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 2025-02-06.

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% 29%	111837
	Night	31% 11% 3 7% 4 3 3 3 4 5% 26%	115076
Transparency	Day	56% 7% 13% 16% 7% 1	111579
	Night	61% 6% 11% 15% 7% 1	114981
Seeing	Day	29% 8% 19% 23% 16% 5%	16172
	Night	36% 6% 14% 20% 17% 6%	24214

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% 13% 4 8% 3 3 3 2 4 4 12%	3179
	11th to 20th	Day	25% 11% 4 8% 4 4 3 3 4 6% 30%	3159
	21st to end	Day	42% 12% 3 6% 4 2 2 2 2 3 21%	3936
February	1st to 10th	Day	41% 10% 3 7% 3 5% 4 3 5% 4 15%	1721
	11th to 20th	Day	33% 12% 3 6% 3 3 3 3 4 5% 25%	1665
	21st to end	Day	32% 11% 2 6% 5% 4 3 3 5% 6% 22%	1451
March	1st to 10th	Day	29% 11% 3 8% 6% 5% 4 3 5% 5% 20%	3249
	11th to 20th	Day	30% 12% 4 9% 4 3 3 3 3 4 24%	3490
	21st to end	Day	28% 11% 4 9% 4 4 5% 3 5% 6% 22%	3825
April	1st to 10th	Day	32% 12% 3 8% 5% 4 4 3 4 5% 20%	2300
	11th to 20th	Day	28% 12% 2 6% 4 3 3 3 4 6% 27%	2438
	21st to end	Day	31% 10% 2 7% 4 4 4 3 5% 6% 26%	2470
May	1st to 10th	Day	22% 8% 3 6% 5% 4 4 3 4 5% 38%	4260
	11th to 20th	Day	16% 8% 3 8% 5% 5% 4 3 6% 8% 33%	4505
	21st to end	Day	24% 12% 3 8% 4 4 4 4 5% 6% 26%	5161
June	1st to 10th	Day	28% 10% 3 7% 4 3 5% 4 5% 6% 26%	2850
	11th to 20th	Day	20% 10% 3 8% 4 5% 4 4 6% 6% 28%	2850
	21st to end	Day	25% 9% 3 7% 4 4 4 3 5% 6% 30%	2850
July	1st to 10th	Day	11% 6% 2 4 4 3 3 3 4 5% 56%	4740
	11th to 20th	Day	8% 7% 2 6% 4 4 5% 5% 5% 6% 48%	4740
	21st to end	Day	17% 7% 2 6% 3 4 4 3 5% 7% 42%	5095
August	1st to 10th	Day	8% 7% 3 9% 6% 5% 5% 4 6% 9% 39%	4169
	11th to 20th	Day	17% 12% 5% 8% 5% 5% 5% 3 5% 6% 29%	4026
	21st to end	Day	18% 7% 3 6% 4 3 4 2 5% 7% 42%	4521
September	1st to 10th	Day	18% 6% 2 6% 4 3 4 4 5% 8% 40%	2353
	11th to 20th	Day	23% 8% 2 6% 4 5% 5% 3 5% 6% 33%	2092
	21st to end	Day	26% 7% 2 7% 4 4 3 3 4 6% 34%	2090
October	1st to 10th	Day	32% 8% 2 7% 5% 4 4 4 5% 6% 23%	3225
	11th to 20th	Day	38% 8% 3 6% 5% 4 4 3 4 5% 21%	3161
	21st to end	Day	27% 13% 3 8% 5% 4 4 3 3 4 27%	3101
November	1st to 10th	Day	42% 10% 3 6% 4 3 3 3 4 5% 17%	1597
	11th to 20th	Day	40% 12% 3 6% 6% 3 3 2 4 3 18%	1600
	21st to end	Day	40% 9% 3 7% 4 3 3 3 5% 4 19%	1535
December	1st to 10th	Day	25% 14% 5% 10% 6% 5% 4 3 4 4 19%	2290
	11th to 20th	Day	49% 13% 3 8% 4 3 3 3 2 2 11%	2645
	21st to end	Day	49% 13% 3 8% 4 4 3 2 3 3 9%	3498
January	1st to 10th	Night	41% 16% 4 8% 4 4 3 2 2 3 12%	6766
	11th to 20th	Night	29% 9% 2 6% 4 3 3 3 4 6% 32%	6739
	21st to end	Night	45% 10% 2 5% 3 2 3 2 2 3 22%	7035
February	1st to 10th	Night	39% 12% 3 6% 5% 4 4 3 4 5% 17%	2568
	11th to 20th	Night	32% 12% 3 7% 4 3 3 2 4 4 27%	2402
	21st to end	Night	33% 12% 3 7% 4 3 4 3 4 4 22%	2001
March	1st to 10th	Night	29% 11% 3 8% 5% 3 4 3 5% 5% 23%	3619
