Pointe Sainte-Foy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pointe Sainte-Foy clear sky chart from 2005-11-06 to 2024-03-28.

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% 4 7% 6% 3 5% 5% 5% 7% 31%	78351
	Night	19% 11% 4 8% 6% 3 4 4 5% 6% 30%	81636
Transparency	Day	52% 7% 13% 19% 8% 1	78056
	Night	55% 6% 11% 18% 8% 1	81466
Seeing	Day	23% 14% 29% 22% 10% 2	14314
	Night	24% 11% 29% 28% 8% 1	23038

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% 17% 6% 10% 8% 4 4 4 4 5% 22%	2517
	11th to 20th	Day	10% 14% 7% 15% 8% 4 4 3 4 4 27%	2520
	21st to end	Day	10% 12% 6% 8% 7% 4 5% 5% 5% 6% 33%	2772
February	1st to 10th	Day	11% 13% 6% 11% 7% 4 4 5% 5% 6% 26%	1520
	11th to 20th	Day	14% 13% 6% 9% 6% 4 5% 5% 5% 6% 27%	1835
	21st to end	Day	13% 13% 5% 9% 8% 3 4 5% 4 7% 28%	1570
March	1st to 10th	Day	15% 12% 5% 7% 5% 3 4 4 4 7% 33%	1897
	11th to 20th	Day	16% 12% 6% 6% 5% 4 5% 5% 4 6% 31%	1990
	21st to end	Day	16% 10% 4 7% 5% 3 5% 5% 5% 6% 34%	2393
April	1st to 10th	Day	22% 11% 4 7% 6% 4 5% 4 4 5% 29%	2160
	11th to 20th	Day	20% 7% 3 5% 5% 3 4 4 4 6% 38%	2217
	21st to end	Day	24% 8% 3 6% 6% 3 4 4 4 6% 31%	2340
May	1st to 10th	Day	22% 7% 3 6% 5% 3 4 4 5% 6% 34%	2394
	11th to 20th	Day	19% 6% 3 6% 6% 4 5% 5% 5% 7% 34%	2478
	21st to end	Day	20% 6% 3 7% 5% 4 6% 6% 5% 6% 33%	2738
June	1st to 10th	Day	20% 6% 2 6% 7% 4 6% 6% 7% 9% 27%	2700
	11th to 20th	Day	19% 6% 3 5% 5% 3 5% 5% 6% 8% 35%	2700
	21st to end	Day	22% 8% 4 6% 7% 3 6% 5% 5% 7% 27%	2700
July	1st to 10th	Day	15% 6% 3 5% 7% 4 6% 6% 7% 10% 33%	2545
	11th to 20th	Day	15% 6% 3 5% 5% 4 6% 6% 7% 10% 32%	2520
	21st to end	Day	14% 7% 3 6% 6% 4 5% 6% 7% 8% 33%	2744
August	1st to 10th	Day	16% 6% 3 5% 6% 4 7% 6% 7% 10% 28%	2498
	11th to 20th	Day	14% 7% 3 6% 6% 3 5% 4 6% 8% 37%	2304
	21st to end	Day	16% 6% 2 6% 5% 3 5% 5% 5% 7% 39%	2462
September	1st to 10th	Day	16% 7% 3 6% 5% 3 4 5% 6% 9% 37%	2160
	11th to 20th	Day	18% 6% 2 4 3 3 3 4 5% 8% 45%	2003
	21st to end	Day	20% 6% 3 6% 5% 3 4 4 5% 7% 38%	1980
October	1st to 10th	Day	20% 8% 2 6% 6% 3 5% 5% 5% 7% 33%	1976
	11th to 20th	Day	24% 7% 4 8% 6% 3 5% 5% 6% 7% 24%	1650
	21st to end	Day	28% 10% 4 7% 6% 3 4 5% 4 5% 24%	1782
November	1st to 10th	Day	20% 9% 3 7% 7% 3 5% 4 4 5% 32%	1671
	11th to 20th	Day	22% 11% 5% 8% 6% 4 5% 4 5% 4 25%	1710
	21st to end	Day	22% 16% 5% 8% 5% 3 5% 4 4 5% 23%	1374
December	1st to 10th	Day	24% 15% 5% 8% 6% 4 5% 4 4 3 21%	1330
	11th to 20th	Day	21% 13% 5% 8% 8% 4 3 4 4 5% 25%	1668
	21st to end	Day	23% 16% 5% 8% 6% 3 4 4 3 5% 24%	2533
January	1st to 10th	Night	15% 19% 6% 12% 8% 3 4 3 3 4 22%	4429
	11th to 20th	Night	12% 15% 5% 12% 9% 4 5% 5% 5% 5% 23%	4440
	21st to end	Night	11% 13% 5% 9% 8% 5% 6% 5% 6% 6% 25%	4884
February	1st to 10th	Night	12% 13% 6% 10% 8% 4 5% 5% 5% 6% 26%	2660
	11th to 20th	Night	14% 15% 7% 9% 7% 4 4 4 5% 5% 26%	2226
