Saint-Hyacinthe
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Hyacinthe clear sky chart from 2005-11-06 to 2024-01-27.

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	19% 9% 4 6% 6% 3 5% 5% 5% 7% 33%	74876
	Night	20% 11% 4 7% 6% 3 4 4 4 6% 31%	75166
Transparency	Day	51% 8% 12% 19% 9% 1	74581
	Night	54% 6% 11% 18% 9% 1	74995
Seeing	Day	23% 13% 28% 23% 10% 3	13526
	Night	24% 10% 28% 27% 9% 1	22600

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	23% 17% 5% 11% 7% 4 4 3 3 4 20%	1517
	11th to 20th	Day	20% 17% 7% 8% 6% 3 3 4 4 4 23%	1520
	21st to end	Day	13% 13% 5% 9% 6% 4 6% 5% 5% 5% 27%	1632
February	1st to 10th	Day	18% 16% 6% 10% 6% 4 6% 3 5% 4 24%	1539
	11th to 20th	Day	15% 15% 6% 10% 6% 3 5% 4 4 6% 26%	1699
	21st to end	Day	19% 14% 5% 8% 6% 4 4 4 5% 5% 26%	1480
March	1st to 10th	Day	16% 12% 4 7% 7% 5% 5% 5% 4 6% 29%	1797
	11th to 20th	Day	18% 10% 5% 6% 6% 3 4 4 4 6% 33%	1846
	21st to end	Day	19% 11% 3 6% 6% 2 5% 5% 4 5% 34%	2376
April	1st to 10th	Day	23% 10% 4 7% 6% 3 4 4 4 6% 29%	2160
	11th to 20th	Day	22% 7% 3 5% 5% 3 3 5% 4 6% 38%	2134
	21st to end	Day	24% 9% 3 7% 5% 2 4 5% 4 6% 31%	2340
May	1st to 10th	Day	21% 7% 4 6% 6% 3 4 4 5% 6% 35%	2440
	11th to 20th	Day	18% 5% 3 5% 6% 3 5% 5% 6% 7% 37%	2478
	21st to end	Day	18% 6% 3 6% 5% 3 5% 5% 6% 8% 35%	2725
June	1st to 10th	Day	23% 7% 3 6% 5% 3 5% 5% 5% 8% 30%	2520
	11th to 20th	Day	17% 6% 2 5% 5% 3 5% 5% 5% 7% 40%	2520
	21st to end	Day	21% 7% 3 6% 5% 4 4 4 6% 8% 30%	2520
July	1st to 10th	Day	13% 6% 2 6% 5% 3 5% 4 6% 10% 40%	2520
	11th to 20th	Day	13% 5% 3 6% 6% 4 5% 6% 7% 10% 37%	2520
	21st to end	Day	14% 6% 3 6% 6% 3 5% 5% 6% 9% 37%	2744
August	1st to 10th	Day	13% 7% 3 6% 6% 4 5% 6% 7% 9% 35%	2506
	11th to 20th	Day	12% 5% 2 5% 6% 3 5% 5% 7% 9% 40%	2298
	21st to end	Day	15% 6% 2 5% 4 3 5% 5% 5% 7% 42%	2376
September	1st to 10th	Day	12% 6% 3 5% 5% 3 5% 7% 6% 8% 41%	2160
	11th to 20th	Day	17% 6% 2 4 4 2 3 4 5% 7% 48%	2055
	21st to end	Day	19% 4 2 5% 5% 3 4 4 5% 7% 40%	1980
October	1st to 10th	Day	21% 7% 3 6% 5% 3 5% 5% 6% 7% 32%	1903
	11th to 20th	Day	21% 8% 2 7% 7% 4 5% 5% 6% 6% 28%	1727
	21st to end	Day	27% 10% 4 5% 6% 3 4 4 4 5% 28%	1782
November	1st to 10th	Day	18% 10% 3 6% 6% 3 5% 5% 5% 7% 33%	1671
	11th to 20th	Day	19% 11% 5% 7% 6% 4 4 5% 4 7% 28%	1673
	21st to end	Day	23% 13% 4 7% 5% 3 5% 4 4 6% 25%	1520
December	1st to 10th	Day	25% 15% 5% 10% 7% 4 4 4 4 5% 18%	1520
	11th to 20th	Day	24% 14% 5% 7% 5% 2 4 4 4 5% 26%	1906
	21st to end	Day	28% 16% 6% 8% 5% 3 4 2 4 4 19%	2772
January	1st to 10th	Night	21% 17% 6% 10% 7% 3 4 4 4 4 20%	2649
	11th to 20th	Night	18% 16% 6% 10% 7% 4 4 4 3 4 22%	2660
	21st to end	Night	16% 13% 6% 9% 8% 4 5% 4 4 5% 26%	2868
February	1st to 10th	Night	16% 16% 6% 11% 8% 4 5% 4 4 6% 21%	2419
	11th to 20th	Night	16% 13% 6% 9% 7% 5% 5% 4 4 4 28%	2147
