Estevan Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Estevan Point clear sky chart from 2005-11-06 to 2026-06-01.

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	26% 10% 3 7% 4 4 4 3 4 6% 28%	135806
	Night	31% 11% 3 7% 4 3 3 3 4 5% 26%	136076
Transparency	Day	56% 7% 13% 16% 7% 1	135504
	Night	61% 5% 11% 14% 7% 1	135957
Seeing	Day	29% 8% 19% 23% 16% 5%	17939
	Night	36% 7% 14% 20% 17% 6%	25880

By Month

Percentage Cloud Cover NW (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	43% 15% 4 8% 4 3 3 2 3 4 10%	4125
	11th to 20th	Day	27% 9% 3 6% 3 3 3 3 4 6% 33%	4119
	21st to end	Day	42% 12% 4 6% 4 2 2 2 3 3 21%	5103
February	1st to 10th	Day	40% 10% 3 7% 4 5% 4 2 5% 4 16%	1854
	11th to 20th	Day	33% 11% 3 6% 3 3 4 3 4 4 25%	1845
	21st to end	Day	33% 12% 2 6% 5% 4 3 3 5% 6% 21%	1599
March	1st to 10th	Day	34% 12% 3 8% 5% 4 4 3 4 5% 20%	4779
	11th to 20th	Day	29% 14% 5% 10% 5% 4 4 3 4 4 19%	5110
	21st to end	Day	33% 12% 4 9% 5% 4 4 3 4 5% 17%	5607
April	1st to 10th	Day	31% 12% 3 8% 5% 4 4 3 4 5% 22%	2543
	11th to 20th	Day	26% 12% 3 6% 4 3 3 3 4 6% 28%	2698
	21st to end	Day	29% 9% 2 7% 3 3 3 3 5% 6% 29%	2730
May	1st to 10th	Day	20% 9% 3 8% 5% 4 4 2 4 5% 36%	6230
	11th to 20th	Day	19% 8% 3 8% 5% 4 4 3 5% 8% 32%	6605
	21st to end	Day	26% 11% 3 8% 4 3 4 3 5% 7% 26%	7570
June	1st to 10th	Day	26% 10% 2 7% 4 3 5% 4 5% 6% 28%	3001
	11th to 20th	Day	20% 10% 3 8% 5% 5% 5% 4 6% 6% 28%	3000
	21st to end	Day	25% 9% 3 7% 4 4 4 3 5% 6% 30%	3000
July	1st to 10th	Day	11% 5% 2 5% 4 4 4 4 5% 7% 48%	6780
	11th to 20th	Day	6% 7% 2 6% 4 4 4 4 5% 6% 52%	6780
	21st to end	Day	13% 8% 3 9% 5% 5% 5% 5% 6% 8% 35%	7319
August	1st to 10th	Day	8% 7% 3 9% 6% 5% 5% 4 6% 9% 38%	4302
	11th to 20th	Day	17% 12% 5% 8% 5% 5% 5% 3 5% 6% 29%	4156
	21st to end	Day	17% 7% 3 6% 4 3 4 3 5% 7% 42%	4664
September	1st to 10th	Day	18% 8% 3 7% 4 3 4 4 4 8% 38%	2477
	11th to 20th	Day	24% 8% 3 6% 4 5% 5% 2 4 6% 34%	2202
	21st to end	Day	27% 8% 2 7% 4 4 3 3 4 6% 33%	2200
October	1st to 10th	Day	32% 8% 2 7% 5% 4 4 4 5% 6% 23%	3327
	11th to 20th	Day	37% 8% 3 6% 5% 4 3 3 4 5% 22%	3261
	21st to end	Day	27% 13% 3 8% 5% 4 4 3 3 4 26%	3200
November	1st to 10th	Day	41% 10% 3 6% 4 3 3 3 4 5% 17%	1678
	11th to 20th	Day	40% 12% 3 6% 5% 3 3 2 4 3 19%	1680
