1852
	21st to end	Night	23% 9% 3 6% 4 2 4 3 4 6% 35%	1710
May	1st to 10th	Night	22% 9% 3 8% 3 5% 5% 4 5% 5% 30%	2644
	11th to 20th	Night	21% 7% 2 6% 4 3 5% 3 6% 7% 35%	2495
	21st to end	Night	19% 6% 3 7% 5% 5% 4 4 5% 8% 35%	2738
June	1st to 10th	Night	20% 7% 2 6% 3 4 5% 4 7% 8% 34%	1520
	11th to 20th	Night	20% 6% 2 5% 4 4 4 4 7% 6% 37%	1520
	21st to end	Night	21% 7% 3 7% 4 4 4 5% 5% 8% 32%	1520
July	1st to 10th	Night	15% 5% 3 8% 6% 6% 6% 5% 7% 8% 32%	2520
	11th to 20th	Night	17% 5% 2 6% 4 4 4 3 7% 7% 39%	2520
	21st to end	Night	13% 4 2 5% 4 4 5% 4 6% 7% 46%	2739
August	1st to 10th	Night	15% 6% 3 8% 6% 5% 5% 4 5% 7% 37%	2506
	11th to 20th	Night	19% 7% 2 7% 4 4 4 3 6% 6% 38%	2700
	21st to end	Night	21% 6% 3 7% 5% 3 4 3 4 6% 39%	3476
September	1st to 10th	Night	13% 5% 3 6% 4 4 3 4 5% 7% 45%	1900
	11th to 20th	Night	16% 4 2 4 4 3 3 4 5% 6% 50%	2013
	21st to end	Night	18% 6% 2 5% 4 4 4 3 3 6% 44%	2090
October	1st to 10th	Night	18% 7% 2 7% 4 5% 4 3 4 4 40%	2171
	11th to 20th	Night	23% 8% 3 7% 4 4 4 3 5% 6% 34%	2292
	21st to end	Night	26% 8% 3 7% 4 4 4 3 4 6% 31%	2574
November	1st to 10th	Night	20% 10% 3 7% 5% 4 4 3 4 5% 35%	2407
	11th to 20th	Night	20% 10% 3 8% 5% 4 4 4 5% 5% 32%	2527
	21st to end	Night	24% 13% 4 7% 5% 4 4 3 3 5% 28%	2660
December	1st to 10th	Night	22% 14% 5% 9% 6% 5% 4 3 4 5% 23%	2660
	11th to 20th	Night	24% 13% 4 9% 5% 4 3 2 3 3 27%	3288
	21st to end	Night	25% 18% 5% 9% 3 3 3 2 3 4 25%	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	57% 8% 16% 15% 4	2518
	11th to 20th	Day	55% 9% 12% 18% 6%	2520
	21st to end	Day	55% 9% 12% 18% 6% 1	2772
February	1st to 10th	Day	60% 5% 11% 16% 7% 2	1596
	11th to 20th	Day	57% 6% 13% 13% 9% 1	1793
	21st to end	Day	58% 5% 10% 16% 8% 2	1570
March	1st to 10th	Day	54% 10% 13% 14% 8% 2	3119
	11th to 20th	Day	53% 10% 13% 12% 11% 2	3246
	21st to end	Day	46% 7% 9% 20% 14% 3	4166
April	1st to 10th	Day	55% 6% 10% 16% 11% 2	2280
	11th to 20th	Day	47% 7% 11% 21% 12% 2	2276
	21st to end	Day	53% 7% 10% 16% 12% 3	2470
May	1st to 10th	Day	47% 8% 14% 18% 12% 1	4339
	11th to 20th	Day	42% 12% 22% 15% 8% 1	4402
	21st to end	Day	43% 11% 12% 18% 14% 2	4837
June	1st to 10th	Day	50% 10% 13% 18% 9% 2	2660
	11th to 20th	Day	43% 9% 15% 21% 11% 2	2660
	21st to end	Day	53% 10% 12% 15% 9% 1	2660
July	1st to 10th	Day	44% 9% 16% 23% 9%	4370
	11th to 20th	Day	43% 10% 19% 22% 6%	4365
	21st to end	Day	39% 9% 15% 28% 9%	4661
August	1st to 10th	Day	44% 11% 18% 20% 7%	4409
	11th to 20th	Day	43% 10% 21% 21% 5%	4136
	21st to end	Day	42% 9% 16% 19% 14% 1	4180
September	1st to 10th	Day	37% 9% 18% 24% 11% 1	2280
	11th to 20th	Day	37% 7% 16% 29% 11% 1	2166
	21st to end	Day	44% 7% 15% 25% 10%	2090