	21st to end	Night	15% 13% 5% 9% 6% 4 4 4 5% 6% 30%	1884
March	1st to 10th	Night	16% 13% 5% 8% 6% 3 5% 5% 4 6% 30%	2270
	11th to 20th	Night	18% 13% 3 8% 6% 5% 5% 4 5% 5% 28%	2189
	21st to end	Night	18% 11% 4 6% 6% 3 4 4 4 6% 35%	2114
April	1st to 10th	Night	23% 12% 5% 6% 5% 4 4 5% 5% 5% 27%	1800
	11th to 20th	Night	20% 9% 2 6% 5% 3 4 5% 5% 6% 35%	1692
	21st to end	Night	24% 9% 4 7% 5% 2 3 3 4 5% 34%	1620
May	1st to 10th	Night	23% 7% 3 5% 6% 3 6% 4 5% 5% 32%	1581
	11th to 20th	Night	22% 8% 3 5% 6% 3 4 4 5% 6% 35%	1415
	21st to end	Night	22% 6% 2 6% 5% 3 5% 4 4 6% 37%	1532
June	1st to 10th	Night	22% 7% 3 5% 7% 4 5% 5% 7% 8% 28%	1260
	11th to 20th	Night	20% 6% 2 5% 6% 3 4 4 5% 8% 36%	1260
	21st to end	Night	21% 8% 5% 6% 5% 4 5% 4 5% 7% 30%	1260
July	1st to 10th	Night	16% 6% 3 5% 5% 4 5% 5% 6% 8% 37%	1410
	11th to 20th	Night	17% 6% 3 6% 6% 2 5% 4 6% 9% 35%	1440
	21st to end	Night	15% 6% 2 7% 6% 4 5% 6% 7% 8% 35%	1574
August	1st to 10th	Night	16% 4 2 4 6% 4 6% 6% 6% 11% 37%	1432
	11th to 20th	Night	15% 7% 3 6% 7% 4 6% 5% 6% 9% 33%	1587
	21st to end	Night	16% 5% 2 6% 6% 3 5% 5% 5% 8% 39%	1890
September	1st to 10th	Night	18% 6% 3 5% 6% 3 4 4 5% 7% 39%	1800
	11th to 20th	Night	18% 6% 3 5% 4 3 4 4 4 6% 44%	1957
	21st to end	Night	19% 6% 3 4 5% 3 4 4 5% 6% 40%	1980
October	1st to 10th	Night	18% 7% 2 5% 5% 3 5% 5% 6% 6% 37%	1983
	11th to 20th	Night	25% 9% 4 6% 6% 3 4 5% 4 5% 30%	2309
	21st to end	Night	25% 10% 3 7% 5% 2 4 5% 5% 6% 28%	2574
November	1st to 10th	Night	19% 10% 4 6% 6% 4 5% 4 5% 6% 31%	2407
	11th to 20th	Night	20% 9% 4 9% 6% 3 4 4 5% 6% 30%	2470
	21st to end	Night	22% 14% 5% 7% 6% 3 5% 4 5% 5% 24%	2800
December	1st to 10th	Night	23% 15% 5% 9% 7% 4 6% 4 4 4 19%	2850
	11th to 20th	Night	21% 13% 5% 10% 7% 3 4 4 4 5% 24%	3531
	21st to end	Night	25% 19% 4 7% 5% 2 3 3 3 3 24%	5126

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	64% 6% 11% 15% 4 1	2518
	11th to 20th	Day	61% 7% 9% 17% 5% 1	2520
	21st to end	Day	51% 6% 11% 23% 9%	2772
February	1st to 10th	Day	59% 5% 12% 15% 8% 2	1520
	11th to 20th	Day	59% 5% 13% 13% 9% 1	1844
	21st to end	Day	56% 5% 10% 18% 8% 2	1570
March	1st to 10th	Day	53% 6% 10% 18% 12% 2	1900
	11th to 20th	Day	54% 6% 10% 17% 12% 1	1990
	21st to end	Day	51% 5% 11% 18% 11% 3	2393
April	1st to 10th	Day	58% 4 11% 13% 10% 3	2160
	11th to 20th	Day	47% 4 11% 24% 12% 2	2217
	21st to end	Day	55% 5% 10% 16% 11% 2	2340
May	1st to 10th	Day	49% 6% 12% 17% 14% 2	2394
	11th to 20th	Day	49% 7% 11% 20% 12% 1	2482
	21st to end	Day	51% 7% 11% 19% 11% 1	2738
June	1st to 10th	Day	50% 10% 12% 18% 8% 1	2700
	11th to 20th	Day	47% 7% 13% 20% 11% 2	2700
	21st to end	Day	56% 8% 11% 16% 9%	2700
July	1st to 10th	Day	44% 11% 16% 23% 6%	2475
	11th to 20th	Day	43% 10% 17% 22% 7%	2445
	21st to end	Day	48% 9% 17% 20% 7%	2591