	21st to end	Day	39% 10% 3 8% 5% 3 3 3 5% 4 18%	1612
December	1st to 10th	Day	27% 14% 5% 10% 5% 5% 4 3 4 4 19%	2360
	11th to 20th	Day	49% 13% 3 8% 4 3 3 3 2 2 10%	2715
	21st to end	Day	48% 14% 3 8% 4 4 3 2 3 3 9%	3575
January	1st to 10th	Night	44% 16% 4 8% 4 3 3 2 2 3 11%	8770
	11th to 20th	Night	30% 7% 2 5% 3 2 3 3 4 6% 35%	8779
	21st to end	Night	42% 11% 3 6% 3 3 3 2 2 3 21%	9102
February	1st to 10th	Night	39% 12% 3 6% 5% 3 3 3 4 5% 18%	2764
	11th to 20th	Night	31% 12% 3 7% 4 3 3 3 4 4 27%	2662
	21st to end	Night	34% 12% 4 7% 4 3 4 3 4 4 21%	2205
March	1st to 10th	Night	33% 12% 3 8% 5% 3 4 3 4 4 22%	5323
	11th to 20th	Night	25% 15% 4 11% 5% 5% 4 2 4 4 20%	5109
	21st to end	Night	37% 14% 3 8% 5% 4 3 2 3 4 17%	5610
April	1st to 10th	Night	31% 13% 3 6% 4 4 4 3 4 5% 24%	2074
	11th to 20th	Night	29% 11% 3 7% 5% 4 4 3 4 5% 26%	1871
	21st to end	Night	27% 10% 3 7% 5% 4 4 2 5% 5% 28%	1890
May	1st to 10th	Night	17% 7% 2 6% 4 4 4 4 5% 7% 39%	3959
	11th to 20th	Night	19% 8% 3 8% 5% 5% 4 4 5% 7% 32%	3494
	21st to end	Night	33% 9% 3 6% 3 3 3 3 5% 5% 28%	3547
June	1st to 10th	Night	25% 9% 3 9% 4 5% 4 3 5% 6% 27%	1400
	11th to 20th	Night	22% 10% 4 8% 6% 3 3 4 5% 6% 30%	1400
	21st to end	Night	21% 11% 4 6% 3 6% 4 4 5% 6% 31%	1400
July	1st to 10th	Night	9% 8% 3 6% 5% 4 4 3 5% 6% 47%	3180
	11th to 20th	Night	6% 9% 4 5% 3 3 2 3 3 5% 58%	3180
	21st to end	Night	13% 10% 6% 9% 3 4 4 3 4 5% 40%	3512
August	1st to 10th	Night	7% 8% 2 7% 4 3 5% 4 5% 7% 49%	2858
	11th to 20th	Night	14% 10% 5% 9% 5% 4 5% 4 5% 6% 33%	2902
	21st to end	Night	15% 8% 2 5% 3 5% 4 3 4 5% 45%	3245
September	1st to 10th	Night	14% 9% 3 8% 4 3 4 3 4 7% 41%	1922
	11th to 20th	Night	23% 11% 3 5% 3 3 3 2 3 5% 38%	2195
	21st to end	Night	29% 7% 2 5% 3 3 3 2 4 6% 36%	2200
October	1st to 10th	Night	35% 7% 3 6% 4 3 3 3 4 5% 28%	3872
	11th to 20th	Night	40% 7% 3 6% 4 4 4 3 4 5% 20%	3897
	21st to end	Night	31% 9% 3 8% 4 3 4 3 4 5% 25%	4598
November	1st to 10th	Night	41% 11% 3 8% 4 5% 4 3 4 4 16%	2838
	11th to 20th	Night	38% 13% 4 9% 6% 3 3 2 2 3 18%	2940
	21st to end	Night	41% 8% 3 6% 3 3 3 3 3 3 21%	3005
December	1st to 10th	Night	33% 12% 4 8% 5% 4 4 2 4 4 21%	5040
	11th to 20th	Night	45% 15% 4 8% 4 3 3 2 3 3 10%	5710
	21st to end	Night	46% 14% 4 8% 4 3 3 2 3 3 10%	7623