	21st to end	Night	17% 14% 6% 7% 6% 3 4 4 5% 4 30%	1776
March	1st to 10th	Night	18% 14% 5% 9% 6% 3 4 4 4 4 29%	2150
	11th to 20th	Night	21% 12% 5% 6% 7% 4 3 4 4 5% 30%	2111
	21st to end	Night	18% 13% 4 7% 5% 3 4 4 4 4 35%	1980
April	1st to 10th	Night	25% 9% 4 7% 5% 3 4 4 4 5% 29%	1800
	11th to 20th	Night	23% 8% 3 5% 5% 3 4 4 5% 6% 34%	1774
	21st to end	Night	23% 9% 3 6% 5% 3 3 4 4 5% 34%	1620
May	1st to 10th	Night	24% 8% 3 6% 5% 3 4 5% 4 7% 32%	1535
	11th to 20th	Night	21% 7% 2 6% 5% 3 5% 5% 5% 5% 37%	1415
	21st to end	Night	19% 6% 3 5% 5% 3 4 4 5% 7% 39%	1550
June	1st to 10th	Night	24% 7% 3 5% 4 3 4 5% 6% 7% 31%	1440
	11th to 20th	Night	18% 5% 2 6% 5% 2 5% 5% 6% 8% 37%	1440
	21st to end	Night	17% 7% 4 6% 6% 3 5% 5% 6% 8% 34%	1440
July	1st to 10th	Night	15% 4 3 5% 6% 4 5% 5% 7% 9% 38%	1440
	11th to 20th	Night	11% 5% 2 5% 6% 4 5% 5% 7% 9% 39%	1440
	21st to end	Night	13% 4 3 6% 6% 4 6% 6% 7% 8% 38%	1574
August	1st to 10th	Night	15% 6% 2 5% 4 4 5% 5% 7% 8% 39%	1432
	11th to 20th	Night	13% 5% 3 6% 6% 3 5% 6% 6% 7% 41%	1579
	21st to end	Night	14% 6% 2 6% 5% 3 4 5% 5% 8% 41%	1980
September	1st to 10th	Night	15% 5% 2 6% 5% 3 4 5% 5% 7% 43%	1800
	11th to 20th	Night	16% 5% 2 4 4 2 4 3 5% 7% 47%	1903
	21st to end	Night	18% 6% 3 5% 5% 3 3 4 4 8% 41%	1980
October	1st to 10th	Night	19% 6% 3 6% 4 3 3 5% 5% 6% 39%	2056
	11th to 20th	Night	23% 8% 3 7% 5% 4 4 4 4 5% 32%	2232
	21st to end	Night	26% 8% 4 7% 6% 3 4 4 3 5% 29%	2574
November	1st to 10th	Night	19% 12% 4 5% 5% 3 4 5% 5% 5% 32%	2407
	11th to 20th	Night	20% 12% 4 6% 6% 3 4 4 5% 5% 31%	2503
	21st to end	Night	24% 14% 4 8% 5% 3 4 3 4 4 28%	2660
December	1st to 10th	Night	24% 17% 6% 8% 7% 3 4 4 3 5% 19%	2660
	11th to 20th	Night	24% 15% 6% 8% 6% 3 3 4 3 4 24%	3288
	21st to end	Night	27% 17% 5% 8% 6% 3 3 3 3 4 22%	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	71% 6% 9% 11% 4	1518
	11th to 20th	Day	65% 8% 9% 11% 7%	1520
	21st to end	Day	57% 9% 11% 15% 7% 1	1632
February	1st to 10th	Day	64% 6% 9% 15% 5% 1	1539
	11th to 20th	Day	60% 6% 12% 14% 7% 1	1708
	21st to end	Day	60% 5% 11% 14% 8% 1	1480
March	1st to 10th	Day	58% 6% 10% 16% 8% 2	1800
	11th to 20th	Day	52% 6% 14% 14% 12% 2	1846
	21st to end	Day	51% 6% 11% 19% 11% 2	2376
April	1st to 10th	Day	58% 5% 9% 17% 9% 2	2160
	11th to 20th	Day	48% 6% 9% 22% 13% 1	2134
	21st to end	Day	55% 6% 10% 17% 10% 3	2340
May	1st to 10th	Day	50% 6% 9% 20% 13% 2	2440
	11th to 20th	Day	46% 6% 12% 19% 14% 2	2482
	21st to end	Day	47% 8% 12% 18% 13% 2	2725
June	1st to 10th	Day	51% 8% 11% 19% 9% 1	2520
	11th to 20th	Day	43% 7% 12% 23% 13% 2	2520
	21st to end	Day	51% 8% 12% 19% 9%	2520
July	1st to 10th	Day	39% 10% 14% 26% 10%	2450
	11th to 20th	Day	41% 10% 16% 26% 8%	2445
	21st to end	Day	42% 9% 16% 24% 8%	2591
August	1st to 10th	Day	44% 10% 16% 24% 6%	2492