August	1st to 10th	Day	48% 11% 19% 20% 3	2484
	11th to 20th	Day	43% 8% 18% 21% 9%	2304
	21st to end	Day	43% 9% 13% 25% 9%	2462
September	1st to 10th	Day	43% 8% 16% 23% 10%	2160
	11th to 20th	Day	38% 5% 18% 29% 10%	2003
	21st to end	Day	46% 6% 14% 26% 9%	1980
October	1st to 10th	Day	49% 7% 13% 24% 8%	1976
	11th to 20th	Day	57% 8% 16% 16% 2	1650
	21st to end	Day	62% 7% 9% 17% 5% 1	1782
November	1st to 10th	Day	55% 6% 12% 19% 8%	1671
	11th to 20th	Day	60% 5% 10% 18% 6% 1	1710
	21st to end	Day	64% 6% 12% 12% 5% 1	1374
December	1st to 10th	Day	67% 5% 11% 13% 4	1330
	11th to 20th	Day	61% 5% 8% 18% 7%	1668
	21st to end	Day	62% 6% 11% 12% 6% 2	2533
January	1st to 10th	Night	66% 6% 10% 12% 5%	4429
	11th to 20th	Night	62% 5% 10% 19% 4 1	4440
	21st to end	Night	57% 6% 12% 17% 8% 1	4884
February	1st to 10th	Night	59% 5% 10% 17% 8% 1	2660
	11th to 20th	Night	60% 5% 11% 15% 9% 1	2228
	21st to end	Night	56% 5% 9% 16% 13% 1	1884
March	1st to 10th	Night	56% 6% 10% 16% 10% 2	2280
	11th to 20th	Night	57% 6% 9% 15% 11% 2	2190
	21st to end	Night	52% 5% 9% 19% 11% 4	2114
April	1st to 10th	Night	58% 4 9% 15% 11% 3	1800
	11th to 20th	Night	48% 6% 10% 21% 12% 2	1692
	21st to end	Night	54% 5% 8% 17% 14% 2	1620
May	1st to 10th	Night	53% 6% 9% 15% 14% 2	1581
	11th to 20th	Night	50% 6% 10% 17% 16% 2	1416
	21st to end	Night	49% 7% 10% 18% 15% 1	1533
June	1st to 10th	Night	52% 7% 13% 18% 9% 1	1260
	11th to 20th	Night	47% 7% 12% 20% 11% 3	1260
	21st to end	Night	53% 7% 12% 17% 11%	1260
July	1st to 10th	Night	44% 9% 18% 21% 9%	1370
	11th to 20th	Night	45% 8% 16% 23% 7% 1	1392
	21st to end	Night	47% 9% 17% 19% 8%	1486
August	1st to 10th	Night	39% 10% 19% 27% 5%	1422
	11th to 20th	Night	46% 9% 20% 19% 6%	1587
	21st to end	Night	43% 7% 13% 28% 9%	1890
September	1st to 10th	Night	44% 6% 14% 23% 11% 1	1800
	11th to 20th	Night	41% 6% 17% 27% 8% 1	1957
	21st to end	Night	44% 6% 11% 27% 12%	1980
October	1st to 10th	Night	46% 7% 10% 24% 11% 1	1983
	11th to 20th	Night	56% 7% 13% 20% 5%	2309
	21st to end	Night	57% 5% 13% 17% 7%	2574
November	1st to 10th	Night	54% 6% 13% 20% 6% 1	2407
	11th to 20th	Night	54% 7% 13% 17% 9%	2470
	21st to end	Night	62% 6% 11% 14% 6% 1	2800
December	1st to 10th	Night	68% 5% 11% 12% 4	2850
	11th to 20th	Night	62% 5% 9% 15% 8%	3532
	21st to end	Night	65% 5% 8% 15% 6% 1	5126

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	27% 19% 31% 17% 4 1	180
	11th to 20th	Day	28% 23% 31% 13% 5%	180
	21st to end	Day	15% 21% 37% 22% 4 1	198
February	1st to 10th	Day	24% 24% 34% 14% 3 1	180
	11th to 20th	Day	22% 20% 37% 17% 4	448
	21st to end	Day	22% 22% 29% 22% 5%	382
March	1st to 10th	Day	24% 19% 30% 21% 7% 1	460
	11th to 20th	Day	23% 18% 33% 18% 7% 2	460
	21st to end	Day	23% 16% 27% 22% 11% 1	490
April	1st to 10th	Day	27% 15% 29% 20% 9%	420
	11th to 20th	Day	25% 12% 30% 22% 9% 1	412