October	1st to 10th	Day	47% 7% 12% 24% 8%	2007
	11th to 20th	Day	54% 9% 14% 18% 4	1741
	21st to end	Day	58% 7% 12% 16% 7% 1	1782
November	1st to 10th	Day	50% 8% 14% 19% 8% 1	1671
	11th to 20th	Day	56% 6% 13% 16% 9%	1649
	21st to end	Day	58% 8% 13% 16% 4	1520
December	1st to 10th	Day	64% 5% 11% 14% 5%	1520
	11th to 20th	Day	61% 4 11% 18% 6%	1906
	21st to end	Day	64% 7% 11% 11% 7%	2772
January	1st to 10th	Night	59% 8% 15% 13% 5%	4429
	11th to 20th	Night	56% 9% 14% 16% 4 1	4440
	21st to end	Night	58% 9% 12% 13% 7%	4884
February	1st to 10th	Night	58% 6% 11% 15% 8% 1	2584
	11th to 20th	Night	57% 7% 11% 14% 10% 1	2283
	21st to end	Night	54% 5% 11% 16% 12% 2	1884
March	1st to 10th	Night	57% 7% 12% 14% 8% 3	3734
	11th to 20th	Night	58% 8% 9% 13% 9% 2	3709
	21st to end	Night	49% 7% 10% 21% 10% 3	3466
April	1st to 10th	Night	54% 5% 11% 16% 13% 2	1900
	11th to 20th	Night	48% 7% 11% 19% 14% 2	1852
	21st to end	Night	50% 6% 9% 18% 14% 3	1710
May	1st to 10th	Night	51% 9% 13% 15% 8% 2	2650
	11th to 20th	Night	43% 11% 16% 17% 10% 2	2496
	21st to end	Night	45% 9% 12% 17% 16% 1	2739
June	1st to 10th	Night	44% 9% 16% 18% 12% 1	1520
	11th to 20th	Night	43% 9% 13% 20% 12% 4	1520
	21st to end	Night	48% 9% 13% 16% 13% 1	1520
July	1st to 10th	Night	47% 9% 17% 18% 9% 1	2480
	11th to 20th	Night	42% 9% 19% 23% 6%	2472
	21st to end	Night	35% 9% 20% 24% 11%	2651
August	1st to 10th	Night	46% 9% 15% 24% 6%	2496
	11th to 20th	Night	45% 8% 19% 22% 7%	2725
	21st to end	Night	46% 7% 13% 21% 12% 1	3476
September	1st to 10th	Night	37% 8% 16% 25% 13% 1	1900
	11th to 20th	Night	35% 7% 17% 30% 10% 1	2013
	21st to end	Night	41% 7% 11% 27% 13%	2090
October	1st to 10th	Night	47% 6% 11% 23% 12%	2171
	11th to 20th	Night	50% 8% 14% 21% 6%	2296
	21st to end	Night	55% 7% 12% 17% 9%	2574
November	1st to 10th	Night	52% 7% 14% 19% 7% 1	2407
	11th to 20th	Night	53% 8% 13% 16% 9% 1	2527
	21st to end	Night	59% 6% 13% 14% 7%	2660
December	1st to 10th	Night	64% 6% 12% 13% 5%	2660
	11th to 20th	Night	61% 5% 10% 16% 7%	3288
	21st to end	Night	65% 5% 9% 16% 5% 1	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	25% 14% 33% 24% 4 1	180
	11th to 20th	Day	26% 13% 31% 23% 6% 2	180
	21st to end	Day	17% 8% 39% 27% 8% 2	198
February	1st to 10th	Day	26% 16% 40% 15% 2	216
	11th to 20th	Day	23% 11% 36% 27% 3	392
	21st to end	Day	23% 15% 34% 24% 4	382
March	1st to 10th	Day	23% 12% 31% 27% 7%	460
	11th to 20th	Day	20% 18% 33% 21% 6% 1	460
	21st to end	Day	25% 14% 30% 21% 9% 2	506
April	1st to 10th	Day	27% 11% 27% 26% 8%	460
	11th to 20th	Day	26% 16% 28% 21% 7% 2	452
	21st to end	Day	28% 13% 35% 16% 7% 2	460
May	1st to 10th	Day	25% 12% 34% 18% 9% 1	463
	11th to 20th	Day	17% 11% 33% 25% 11% 3	487