	11th to 20th	Night	26% 13% 4 10% 5% 4 4 3 4 4 23%	3489
	21st to end	Night	32% 14% 4 7% 5% 3 3 2 3 4 22%	3828
April	1st to 10th	Night	32% 14% 3 6% 4 4 4 3 4 5% 23%	1877
	11th to 20th	Night	31% 11% 3 7% 5% 4 3 3 4 5% 25%	1691
	21st to end	Night	29% 11% 3 8% 5% 4 4 2 4 4 26%	1710
May	1st to 10th	Night	20% 7% 2 5% 4 3 4 4 5% 7% 40%	2704
	11th to 20th	Night	13% 7% 3 9% 5% 5% 4 4 5% 7% 37%	2374
	21st to end	Night	28% 10% 3 7% 3 4 3 3 4 5% 31%	2414
June	1st to 10th	Night	26% 10% 3 9% 4 5% 4 3 5% 6% 25%	1330
	11th to 20th	Night	22% 10% 4 8% 6% 3 3 4 5% 6% 29%	1330
	21st to end	Night	21% 10% 4 6% 3 6% 4 4 5% 6% 31%	1330
July	1st to 10th	Night	9% 6% 2 5% 4 3 3 3 4 5% 55%	2220
	11th to 20th	Night	8% 9% 3 5% 4 3 3 3 3 6% 52%	2220
	21st to end	Night	17% 9% 3 6% 3 5% 4 3 4 5% 41%	2444
August	1st to 10th	Night	7% 8% 2 7% 4 3 5% 4 5% 7% 49%	2771
	11th to 20th	Night	14% 10% 5% 9% 5% 4 5% 4 5% 6% 32%	2812
	21st to end	Night	15% 8% 2 5% 3 5% 4 3 4 5% 45%	3146
September	1st to 10th	Night	14% 8% 3 7% 4 3 5% 3 4 7% 43%	1826
	11th to 20th	Night	23% 11% 3 5% 3 2 3 3 3 5% 38%	2085
	21st to end	Night	28% 7% 2 5% 3 3 3 3 4 6% 37%	2090
October	1st to 10th	Night	36% 7% 3 6% 4 3 3 3 4 4 27%	3754
	11th to 20th	Night	40% 7% 3 6% 4 4 4 3 4 5% 20%	3777
	21st to end	Night	31% 9% 3 8% 4 3 4 3 4 5% 25%	4455
November	1st to 10th	Night	41% 11% 3 7% 4 5% 4 3 4 4 16%	2699
	11th to 20th	Night	37% 13% 4 9% 6% 3 3 2 2 3 18%	2800
	21st to end	Night	42% 8% 3 6% 4 3 3 3 3 3 21%	2862
December	1st to 10th	Night	32% 12% 4 8% 5% 4 4 2 4 4 22%	4890
	11th to 20th	Night	45% 15% 4 8% 4 3 3 2 3 3 10%	5560
	21st to end	Night	47% 14% 3 7% 4 3 3 2 3 3 10%	7458

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	76% 4 5% 10% 3 1	3179
	11th to 20th	Day	56% 4 13% 19% 7% 1	3180
	21st to end	Day	71% 4 11% 11% 4	3936
February	1st to 10th	Day	71% 7% 7% 8% 5% 2	1721
	11th to 20th	Day	64% 5% 10% 11% 9% 1	1674
	21st to end	Day	62% 7% 10% 11% 7% 3	1451
March	1st to 10th	Day	63% 8% 10% 12% 7% 1	3249
	11th to 20th	Day	63% 6% 10% 13% 7% 1	3490
	21st to end	Day	61% 11% 16% 10% 2	3825
April	1st to 10th	Day	66% 7% 11% 9% 6% 1	2300
	11th to 20th	Day	60% 7% 9% 15% 8% 1	2438
	21st to end	Day	61% 8% 10% 15% 6% 1	2470
May	1st to 10th	Day	48% 8% 14% 23% 6%	4260
	11th to 20th	Day	45% 12% 18% 20% 5%	4508
	21st to end	Day	57% 11% 13% 12% 6% 1	5162
June	1st to 10th	Day	57% 10% 14% 13% 5% 1	2850
	11th to 20th	Day	54% 12% 13% 16% 5%	2850
	21st to end	Day	54% 9% 14% 16% 6% 1	2850
July	1st to 10th	Day	30% 7% 9% 27% 17% 10%	4666
	11th to 20th	Day	32% 7% 16% 32% 12%	4659
	21st to end	Day	40% 7% 21% 23% 8% 1	4934
August	1st to 10th	Day	38% 7% 17% 30% 8% 1	4152
	11th to 20th	Day	54% 8% 18% 12% 6% 2	4065
	21st to end	Day	41% 7% 22% 23% 7%	4520
September	1st to 10th	Day	41% 10% 14% 22% 9% 3	2353