	21st to end	Day	29% 14% 32% 17% 6% 2	420
May	1st to 10th	Day	27% 17% 32% 18% 5% 1	423
	11th to 20th	Day	20% 13% 33% 23% 8% 2	447
	21st to end	Day	23% 18% 32% 19% 7% 1	498
June	1st to 10th	Day	23% 13% 30% 25% 9% 1	630
	11th to 20th	Day	22% 11% 27% 27% 13% 1	630
	21st to end	Day	26% 9% 27% 25% 12% 2	630
July	1st to 10th	Day	18% 12% 29% 26% 14% 2	470
	11th to 20th	Day	15% 10% 32% 29% 12% 2	444
	21st to end	Day	15% 9% 34% 28% 13% 2	488
August	1st to 10th	Day	18% 7% 27% 27% 16% 4	446
	11th to 20th	Day	18% 5% 28% 27% 18% 3	439
	21st to end	Day	22% 10% 26% 19% 15% 8%	495
September	1st to 10th	Day	18% 12% 26% 27% 14% 4	450
	11th to 20th	Day	20% 12% 28% 18% 18% 5%	450
	21st to end	Day	20% 13% 23% 23% 14% 6%	450
October	1st to 10th	Day	22% 13% 26% 25% 10% 3	450
	11th to 20th	Day	30% 14% 26% 18% 10% 1	374
	21st to end	Day	34% 14% 29% 17% 6%	396
November	1st to 10th	Day	30% 15% 24% 22% 8% 1	365
	11th to 20th	Day	28% 16% 29% 17% 9%	370
	21st to end	Day	32% 18% 30% 17% 3 1	181
December	1st to 10th	Day	33% 12% 27% 19% 6% 3	180
	11th to 20th	Day	31% 18% 29% 17% 3 2	180
	21st to end	Day	34% 17% 32% 13% 4 1	198
January	1st to 10th	Night	26% 16% 32% 22% 4	760
	11th to 20th	Night	25% 15% 30% 25% 4	760
	21st to end	Night	17% 12% 34% 30% 6% 1	836
February	1st to 10th	Night	19% 12% 34% 28% 6%	760
	11th to 20th	Night	21% 15% 39% 20% 4 1	743
	21st to end	Night	24% 12% 33% 27% 4	628
March	1st to 10th	Night	23% 11% 35% 26% 6%	760
	11th to 20th	Night	25% 14% 32% 22% 7% 1	760
	21st to end	Night	23% 10% 30% 29% 7% 1	821
April	1st to 10th	Night	29% 13% 26% 26% 6%	720
	11th to 20th	Night	25% 9% 34% 25% 6%	628
	21st to end	Night	29% 11% 29% 24% 6%	540
May	1st to 10th	Night	25% 10% 31% 28% 6%	501
	11th to 20th	Night	25% 9% 28% 31% 6%	354
	21st to end	Night	28% 5% 31% 28% 8%	389
June	1st to 10th	Night	25% 7% 27% 36% 5%	360
	11th to 20th	Night	19% 6% 26% 37% 12%	360
	21st to end	Night	23% 6% 24% 37% 10%	360
July	1st to 10th	Night	18% 5% 30% 37% 10% 1	350
	11th to 20th	Night	19% 3 22% 41% 14% 1	348
	21st to end	Night	16% 5% 18% 46% 14%	394
August	1st to 10th	Night	19% 4 13% 48% 16% 1	358
	11th to 20th	Night	16% 5% 21% 40% 16% 2	523
	21st to end	Night	19% 5% 25% 32% 18% 2	702
September	1st to 10th	Night	20% 5% 25% 34% 15% 1	720
	11th to 20th	Night	21% 7% 24% 31% 17% 2	720
	21st to end	Night	22% 7% 25% 30% 15% 1	720
October	1st to 10th	Night	22% 9% 26% 33% 8% 1	720
	11th to 20th	Night	29% 10% 24% 27% 9% 1	720
	21st to end	Night	30% 11% 30% 24% 4	792
November	1st to 10th	Night	26% 13% 26% 26% 9%	740
	11th to 20th	Night	26% 14% 27% 25% 8% 1	760
	21st to end	Night	30% 12% 31% 20% 7%	829
December	1st to 10th	Night	31% 12% 28% 22% 8% 1	850
	11th to 20th	Night	25% 18% 28% 22% 6% 1	850
	21st to end	Night	33% 16% 29% 18% 4 1	902

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