	21st to end	Day	20% 13% 34% 20% 10% 1	529
June	1st to 10th	Day	20% 12% 30% 26% 9% 2	490
	11th to 20th	Day	16% 12% 30% 26% 14% 2	490
	21st to end	Day	22% 10% 27% 25% 14% 2	490
July	1st to 10th	Day	15% 7% 28% 29% 18% 3	485
	11th to 20th	Day	16% 9% 28% 31% 13% 3	484
	21st to end	Day	15% 6% 27% 33% 17% 4	532
August	1st to 10th	Day	16% 8% 22% 31% 20% 3	486
	11th to 20th	Day	15% 5% 20% 34% 18% 7%	479
	21st to end	Day	15% 7% 29% 22% 18% 9%	539
September	1st to 10th	Day	16% 8% 31% 26% 14% 6%	490
	11th to 20th	Day	15% 9% 22% 28% 20% 7%	490
	21st to end	Day	19% 8% 27% 26% 14% 6%	490
October	1st to 10th	Day	23% 10% 27% 24% 13% 3	490
	11th to 20th	Day	27% 9% 32% 21% 10% 2	417
	21st to end	Day	31% 9% 31% 20% 9%	396
November	1st to 10th	Day	27% 12% 30% 23% 8% 1	365
	11th to 20th	Day	26% 13% 29% 24% 7%	309
	21st to end	Day	28% 17% 27% 21% 6% 1	180
December	1st to 10th	Day	34% 9% 26% 20% 8% 3	180
	11th to 20th	Day	29% 16% 28% 23% 2 2	180
	21st to end	Day	31% 18% 27% 16% 7% 1	198
January	1st to 10th	Night	29% 8% 32% 26% 5%	760
	11th to 20th	Night	28% 8% 33% 25% 6%	760
	21st to end	Night	18% 6% 32% 36% 7% 1	836
February	1st to 10th	Night	20% 8% 38% 28% 6% 1	760
	11th to 20th	Night	20% 11% 37% 26% 5% 1	743
	21st to end	Night	22% 9% 34% 29% 6%	628
March	1st to 10th	Night	24% 9% 31% 32% 4	760
	11th to 20th	Night	22% 11% 34% 26% 5% 1	760
	21st to end	Night	21% 10% 34% 27% 6% 1	836
April	1st to 10th	Night	28% 10% 28% 28% 6%	760
	11th to 20th	Night	25% 11% 32% 27% 5%	728
	21st to end	Night	27% 11% 32% 24% 7%	570
May	1st to 10th	Night	26% 9% 31% 27% 7%	458
	11th to 20th	Night	21% 6% 31% 33% 7%	374
	21st to end	Night	22% 6% 38% 26% 8%	411
June	1st to 10th	Night	22% 5% 27% 35% 9% 1	380
	11th to 20th	Night	21% 4 26% 38% 10% 1	380
	21st to end	Night	22% 4 24% 38% 12%	380
July	1st to 10th	Night	14% 4 28% 40% 14% 1	370
	11th to 20th	Night	14% 3 25% 43% 14% 1	368
	21st to end	Night	17% 3 21% 44% 15% 1	416
August	1st to 10th	Night	13% 5% 16% 44% 21% 1	378
	11th to 20th	Night	16% 4 20% 39% 20% 2	503
	21st to end	Night	18% 4 25% 33% 19% 1	836
September	1st to 10th	Night	16% 4 26% 39% 13% 1	760
	11th to 20th	Night	17% 5% 22% 34% 20% 2	760
	21st to end	Night	19% 8% 26% 30% 16% 2	760
October	1st to 10th	Night	22% 7% 30% 31% 10% 1	760
	11th to 20th	Night	25% 8% 28% 29% 9% 1	735
	21st to end	Night	30% 8% 31% 26% 5%	792
November	1st to 10th	Night	25% 9% 31% 27% 7% 1	740
	11th to 20th	Night	25% 8% 34% 22% 10% 1	760
	21st to end	Night	31% 9% 29% 25% 6% 1	760
December	1st to 10th	Night	31% 8% 29% 25% 6%	760
	11th to 20th	Night	26% 10% 33% 23% 7% 1	760
	21st to end	Night	33% 10% 27% 24% 6%	836

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