	11th to 20th	Day	39% 10% 18% 24% 10%	2298
	21st to end	Day	40% 8% 15% 25% 11%	2376
September	1st to 10th	Day	38% 10% 15% 26% 11% 1	2160
	11th to 20th	Day	37% 7% 13% 31% 13%	2055
	21st to end	Day	43% 8% 14% 25% 10%	1980
October	1st to 10th	Day	50% 8% 13% 20% 8%	1903
	11th to 20th	Day	53% 10% 14% 18% 5%	1727
	21st to end	Day	58% 7% 12% 16% 7% 1	1782
November	1st to 10th	Day	51% 8% 13% 20% 8% 1	1671
	11th to 20th	Day	55% 8% 13% 15% 9%	1673
	21st to end	Day	60% 9% 12% 14% 5%	1520
December	1st to 10th	Day	70% 7% 10% 10% 3	1520
	11th to 20th	Day	62% 6% 10% 16% 6%	1906
	21st to end	Day	69% 6% 11% 8% 5%	2772
January	1st to 10th	Night	68% 8% 8% 12% 4	2649
	11th to 20th	Night	66% 7% 9% 11% 6% 1	2660
	21st to end	Night	60% 6% 9% 14% 10% 1	2868
February	1st to 10th	Night	66% 5% 9% 14% 6% 1	2419
	11th to 20th	Night	60% 6% 9% 16% 8%	2149
	21st to end	Night	58% 6% 9% 15% 11% 1	1776
March	1st to 10th	Night	59% 4 9% 17% 9% 1	2160
	11th to 20th	Night	57% 5% 10% 14% 12% 2	2112
	21st to end	Night	53% 4 7% 19% 13% 3	1980
April	1st to 10th	Night	57% 5% 8% 17% 12% 1	1800
	11th to 20th	Night	51% 5% 8% 20% 14% 2	1774
	21st to end	Night	52% 5% 9% 18% 13% 3	1620
May	1st to 10th	Night	52% 5% 7% 18% 14% 4	1535
	11th to 20th	Night	48% 6% 10% 17% 16% 4	1416
	21st to end	Night	44% 7% 12% 20% 15% 3	1551
June	1st to 10th	Night	51% 7% 9% 22% 10% 1	1440
	11th to 20th	Night	45% 7% 10% 21% 13% 3	1440
	21st to end	Night	48% 9% 12% 19% 13%	1440
July	1st to 10th	Night	40% 9% 13% 24% 14% 1	1400
	11th to 20th	Night	38% 10% 14% 26% 12%	1392
	21st to end	Night	41% 9% 16% 25% 9% 1	1486
August	1st to 10th	Night	39% 10% 17% 24% 10%	1422
	11th to 20th	Night	40% 9% 17% 23% 10%	1579
	21st to end	Night	41% 7% 14% 26% 11% 1	1980
September	1st to 10th	Night	40% 8% 13% 24% 14% 1	1800
	11th to 20th	Night	36% 6% 14% 31% 11% 1	1903
	21st to end	Night	42% 7% 10% 26% 14% 1	1980
October	1st to 10th	Night	45% 7% 11% 23% 13% 1	2056
	11th to 20th	Night	54% 7% 11% 22% 6%	2232
	21st to end	Night	60% 6% 10% 15% 9% 1	2574
November	1st to 10th	Night	53% 6% 12% 21% 7% 1	2407
	11th to 20th	Night	55% 7% 12% 16% 9% 1	2503
	21st to end	Night	61% 6% 12% 16% 6%	2660
December	1st to 10th	Night	70% 5% 10% 11% 3	2660
	11th to 20th	Night	64% 5% 9% 15% 6%	3288
	21st to end	Night	68% 6% 9% 14% 4	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	29% 15% 30% 18% 7%	180
	11th to 20th	Day	27% 22% 31% 16% 4	180
	21st to end	Day	22% 19% 28% 23% 5% 2	188
February	1st to 10th	Day	35% 21% 27% 14% 2	204
	11th to 20th	Day	26% 17% 32% 21% 4	367
	21st to end	Day	25% 18% 30% 24% 3	346
March	1st to 10th	Day	24% 13% 32% 25% 5%	420
	11th to 20th	Day	22% 17% 34% 20% 6% 1	420
	21st to end	Day	27% 14% 27% 24% 7% 1	462
April	1st to 10th	Day	30% 11% 30% 20% 7% 2	420
	11th to 20th	Day	30% 18% 23% 18% 8% 3	412
	21st to end	Day	29% 15% 30% 15% 8% 3	420