	11th to 20th	Day	51% 9% 14% 15% 11% 1	2092
	21st to end	Day	50% 8% 14% 17% 8% 3	2090
October	1st to 10th	Day	59% 7% 14% 14% 5% 1	3225
	11th to 20th	Day	67% 5% 9% 14% 5%	3161
	21st to end	Day	62% 5% 9% 16% 7% 1	3101
November	1st to 10th	Day	71% 7% 8% 7% 6% 1	1597
	11th to 20th	Day	71% 5% 7% 9% 7% 1	1600
	21st to end	Day	68% 6% 8% 10% 6% 2	1535
December	1st to 10th	Day	67% 6% 9% 12% 4 1	2290
	11th to 20th	Day	81% 4 7% 4 3 1	2648
	21st to end	Day	82% 4 5% 5% 2 1	3498
January	1st to 10th	Night	78% 4 5% 9% 3 1	6766
	11th to 20th	Night	54% 3 13% 19% 9% 1	6780
	21st to end	Night	70% 3 7% 13% 6% 1	7035
February	1st to 10th	Night	70% 6% 7% 9% 7% 2	2568
	11th to 20th	Night	62% 5% 10% 12% 9% 2	2404
	21st to end	Night	65% 4 12% 11% 6% 2	2001
March	1st to 10th	Night	61% 8% 10% 13% 8% 2	3619
	11th to 20th	Night	63% 6% 8% 14% 8% 1	3490
	21st to end	Night	64% 7% 13% 12% 4	3828
April	1st to 10th	Night	64% 7% 10% 13% 6% 1	1877
	11th to 20th	Night	62% 6% 8% 14% 8% 2	1691
	21st to end	Night	62% 5% 9% 15% 8% 1	1710
May	1st to 10th	Night	41% 7% 19% 25% 7%	2704
	11th to 20th	Night	39% 13% 19% 23% 5% 1	2374
	21st to end	Night	54% 8% 12% 17% 5% 3	2414
June	1st to 10th	Night	58% 7% 15% 13% 4 2	1330
	11th to 20th	Night	53% 9% 14% 18% 4	1330
	21st to end	Night	52% 8% 17% 14% 7% 1	1330
July	1st to 10th	Night	30% 7% 9% 20% 22% 11%	2185
	11th to 20th	Night	31% 8% 13% 36% 11% 1	2178
	21st to end	Night	41% 9% 19% 24% 6% 1	2367
August	1st to 10th	Night	32% 9% 12% 35% 11% 1	2763
	11th to 20th	Night	52% 5% 20% 13% 7% 2	2839
	21st to end	Night	39% 7% 20% 26% 7%	3146
September	1st to 10th	Night	39% 9% 14% 24% 11% 2	1826
	11th to 20th	Night	49% 6% 11% 17% 15% 1	2085
	21st to end	Night	50% 6% 13% 19% 9% 2	2090
October	1st to 10th	Night	61% 4 14% 13% 7% 1	3754
	11th to 20th	Night	68% 4 9% 15% 4	3777
	21st to end	Night	61% 5% 12% 14% 7% 1	4455
November	1st to 10th	Night	72% 6% 8% 9% 4 1	2699
	11th to 20th	Night	74% 4 7% 8% 6% 1	2800
	21st to end	Night	67% 5% 9% 11% 5% 2	2862
December	1st to 10th	Night	67% 4 10% 13% 4 1	4890
	11th to 20th	Night	81% 4 5% 6% 3 1	5556
	21st to end	Night	80% 5% 6% 5% 2 1	7458

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% 13% 14% 16% 7% 2	200
	11th to 20th	Day	47% 10% 13% 23% 6% 3	200
	21st to end	Day	43% 10% 13% 18% 13% 4	411
February	1st to 10th	Day	45% 8% 20% 19% 7% 2	386
	11th to 20th	Day	39% 10% 20% 17% 12% 2	365
	21st to end	Day	38% 10% 24% 17% 8% 2	307
March	1st to 10th	Day	37% 9% 21% 17% 13% 3	404
	11th to 20th	Day	36% 12% 19% 20% 10% 3	460
	21st to end	Day	40% 6% 23% 19% 9% 3	506
April	1st to 10th	Day	37% 13% 24% 17% 7% 2	460
	11th to 20th	Day	31% 10% 20% 21% 14% 4	452
	21st to end	Day	35% 13% 23% 16% 9% 3	460
May	1st to 10th	Day	26% 9% 20% 26% 17% 3	463
	11th to 20th	Day	23% 6% 23% 25% 18% 4	562