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	79% 4 5% 8% 3 1	4125
	11th to 20th	Day	52% 3 10% 18% 14% 3	4140
	21st to end	Day	71% 3 9% 14% 3	5104
February	1st to 10th	Day	70% 7% 7% 9% 5% 3	1854
	11th to 20th	Day	64% 5% 9% 12% 10% 1	1854
	21st to end	Day	64% 7% 10% 10% 7% 3	1599
March	1st to 10th	Day	67% 6% 7% 13% 6% 1	4779
	11th to 20th	Day	68% 5% 7% 12% 8% 1	5110
	21st to end	Day	70% 8% 12% 8% 2	5607
April	1st to 10th	Day	65% 7% 11% 11% 5% 1	2543
	11th to 20th	Day	59% 6% 10% 15% 8% 1	2698
	21st to end	Day	57% 7% 11% 18% 6% 1	2730
May	1st to 10th	Day	52% 6% 11% 23% 8%	6230
	11th to 20th	Day	48% 9% 18% 21% 4	6608
	21st to end	Day	57% 8% 16% 11% 7% 1	7571
June	1st to 10th	Day	55% 10% 14% 13% 6% 1	3001
	11th to 20th	Day	54% 12% 14% 16% 4	3000
	21st to end	Day	54% 9% 14% 16% 6% 1	3000
July	1st to 10th	Day	35% 9% 16% 22% 12% 7%	6706
	11th to 20th	Day	30% 7% 18% 28% 17%	6699
	21st to end	Day	43% 7% 24% 20% 6%	7113
August	1st to 10th	Day	39% 7% 17% 29% 8% 1	4285
	11th to 20th	Day	54% 8% 17% 12% 7% 2	4195
	21st to end	Day	41% 7% 21% 22% 7%	4663
September	1st to 10th	Day	43% 10% 14% 21% 8% 3	2477
	11th to 20th	Day	50% 9% 14% 16% 11% 1	2202
	21st to end	Day	51% 8% 13% 17% 8% 2	2200
October	1st to 10th	Day	59% 7% 14% 14% 5% 1	3327
	11th to 20th	Day	66% 5% 9% 15% 6%	3261
	21st to end	Day	62% 5% 10% 16% 7% 1	3200
November	1st to 10th	Day	71% 6% 9% 7% 6% 1	1678
	11th to 20th	Day	71% 4 7% 9% 7% 1	1680
	21st to end	Day	69% 6% 8% 10% 5% 2	1612
December	1st to 10th	Day	68% 6% 9% 12% 4 1	2360
	11th to 20th	Day	81% 4 7% 4 3 1	2718
	21st to end	Day	82% 4 5% 5% 2 1	3575
January	1st to 10th	Night	80% 3 5% 8% 3 1	8770
	11th to 20th	Night	51% 3 10% 17% 15% 3	8820
	21st to end	Night	69% 3 7% 13% 7%	9102
February	1st to 10th	Night	69% 6% 6% 10% 7% 2	2764
	11th to 20th	Night	62% 5% 9% 13% 9% 2	2664
	21st to end	Night	66% 4 12% 10% 6% 1	2205
March	1st to 10th	Night	64% 6% 8% 12% 8% 2	5323
	11th to 20th	Night	65% 6% 7% 13% 8% 1	5110
	21st to end	Night	72% 5% 10% 10% 3	5610
April	1st to 10th	Night	62% 6% 10% 15% 6% 1	2074
	11th to 20th	Night	60% 6% 9% 15% 8% 2	1871
	21st to end	Night	59% 5% 10% 18% 7% 1	1890
May	1st to 10th	Night	43% 6% 16% 27% 9%	3956
	11th to 20th	Night	47% 9% 18% 21% 4	3494
	21st to end	Night	58% 7% 14% 16% 4 2	3547
June	1st to 10th	Night	56% 7% 16% 14% 6% 2	1400
	11th to 20th	Night	53% 9% 15% 19% 4	1400
	21st to end	Night	52% 8% 18% 14% 7% 1	1400
July	1st to 10th	Night	37% 10% 14% 16% 16% 8%	3145
	11th to 20th	Night	28% 6% 19% 31% 16% 1	3138
	21st to end	Night	43% 8% 25% 19% 4 1	3414
August	1st to 10th	Night	33% 9% 12% 35% 11% 1	2850
	11th to 20th	Night	52% 5% 19% 13% 7% 2	2929
	21st to end	Night	39% 7% 20% 26% 7%	3245
September	1st to 10th	Night	42% 9% 14% 23% 11% 2	1922
	11th to 20th	Night	49% 5% 12% 18% 14% 1	2195
	21st to end	Night	51% 6% 13% 18% 9% 2	2200
October	1st to 10th	Night	60% 4 14% 13% 7% 1	3872
	11th to 20th	Night	67% 4 9% 16% 4	3897
	21st to end	Night	61% 5% 12% 13% 7% 1	4598
November	1st to 10th	Night	72% 6% 8% 9% 4 1	2838
	11th to 20th	Night	74% 4 7% 8% 6% 1	2940
	21st to end	Night	67% 5% 9% 11% 5% 2	3005
December	1st to 10th	Night	68% 4 10% 12% 4 1	5040
	11th to 20th	Night	81% 4 5% 6% 3 1	5706
	21st to end	Night	80% 5% 6% 6% 2 1	7623