May	1st to 10th	Day	25% 13% 31% 19% 10% 2	423
	11th to 20th	Day	19% 13% 29% 26% 11% 2	447
	21st to end	Day	18% 14% 35% 21% 9% 2	485
June	1st to 10th	Day	26% 12% 28% 25% 6% 2	450
	11th to 20th	Day	18% 10% 28% 30% 13% 1	450
	21st to end	Day	22% 9% 30% 23% 13% 3	450
July	1st to 10th	Day	14% 7% 27% 29% 20% 2	445
	11th to 20th	Day	14% 8% 29% 34% 12% 3	444
	21st to end	Day	17% 8% 26% 33% 14% 2	488
August	1st to 10th	Day	15% 7% 26% 30% 16% 5%	446
	11th to 20th	Day	13% 6% 23% 33% 18% 6%	439
	21st to end	Day	16% 12% 24% 24% 15% 10%	495
September	1st to 10th	Day	13% 9% 31% 28% 13% 6%	450
	11th to 20th	Day	17% 8% 24% 27% 15% 9%	450
	21st to end	Day	18% 10% 26% 23% 18% 5%	450
October	1st to 10th	Day	22% 12% 29% 20% 13% 4	450
	11th to 20th	Day	25% 14% 27% 20% 12% 2	413
	21st to end	Day	34% 11% 28% 20% 7%	396
November	1st to 10th	Day	26% 16% 29% 21% 7%	365
	11th to 20th	Day	27% 20% 26% 17% 8% 1	333
	21st to end	Day	29% 18% 31% 16% 6% 1	180
December	1st to 10th	Day	33% 13% 23% 22% 4 3	180
	11th to 20th	Day	27% 23% 32% 14% 3 1	180
	21st to end	Day	32% 21% 27% 16% 4 1	198
January	1st to 10th	Night	30% 12% 30% 23% 6%	760
	11th to 20th	Night	27% 14% 31% 21% 7%	760
	21st to end	Night	23% 11% 31% 28% 7%	820
February	1st to 10th	Night	26% 12% 34% 24% 4	720
	11th to 20th	Night	21% 15% 34% 25% 5% 1	703
	21st to end	Night	24% 13% 30% 29% 4	592
March	1st to 10th	Night	24% 12% 29% 30% 5%	720
	11th to 20th	Night	27% 12% 29% 24% 7%	720
	21st to end	Night	24% 11% 28% 28% 8% 1	792
April	1st to 10th	Night	29% 12% 26% 27% 6%	720
	11th to 20th	Night	27% 12% 28% 26% 7%	710
	21st to end	Night	29% 11% 29% 24% 7% 1	540
May	1st to 10th	Night	27% 9% 32% 24% 8% 1	455
	11th to 20th	Night	24% 8% 28% 30% 9% 1	354
	21st to end	Night	21% 8% 31% 33% 8%	389
June	1st to 10th	Night	28% 6% 28% 30% 8% 1	360
	11th to 20th	Night	20% 6% 29% 33% 13%	360
	21st to end	Night	16% 7% 28% 37% 12% 1	360
July	1st to 10th	Night	14% 6% 27% 39% 13% 1	350
	11th to 20th	Night	12% 3 25% 44% 16% 1	348
	21st to end	Night	12% 6% 24% 43% 14% 1	394
August	1st to 10th	Night	17% 5% 17% 39% 21% 1	358
	11th to 20th	Night	14% 4 21% 36% 23% 2	515
	21st to end	Night	17% 5% 23% 34% 18% 2	792
September	1st to 10th	Night	16% 6% 26% 35% 16% 1	720
	11th to 20th	Night	18% 7% 21% 33% 19% 3	720
	21st to end	Night	21% 8% 26% 29% 15% 2	720
October	1st to 10th	Night	20% 10% 29% 28% 12% 1	720
	11th to 20th	Night	27% 10% 26% 27% 9% 1	720
	21st to end	Night	30% 12% 29% 24% 5%	792
November	1st to 10th	Night	27% 13% 31% 22% 6% 1	740
	11th to 20th	Night	25% 15% 30% 20% 8% 1	760
	21st to end	Night	30% 15% 26% 22% 6% 1	760
December	1st to 10th	Night	34% 14% 24% 21% 6%	760
	11th to 20th	Night	29% 14% 29% 20% 6% 1	760
	21st to end	Night	35% 13% 26% 20% 5%	836

Page generated at 2024-01-24 09:37:28. Version ac07

Copyright 2024 Attilla Danko