	21st to end	Day	19% 10% 26% 27% 14% 3	735
June	1st to 10th	Day	32% 8% 20% 26% 13% 2	680
	11th to 20th	Day	21% 11% 24% 25% 17% 2	680
	21st to end	Day	23% 5% 20% 24% 25% 4	680
July	1st to 10th	Day	19% 4 19% 30% 24% 4	671
	11th to 20th	Day	13% 4 19% 34% 24% 7%	668
	21st to end	Day	12% 3 16% 31% 29% 8%	739
August	1st to 10th	Day	16% 4 15% 23% 32% 11%	539
	11th to 20th	Day	14% 4 15% 28% 30% 9%	477
	21st to end	Day	20% 6% 20% 26% 19% 9%	539
September	1st to 10th	Day	23% 5% 15% 26% 22% 8%	490
	11th to 20th	Day	31% 5% 16% 19% 20% 10%	490
	21st to end	Day	29% 8% 17% 24% 17% 5%	490
October	1st to 10th	Day	30% 7% 18% 22% 17% 7%	490
	11th to 20th	Day	38% 9% 19% 17% 10% 6%	490
	21st to end	Day	37% 12% 17% 19% 10% 5%	429
November	1st to 10th	Day	42% 9% 17% 18% 11% 2	229
	11th to 20th	Day	42% 12% 18% 9% 12% 9%	200
	21st to end	Day	47% 10% 17% 11% 10% 7%	200
December	1st to 10th	Day	38% 12% 16% 19% 9% 7%	200
	11th to 20th	Day	44% 8% 21% 15% 10% 3	200
	21st to end	Day	51% 11% 15% 16% 6% 1	220
January	1st to 10th	Night	53% 10% 16% 13% 6% 3	900
	11th to 20th	Night	47% 8% 13% 18% 12% 1	900
	21st to end	Night	47% 6% 13% 15% 14% 4	990
February	1st to 10th	Night	43% 8% 19% 21% 8% 1	795
	11th to 20th	Night	37% 7% 17% 25% 12% 1	744
	21st to end	Night	40% 10% 17% 23% 7% 3	628
March	1st to 10th	Night	38% 9% 17% 16% 16% 4	760
	11th to 20th	Night	40% 10% 16% 19% 13% 2	760
	21st to end	Night	43% 9% 13% 17% 13% 4	836
April	1st to 10th	Night	38% 9% 14% 21% 14% 4	670
	11th to 20th	Night	38% 5% 16% 25% 13% 3	563
	21st to end	Night	34% 8% 15% 25% 15% 3	570
May	1st to 10th	Night	27% 3 14% 27% 23% 7%	479
	11th to 20th	Night	22% 4 16% 24% 27% 7%	374
	21st to end	Night	25% 4 15% 25% 26% 6%	411
June	1st to 10th	Night	30% 5% 10% 26% 25% 5%	380
	11th to 20th	Night	23% 5% 18% 25% 24% 4	380
	21st to end	Night	23% 3 12% 26% 28% 8%	380
July	1st to 10th	Night	21% 2 12% 21% 31% 13%	370
	11th to 20th	Night	14% 2 10% 23% 39% 11%	368
	21st to end	Night	13% 1 9% 24% 34% 19%	434
August	1st to 10th	Night	16% 2 6% 19% 33% 24%	567
	11th to 20th	Night	14% 2 8% 20% 39% 17%	564
	21st to end	Night	23% 2 13% 23% 28% 11%	627
September	1st to 10th	Night	18% 2 10% 22% 33% 14%	686
	11th to 20th	Night	28% 5% 11% 18% 23% 15%	760
	21st to end	Night	33% 4 14% 22% 21% 6%	760
October	1st to 10th	Night	34% 3 14% 21% 21% 8%	760
	11th to 20th	Night	40% 5% 13% 18% 16% 8%	760
	21st to end	Night	41% 9% 16% 21% 11% 3	836
November	1st to 10th	Night	48% 8% 19% 17% 8% 1	780
	11th to 20th	Night	45% 10% 17% 18% 6% 4	800
	21st to end	Night	46% 6% 16% 17% 10% 5%	832
December	1st to 10th	Night	38% 8% 16% 19% 15% 3	900
	11th to 20th	Night	47% 8% 15% 19% 9% 1	900
	21st to end	Night	51% 9% 17% 18% 5% 1	990

Page generated at 2025-02-03 00:05:56. Version ac07

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