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	50% 12% 15% 15% 6% 2	220
	11th to 20th	Day	46% 9% 12% 21% 7% 5%	220
	21st to end	Day	43% 10% 12% 19% 12% 4	443
February	1st to 10th	Day	44% 8% 19% 19% 7% 2	430
	11th to 20th	Day	38% 9% 19% 17% 13% 2	425
	21st to end	Day	41% 10% 24% 16% 7% 1	355
March	1st to 10th	Day	39% 10% 20% 17% 12% 3	472
	11th to 20th	Day	39% 12% 19% 19% 9% 3	540
	21st to end	Day	42% 7% 22% 18% 9% 3	594
April	1st to 10th	Day	36% 12% 22% 18% 9% 3	540
	11th to 20th	Day	28% 9% 23% 21% 16% 4	532
	21st to end	Day	32% 11% 23% 19% 11% 4	540
May	1st to 10th	Day	24% 9% 20% 26% 18% 3	543
	11th to 20th	Day	23% 8% 23% 26% 17% 4	650
	21st to end	Day	19% 10% 27% 27% 14% 3	845
June	1st to 10th	Day	30% 9% 20% 26% 14% 2	731
	11th to 20th	Day	21% 10% 23% 27% 17% 2	730
	21st to end	Day	24% 6% 19% 24% 24% 3	730
July	1st to 10th	Day	19% 4 19% 31% 23% 4	721
	11th to 20th	Day	13% 5% 19% 34% 23% 7%	718
	21st to end	Day	12% 3 15% 31% 31% 9%	794
August	1st to 10th	Day	16% 4 14% 24% 32% 10%	582
	11th to 20th	Day	15% 4 15% 28% 29% 9%	517
	21st to end	Day	19% 6% 18% 25% 21% 11%	583
September	1st to 10th	Day	23% 6% 15% 26% 23% 8%	530
	11th to 20th	Day	32% 5% 15% 19% 20% 9%	530
	21st to end	Day	31% 7% 17% 25% 15% 5%	530
October	1st to 10th	Day	31% 6% 19% 21% 16% 7%	530
	11th to 20th	Day	38% 9% 20% 17% 11% 6%	530
	21st to end	Day	38% 11% 17% 19% 10% 5%	462
November	1st to 10th	Day	43% 8% 18% 18% 11% 2	250
	11th to 20th	Day	44% 12% 17% 9% 10% 8%	220
	21st to end	Day	46% 9% 18% 10% 10% 6%	220
December	1st to 10th	Day	42% 11% 15% 17% 8% 6%	220
	11th to 20th	Day	46% 9% 20% 14% 9% 3	220
	21st to end	Day	50% 11% 16% 15% 7% 1	242
January	1st to 10th	Night	54% 10% 15% 13% 6% 3	950
	11th to 20th	Night	46% 8% 13% 18% 13% 2	950
	21st to end	Night	47% 6% 13% 16% 14% 4	1045
February	1st to 10th	Night	44% 8% 18% 21% 8% 1	856
	11th to 20th	Night	37% 7% 16% 25% 14% 1	824
	21st to end	Night	42% 10% 17% 22% 6% 3	692
March	1st to 10th	Night	39% 10% 16% 17% 16% 4	840
	11th to 20th	Night	41% 10% 16% 18% 12% 2	840
	21st to end	Night	43% 9% 14% 18% 13% 3	924
April	1st to 10th	Night	37% 9% 14% 21% 15% 4	740
	11th to 20th	Night	36% 6% 17% 24% 15% 3	623
	21st to end	Night	32% 7% 15% 26% 17% 3	630
May	1st to 10th	Night	26% 3 13% 27% 24% 7%	529
	11th to 20th	Night	24% 5% 17% 23% 25% 7%	414
	21st to end	Night	26% 4 14% 27% 25% 5%	455
June	1st to 10th	Night	28% 5% 12% 26% 24% 5%	400
	11th to 20th	Night	23% 5% 17% 26% 24% 5%	400
	21st to end	Night	23% 3 11% 27% 28% 8%	400
July	1st to 10th	Night	21% 2 13% 22% 30% 12%	390
	11th to 20th	Night	13% 2 11% 24% 40% 10%	388
	21st to end	Night	13% 2 8% 23% 35% 19%	457
August	1st to 10th	Night	16% 3 7% 19% 33% 23%	597
	11th to 20th	Night	15% 3 8% 20% 37% 16%	594
	21st to end	Night	22% 2 12% 22% 28% 14%	660
September	1st to 10th	Night	18% 3 10% 23% 33% 14%	722
	11th to 20th	Night	28% 6% 11% 19% 23% 15%	800
	21st to end	Night	34% 4 15% 22% 20% 6%	800
October	1st to 10th	Night	33% 4 14% 21% 21% 8%	800
	11th to 20th	Night	39% 6% 14% 19% 16% 7%	800
	21st to end	Night	41% 9% 16% 20% 11% 3	880
November	1st to 10th	Night	47% 9% 19% 17% 8% 1	820
	11th to 20th	Night	45% 10% 17% 19% 6% 3	840
	21st to end	Night	45% 6% 16% 18% 10% 4	875
December	1st to 10th	Night	40% 8% 16% 18% 15% 3	950
	11th to 20th	Night	48% 8% 15% 18% 8% 1	950
	21st to end	Night	50% 9% 17% 18% 5%	1045

Page generated at 2026-05-28 22:53:30. Version ac07

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